W2008: Biology and Management of Iris yellow spot virus (IYSV), Other Diseases, and Thrips in Onions (from W1008)

(Multistate Research Project)

Status: Inactive/Terminating

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Date of Annual Report: 02/06/2013

Report Information

Annual Meeting Dates: 12/14/2012 - 12/14/2012
Period the Report Covers: 10/01/2011 - 09/01/2012

Participants

Clint Shock, Oregon State University, clinton.shock@oregonstate.edu;Howard Schwartz, Colorado State University, howard.schwartz@colostate.edu;Chris Cramer, New Mexico State University, cscramer@nmsu.edu;Beth Gugino, Pennsylvania State University, bkgugino@psu.edu;Michael Havey, USDA-ARS and Univ. of Wisconsin, mjhavey@wisc.edu;Cesar Saray, Olam, cesar.saray@olamnet.com;Tom Turini, UC Ag and Nat Res, taturini@ucanr.edu;Brenda K Schroeder, Washington State University, bschroeder@wsu.edu;Claudia Nischwitz, Utah State University, claudia.nischwitz@usu.edu;Patrice DuBois, Nunhems Bayer, patrice.dubois@bayer.com;Stuart Reitz, Oregon State University, stuart.rietz@oregonstate.edu;Thaddeus Gourd, Colorado State University, tgourd@adcogov.edu;Jianhua Mo, NSW Dept Primary Industry, Australia, jianhua.mo@dpi.nsw.gov.au;Ivan L Miller, Tanimura and Antle, imiller@3starlettuce.com;Sudeep Bag, Washington State University, sudeep.bag@email.wsu.edu;Steve McArthur, Vigour, New Zealand, steve@vigour.com.nz;Cynthia Feibert, Treasure Valley Community College, cfeibert@tvcc.cc;Erik Feibert, Oregon State University, erik.feibert@oregonstate.edu;Marion Paibomesai, Ontario Ministry of Agriculturre, marion.paibomesai@ontario.ca;Lowell L Black, Seminis Vegetable Seeds, lowell.black@monsanto.com;Ryon Ottoman, Bejo Seeds, r.ottoman@bejoseeds.com;Wayne Mininger, National Onion Association, wmininger@onions-usa.org;Bill Buhrig, University of Idaho-Parma, buhrigw@uidaho.edu;Rick Jones, Monsanto, rick.jones@monsanto.com;Robert Ehn, CA Garlic and Onion, robertehn@sbcglobal.net;Elise Felix, Technisem, elise.felix@technisem.com;Mike Bowman, Nunhems USA, mike.bowam@bayer.com;David Whitwood, Crookham Company, davew@crookham.com;Deron Beck, Monsanto, deron.g.beck@monsanto.com;Jason Cavatorta, Seminis/Monsanto, jason.cavatorta@monsanto.com;Bob Simerly, McCain Foods, bob.simerly@mccain.com;Carrie Wohleb, Washington State Univ, cwohleb@wsu.edu;Joel Canestrino, Hazera Seeds Inc, jcanestrino@hazerainc.com;Mary Ruth McDonald, University of Guelph, mrmcdona@uoguelph.ca;Al Burkett, EWSY LLC, albmcb@live.com;Lindsey du Toit, Washington State University, dutoit@wsu.edu;Tim Waters, Washington State University, twaters@wsu.edu;Lee Sommers, Colorado State University, lee.sommers@colostate.edu;Rene Emch, Nunhems, rene.emch@bayer.com;Dan Drost, Utah State University, dan.drost@usu.edu;Rick Watson, Nunhems, rick.watson@bayer.com;Bill Chounet, ProAg, wchounet@proag.biz;Christy Hoepting, Cornell Coop Ext Vegetable Program, cah59@cornell.edu;Mark Uchanski, NMSU, uchanski@nmsu.edu;Steve Beer, Cornell University, svb1@cornell.edu;Ray Muhyi, NMSU, rmuhyi@nmsu.edu;Juan Carlos Brevis, Enza Zaden USA, juan.brevis@enzausa.com;Dennis Atkinson, Seminis Vegetable Seeds, dennis.atkinson@monsanto.edu;Stephanie Walker, NMSU, swalker@nmsu.edu;Shannon Pike, Enza Zaden USA, shannon.pike@enzausa.com;

Brief Summary of Minutes

2012 Officers: Chair: Shannon Pike, Enza USA, California; Vice Chair: Brian Nault, Cornell University, New York (not present); Secretary: Joel Canestrino, Hazera Seeds Inc., California; Past Chair: Hanu Pappu, Washington State University, Washington (not present).

At 8:00am Shannon Pike called the meeting to order, distributed agendas and initiated the passing of a sign-in sheet for attendees.

Lee Sommers, Colorado State University, Administrative Advisor Update as liaison of the W2008.
-25% of all Hatch Funds have to be spent on Multi-state projects.
-REE Undersecretary and Chief Scientist is Cathy Woteki with responsibility for ARS, ERS, NAL, NASS and NIFA.
-Sonny Ramaswamy, former Dean of Oregon St. Univ. is currently Director of USDA NIFA
-The Farm Bill (FB) is still appending approval by the House; its approval is needed to fund all programs in 2013. The 2012 FB had mandatory spending for specialty crops, uncertain this will be carried over in FY2013 FB.
-NIMSS (National Information Management Support System) can be accessed for updates on proposals and projects.
-The minutes from the 2012 W2008 meeting and an Annual Report must be turned in within 60 days of the meeting in order for the 2013 meeting to be authorized.
-CARET (Council for Ag Res., Ext. and Teaching) is an advisory council to the Association of Public and Land-Grant Universities. Each state can appoint several Lay representatives to CARET.
-CE and AES have enlisted KGlobal for joint marketing and education of SAES and Extension programs. KGlobal has initiated the Twitter Feed-@AgIsAmerica to post updates, events and news items related to CE and AES. It has 30,000 followers and the target audience is legislators and other policymakers. A website is also in development.
Lee Sommers also announced he will be retiring in the middle of 2013.

Shannon Pike- Location for W2008 2013 meeting: Locations for the 2013 W2008 meeting were discussed. Shannon suggested Kona, HI to coincide with the NOA national meeting. Brian Nault concurred, in absentia, according to Shannon. Dan Drost, Utah, suggested Hawaii was too far and too expensive to justify for a half-day long meeting and advocated a central, continental-US location. Christy Hoepting, NY, concurred. Joel Canestrino, CA, suggested Dallas or Houston as possible locations for the meeting. Howard Schwartz, Colorado, offered to host meeting in Denver near or at the airport. A show of hands favored Denver as the location and it was agreed that the W2008 officers would coordinate with Howard Schwartz, Thad Gourd and Robert Sakata to organize the meeting. The meeting will be held on Thursday, December 12, 2013. Shannon reminded the participants that the W2008 Project has a Public Relations and Report Committee. He asked that an announcement be sent to OnionWorld Magazine that the W2008 meeting has concluded and provide links to Annual Report Summaries. Also, the date of the W2008 2013 meeting in Denver will be provided (20-30 days ahead of desired run date in OnionWorld).

NEW MEXICO. Chris Cramer, New Mexico State University, provided update
-IYSV evaluations in 2012 a bit better than 2011, good spread of virus in field.
-Cool temps in June and July and new field with no previous history of onion production led to low stress on plants.
-Poor stand establishment in seeded plots along with weak or limited seed of PI accessions meant all plots established via transplants.
-Made seed of some first-year bulb selections, which will be evaluated as 2nd -generation material in summer of 2013.
-Date tables with extensive evaluations for thrips numbers, leaf color and glossiness and IYSV disease ratings for lines derived from previous bulb selections were provided by Dr. Cramer and explained.
-No more funding for 2013 evaluations and Dr. Cramer would really like to continue evaluations. More seed of selected resistant bulbs will be made this year and CC will announce availability to seed companies at the end of 2013. Selected inbred bulbs were also crossed to a male sterile and that seed grown out in counting-blocks; it is known that some of the IYSV resistant lines will also be maintained.

COLORADO. Howard Schwartz, Colorado State University, provided update
-2012 weather not conducive to high IYSV pressure. Will re-test some entries.
-Researched survival and proliferation of thrips in and around cull piles
-Evaluated influence of Living Mulch, companion crop planted with onions, on thrips and IYSV damage.
-Demonstrated Vydate still effective at reducing thrips populations and evaluated new material, cyantraniliprole, which was also effective at reducing thrips populations.
-Evaluated several pesticide seed coatings on the cultivar Vaquero to see how they influenced thrips populations during the early season. The treatments included the following: 1)Thiram, 2) Coronet, Allegiance and Thiram, 3) Thiram, Coronet, Allegiance and Sepresto. Treatment number three was much more effective than treatment 1 (which does not contain an insecticide) at reducing thrips and IYSV incidence, delivering higher yields and more jumbo bulbs.
-In Xanthomonas leaf-blight trials, Kocide suppressed the disease as did Novozyme. The biological MBI 106 (Bacillus subtilis) not as effective, but better than the UTC.
-In Botrytis Storage Rot screening, Oxidate+Pristine reduced storage rot by 25% and MBI 106 reduced it by 20%.

WASHINGTON. Lindsey du Toit, Brenda Schroeder, Tim Waters, Washington State University, provided update
-Early season was cool and wet with substantial losses to hail.
-Aug to Oct was hot and dry. Late maturing varieties were delayed in maturing due to cool, wet early season. Storage rot was already starting to show up at some sheds.
-Very few reports of problems with IYSV this year.
-Thrips collected in WA still showing some resistance to pyrethroids.
-Cool weather early in season led to higher than normal bolting for some cultivars.
-Continued research on impact of curing temperature and duration on subsequent rot in storage. Growers heat treat at 95 degrees F to dry down necks and reduce loss to neck rot (fungus) even though this might increase problems with bacterial rots later. Bringing onions in with better necks, cured and dried in the field and then curing at ambient forced-air temps for a few days would reduce losses to bacteria in storage.

UTAH. Dan Drost and Claudia Nischwitz, Utah State University, provided update
-Studying neighboring crops and edge effects in onion fields as it pertains to distribution of thrips in the field and progression of IYSV through the field.
-Egg laying preferences of thrips not influenced much by germplasm.
-Thrips can proliferate on alfalfa plants, 120-140 per plant in July-Aug; they can reproduce on some weeds reaching 20-40 per plant; they do not proliferate on corn; on wheat they can reach 4-5 thrips per plant in June-July.
-Mallow, prickly lettuce, flixweed, clasping pepperwood, alfalfa, wheat all tested positive for IYSV and provided a Green Bridge for the virus.

OREGON. Clint Shock, Oregon State University, provided update
-Feb and March were dry with no weed emergence; onion trials were planted a bit earlier than normal; wet weather and weed pressure followed.
-August much warmer than normal, had prolonged dry, warm weather to field cure and harvest onions.
-Early harvest led to favorable pricing and some Fresh Market sales, easing demands on storage space.
-IYSV pressure was low in 2012; thrips not problematic, well controlled by growers.
-Some lots recently placed into storage seem to be storing rather poorly.
-Conducted plant population X irrigation method trials for yield and size distribution.
-Conducted variety trials of commercial hybrids.
-Alternative methods to control thrips were trialed (Surround, Mycotrol, Diatomaceous Earth); none were as good as growers standard control methods and all showed substantial thrips damage.

WISCONSIN. Mike Havey, University of Wisconsin, provided update
-IYSV not yet described as occurring in WI and they are not looking for it.
-Havey produces seed from IYSV-resistant selected bulbs acquired from Howard Schwartz in Colorado; many of the Spanish lines tend to bolt or flower poorly after cutting and planting.
-Seed of IYSV-resistant Long-Day germplasm will eventually be released by the Havey Lab.

PENNSYLVANIA. Beth Gugino, Pennsylvania State University, provided update
-Pennsylvania has 300-400 acres of onions, mostly as 0.25-2 acre fields grown by the Amish and Mennonite communities. It is all sweet onion production, grown on plastic, from transplants with the varieties Candy, Expression and Candor. Marketed through Co-ops, produce auctions and roadside stands via the PA Simply Sweet trademark and marketing order program.
-MO assessment leads to $5,000-6,000 available annually for research.
-Production suffers from onion collapse in the field and in storage from a complex of bacterial rots (center rot, sour skin, slippery skin).
-Investigation into mulches showed that bacterial rot is worst on standard black plastic. Bare soil has the lowest disease pressure, but not useful due to weed problems. Silver mulch and biodegradable black mulch were much better for reduced disease incidence and did not alter yields or size distribution.
-Checked sources of bacterial pathogens, seed, weeds, transplants, soil, crop residues and thrips. Growing cycle is only 90 days; many growers do not control thrips. P. agglomerans found on transplants from all areas; sour skin did not come in with transplants.
-Reducing plant spacing from 10 x 6 or 6 x 6, to 4 x 6 reduced bacterial rot problems.

NEW YORK. Christy Hoepting and Steve Beer, Cornell University, provided update
-Compared thrips control following a standard spray program for thrips (2x applications of Movento, 2x of Agri-Mek, 2x of Lannate, 2x of Radiant) with one based on scouting and spraying based on thrips/leaf action thresholds; many growers only needed 3-4 sprays for the whole season.
-Continue to evaluate Benevia prior to registration; control has been very good and is comparable to Radiant and Movento.
-Co-applications of Bravo (chlorothalonil) and either Movento or Agri-Mek greatly reduced efficacy of the insecticide. Other fungicides such as Scala, Quadris, Rovral and Dithane F45 Rainshield mixed with these insecticides did not interfere with thrips control.
-Combination of reduced N use and higher plant stands reduced the percent of bulbs affected by bacterial rots.
-Plots with excellent thrips control had significantly higher bacterial bulb decay problems. Thought is that aggressive adjuvants used with insecticides also strip waxy cuticle from onions and make them more susceptible to foliar disease. Leaf damage from aggressive herbicide programs might also expose leaves to more foliar disease.

Shannon Pike- Deliverables and 2014 W2008/NARC Meeting
-Minutes for W2008 meeting 2012 need to be submitted by Secretary and accepted by officers.
-All researchers involved with W2008 need to provide an annual summary report that includes: 1) how the 4 objectives of W2008 were met, 2) Impacts, and 3) List of Publications. These will be delivered to Brian Nault by Jan 20th for comments and editing between Jan 20th and Feb 1st. Minutes and Annual summary reports will be sent by Brian Nault to Lee Sommers on or about Feb 1 to satisfy requirements for funding of W2008 meeting in 2013.
-Request for volunteers for Secretary was solicited by Shannon. Juan-Carlos Brevis of Enza Zaden USA was nominated by Joel Canestrino and the nomination was accepted.

For W2008 Meeting in Denver, December 12:
Chair-Brian Nault
Co-Chair-Joel Canestrino
Secretary-Juan-Carlos Brevis

As for the W2008 Meeting in 2014, it was decided by the NARC group that the 2014 NARC meeting will be held in conjunction with the NOA National Annual Meeting in Scottsdale, AZ (specific date and location not yet listed on the NOA website). The likely meeting period is the last week of November, perhaps spilling over into early December. Since the NARC meeting is often times hosted by a university researcher at a land-grant university involved in onion research, they typically organize the NARC meeting. Since, it will be in AZ and without a University host, it was decided a liaison committee from the NARC work with the NOA to organize the 2014 meeting. This liaison Committee will be comprised of the W2008 Officers and two volunteers. Thus, the NARC /W2008 2014 meeting organizers will be:

Joel Canestrino-Chair,Juan-Carlos Brevis-Co-Chair, To be elected-Secretary, Shannon Pike-Volunteer, Past Chair Bill Chounet-Volunteer and Past NARC Host.

Accomplishments

Objective 1. Evaluate onion germplasm for greater levels of tolerance to Iris yellow spot virus (IYSV), other pathogens and thrips. Colorado (H. Schwartz, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) - During 2012 the Colorado team reevaluated the following germplasm with significantly greater plant vigor after season-long exposure to thrips and the virus in 2011: selections from Plant Introduction (PI) lines 258956 (Calderana), 288909, 343049, 546188 (Winegar), dpSeeds Mesquite, Crookham 05-05, and B5336C (M. Havey selection from P53-364-2C). However, high temperature stress affected seedling development and survival, so the field experiment was abandoned; these and other promising lines will be evaluated as greenhouse-grown transplants under field conditions in 2013. New Mexico (C. Cramer) - Eighty-two onion breeding lines selected for IYSV tolerance, 18 plant introduction (PI) accessions from the U.S. germplasm collection, 11 experimental breeding lines from the New Mexico State University (NMSU) breeding program, and 9 commercial cultivars were evaluated for the number of thrips per plant, leaf color, leaf waxiness, IYS disease symptoms, and bulb yield. For those entries tested as transplants, numbers of onion thrips adults and larvae per plant were highest at 12 and 15 weeks post transplanting. Among those breeding lines selected for IYSV tolerance, plants of NMSU 10-577-1, NMSU 10-591-1, NMSU 10-593-1, NMSU 10-628-1, and NMSU 10-646-1 had lower thrips densities at 12 and 15 weeks than the susceptible check, Rumba. In addition to these selected lines, plants of PIs 172702, 172703, 239633, 258956, and 264320 also had fewer thrips than plants of Rumba. Of those entries tested, plants of 27 selected lines and 7 PI accessions were rated as having light to dark green leaf color. With regards to leaf waxiness, plants of 26 selected lines and 6 PI accessions were rated as having semi-glossy to glossy leaves. For those entries tested as transplants, plants of NMSU 10-591-1 and NMSU 10-593-1 exhibited a lower IYS disease severity at 12, 14, 16, and 18 weeks post transplanting than plants of Rumba. Plants of NMSU 10-575-1, NMSU 10-577-1, NMSU 10-582-1, NMSU 10-646-1, PI 239633, and PI 258956 exhibited a lower IYS disease severity at 14, 16, and 18 weeks post transplanting than plants of Rumba. NMSU 10-593-1 and NMSU 10-646-1 were selections made from PI 239633 and PI 258956, respectively. In addition, plants of NMSU 10-592-1 and NMSU 10-596-1 when evaluated at 14 weeks and plants of NMSU 10-589-1 and NMSU 10-629-1 when evaluated at 18 weeks had less severe disease symptoms than Rumba evaluated at those same dates. Plants of NMSU 10-591-1 exhibited no disease symptoms at 12 weeks that was lower than the disease incidence of plants of Rumba. At 14 weeks post transplanting, plants of NMSU 10-575-1, NMSU 10-593-1, NMSU 10-596-1, and NMSU 10-629-1 exhibited a lower disease incidence than plants of Rumba that exhibited 100% disease incidence. By 16 weeks, disease incidence had reached 100% for all entries. For those entries tested as transplants, NMSU 10-592-1, NMSU 10-593-1, NMSU 10-620-1, NMSU 10-632-1, NMSU 10-643-1, and PI 239633 exhibited a colossal market class bulb yield that was greater than the yield of other entries. With regards to jumbo bulb yield, NMSU 10-607-1, NMSU 10-632-1, NMSU 10-643-1, NMSU 10-646-1, NMSU 10-658-1, NMSU 10-708, and PI 264320 exhibited a jumbo bulb yield that was greater than the yield of other entries. Individual plants, that exhibited few IYS disease symptoms, were selected at bulb maturity from 45 different selected lines, 7 NMSU experimental breeding lines, and 6 PI accessions for a total of 169 bulbs. These bulbs are being pollinated in the hopes of finding progeny that possess a higher level of IYS tolerance. Seed was produced from 59 unique selections made in the previous year. These 59 unique lines have received two cycles of selection for resistance to IYS. These 59 lines originated from 34 first generation selection lines that in turn originated from 16 unique lines that were first evaluated during the summer of 2008. Progress for resistance to IYS in these 59 unique lines will be determined in 2013. Seed of numerous first generation selection lines was produced in 2012 so that seed could be distributed to the onion seed industry for evaluation. New York (B. Nault) - An IPM program for onion thrips that combines a partially thrips-resistant cultivar and insecticide applications timed using action thresholds was evaluated in a commercial onion field near Elba, NY in 2012. Dry bulb onion seeds, cv Santana (thrips susceptible) and cv Advantage (partially thrips resistant), were planted on 1 May. Season total densities of onion thrips in untreated plots were similar between Advantage and Santana. Thrips pressure was higher in Santana plots than Advantage plots early in the season, but higher in Advantage plots than Santana plots later in the season. Onion thrips were controlled effectively in both Advantage and Santana plantings following either the weekly insecticide spray program or the action threshold program. However, half the number of insecticide applications was applied in the action threshold program compared with the weekly spray program for both cultivars. Marketable bulb yield for Advantage was significantly greater than bulb yield for Santana, indicating that the yield potential for Advantage is greater than Santana. For Advantage, there were only minor differences in marketable bulb yield among the three insecticide treatments, indicating that despite significant differences in thrips densities between treated and untreated planting, this cultivar exhibits tolerance to thrips. In contrast for Santana, marketable yield in untreated plots was significantly lower than in treated plots. Perhaps, the reason for the negative effect of thrips feeding on Santana yield has something to do with greater pressure earlier in the development of the crop. Oregon (C. Shock, S. Reitz, E. Feibert, and M. Saunders) - Two early-season yellow varieties and 49 full-season varieties (40 yellow, 6 red, and 3 white) were evaluated for maturity and severity of thrips leaf damage in 2012. Plots were harvested and during grading, bulbs were separated according to quality including those with neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). Varieties varied in thrips damage, botrytis, plate rot, black mold, but not IYSV. Four onion varieties were grown at five plant populations under conventional drip irrigation, intense bed drip irrigation, and furrow irrigation. Varieties, populations, and irrigation systems were not related to IYSV or bulb decomposition. Bulb yields by market class were strongly affected by variety and plant population. Populations interacted with irrigation systems to cause a small amount of bulb decomposition, with more bulb decomposition at 160,000 plants per acre with furrow irrigation (1.1%) and intense beds (1.4%) than with conventional drip irrigation (0%). Utah (D. Drost) Twenty-eight commercially available Spanish onion cultivars were assessed for productivity, maturity and rated for IYSV. Symptom expression of IYSV in 2012 was very low; however, all varieties evaluated showed visual evidence of IYSV under field conditions. Severity in 2012 was not high enough to impact onion bulb yield. Further evaluation of storage materials will occur in February 2013 to assess losses. Work on correlations between IYSV incidence and storage needs further evaluation. Wisconsin (M. Havey) - Onion bulbs that appeared least affected after evaluation under thrips and IYSV pressure in Colorado in the summer of 2011 were planted in Wisconsin and seed produced by selfing individual plants, or mass pollinations among two to four plants (depending on the vigor of the bulbs after storage and vernalization). Selected plants were also testcrossed to a susceptible male-sterile line. Due to excessive temperatures and poor pollinator survival, seed production was very poor on these plants. If more than approximately 50 seeds were produced, they were provided back to H. Schwartz (CSU) for re-evaluation. Plants producing fewer than 50 seeds will be planted in Wisconsin for bulb production and seed increase. An F2 family from the cross of semi-glossy (reduced epicuticular waxes) and waxy (wild-type phenotype) was evaluated for amounts and types of epicuticular waxes. The lower waxy phenotype is associated with lower damage by thrips and IYSV. Over 300 single nucleotide polymorphisms (SNPs) were mapped in this cross to tag gene(s) associated with lower waxes on leaves. Objective 2. Investigate thrips biology and IYSV epidemiology to improve management strategies. Colorado (H. Schwartz, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) - During 2012, onions were monitored during leaf development and bulb expansion for the presence of thrips and IYSV. Thrips numbers increased from 1 to more than 60 per plant in commercial fields; and over 300 thrips per plant in experimental nurseries, where IYSV incidence reached 100% with a severity of 3.5 of 4. A Vaquero seed treatment comparison revealed that IYSV incidence reached 100% in all plots, but IYSV severity (1 4) was lower for Vaquero + T/C/A/S (3), followed by Vaquero + T/C/A (3.5), when compared to Vaquero + T (4). Total yield was higher for Vaquero + T/C/A/S (73 percent), followed by Vaquero + T/C/A (57 percent), when compared to Vaquero + T [T = Thiram, C = Coronet (pyraclostrobin + boscalid), A = Allegiance (metalaxyl), S = Sepresto (clothianidin]. The jumbo yield component was also doubled by the seed treatments when compared to the Vaquero + T only. Cyantraniliprole and Vydate (oxamyl) reduced larval and/or adult onion thrips populations on transplanted and seeded onions under experimental conditions in the field. Live thrips adults and larvae were recovered during the 2010-2011 and 2011-2012 winters from onion cull piles, onions left standing in the field, and Malva neglecta (common mallow) despite temperatures that fell below freezing. IYSV was detected by RT-PCR in these thrips, indicating that IYSV infected thrips surviving the winter are a likely source of inoculum for the next growing season. Temperature and thrips activity in onion culls were monitored in subsequent months during fall of 2011 and winter of 2011-2012. Temperature changes in the cull piles were more gradual and less dramatic than those of the outside air. The internal temperature of cull piles was conducive to thrips survival, however, very few live thrips were found after the onset of onion decay within the cull piles. Thrips activity was monitored by sticky traps around the cull piles and thrips were active until early December 2011 when the outside temperature fell below -17° C. Reducing thrips populations can sometimes help reduce infection rate of IYSV in onions. In Colorado, companion crops (living mulch) such as barley and spring wheat planted with onions to reduce wind and water erosion, has sometimes had an effect on thrips populations. The objectives of this 2012 study were to determine: which thrips predators and parasites inhabit the barley or spring wheat companion crop and what other insects/arachnids dwell in this living mulch; if there is a relationship between predator/parasite and thrips populations; if there is a relationship between thrips populations and IYSV incidence and severity; and if there is a relationship between predator/arachnid populations and onion market yields. Two farm locations had both companion crop and non-companion crop treatments replicated four times. Up to six beneficial predator and parasite families and seven plant feeding arthropod families were identified from both field locations. There were numerically more thrips and beneficial arthropods in the companion crop treatment compared with the non-companion crop treatment. There were significantly more beneficial populations in the companion crop treatment than the non-companion crop treatment at one field location. There was a positive trend between thrips populations and IYSV incidence at both locations. Numbers of thrips per plant, incidence and severity of IYSV, and onion market yields in the companion crop treatment did not differ from those in the non-companion crop treatment at either location. An observation made more than thirty feet from an onion field where thrips were seen flying six to 10 feet above the ground in the early morning hours, leads us to believe that the size of the onion plots used were too small to truly measure the impact of the companion crop on thrips and beneficial population dynamics. Future work should incorporate large scale plot design to better determine what effect companion crops like mulch has on thrips and beneficial population dynamics. Oregon (C. Shock, S. Reitz, E. Feibert, and M. Saunders) - Fifteen insecticide rotations plus an untreated control were evaluated for their effectiveness in controlling thrips and IYSV. Thrips populations and onion bulb yield varied significantly between treatments, suggesting that thrips were a limiting factor. Movento and Agri-mek were effective in early season thrips control. Lannate and Radiant were effective in mid to late season thrips control. Other materials (Aza-direct, M-Pede) may help early in the season. Onions grown with the fifteen insecticide rotations and the untreated control did not vary in IYSV symptoms in 2012. Alternatives to conventional pesticides such as combinations of Mycotrol O, kaolinite clay, and diatomaceous earth were tested, but they were not successful in controlling thrips. Idaho (S.K. Mohan) - Five sentinel plots in selected commercial onion fields in the Treasure Valley were monitored periodically throughout the growing season for incidence and severity of IYS and infestation levels of onion thrips. Samples collected every two weeks were evaluated for IYSV and other disease symptoms and thrips. IYSV symptoms were first observed in the third week of June but incidence was very low (less than 1%) until the second week of August, after that point the incidence increased to 80% plants infected by the end of August. Generally low numbers of thrips (6 to 29 thrips/plant) were observed in the beginning of June, increasing with time and reaching high levels (up to a maximum of 290/plant) by August. Thrips samples collected were sent to Colorado State University for identification of the thrips species involved and to determine the percent carrying IYSV. New York (S. Beer, M. Fuchs, C. Hoepting, and B. Nault) Foliar-applied insecticides that performed best against onion thrips in 2012 included spinetoram (Radiant SC), spirotetramat (Movento), cyantraniliprole (Benevia) and abamectin (Agri-Mek SC). A Section 18 for Movento was granted by EPA in 2012 in New York; Benevia should receive a Section 3 label in 2013. Co-applications of insecticides (Agri-Mek and Movento) with chlorothalonil fungicides (Chloronil) reduced thrips control by 25 to 48% compared with control levels provided by the insecticides alone in several trials. Inclusion of a penetrating surfactant at recommended rates with the insecticide and chlorothalonil fungicide mixture did not consistently overcome this problem. Co-applications of insecticides with other commonly used fungicides did not interfere with thrips control. To manage onion thrips in onion most effectively, insecticides should be applied with a penetrating surfactant, and should be applied separately from chlorothalonil fungicides. Season-long management of onion thrips was provided using a series of products beginning with Movento (2 applications) followed by Agri-Mek (2 applications), Lannate (2 applications) and Radiant (2 applications). Movento, Benevia and Agri-Mek were most effective controlling onion thrips when applied following a 1 thrips larva per leaf threshold. When combining the sequence of products listed above with this action threshold, the total number of applications used during the season was reduced from 17 to 58%. In mid-July 2010, onion plants cv. Candy with typical IYSV symptoms were found in New Holland, Lancaster County, PA. Leaf tissue from five symptomatic plants tested positive for IYSV using ELISA. The presence of IYSV was verified by RT-PCR in a subset of symptomatic leaf samples. Sequence analysis of a 402 bp DNA amplicon showed an 87 to 100% nucleotide sequence identity with other IYSV N gene sequences that are available in GenBank. The highest nucleotide sequence identity (100%) was with an IYSV isolate from Texas (GenBank Accession No. DQ658242) and the lowest was with an isolate from India (GenBank Accession No. EU310291). This finding confirmed further spread of IYSV within North America. Utah (D. Alston, D. Drost and C. Nischwitz) Field crops and weeds growing in proximity to onion fields and onion plants and onion thrips were sampled during main cropping season (May-Sept) and tested for their role as alternate hosts or the presence of IYSV. Samples were analyzed using ELISA kits. By identifying plants in the farmscape surrounding onion fields that serve as virus reservoirs and onion thrips reproductive hosts, these plants could be targeted and treated or removed thus reducing the amount and source of IYSV inoculum near onion fields. Preliminary results showed that alfalfa and several weeds tested positive for IYSV. Crop fields (corn, wheat, alfalfa) adjacent to onion fields harbored onion thrips in varying amounts and most were reproductive hosts for thrips. Thrips and crop tissue testing is on-going as significant numbers of samples were collected. Sustainable, profitable onion production occurs when seasonal inputs (planting dates, nutrients, water), onion thrips (control strategies), and IYSV are properly managed. Several onion growers in Utah have noted improved thrips management and reduced IYSV severity through alternative crop rotations and improved nitrogen management. Our research has shown that these alternative cultural practices reduce thrips numbers thus altering IYSV incidence with minimal impact on onion productivity. The goals of a six year university study are to determine the effects of unique crop rotations and improved nitrogen management strategies on thrips populations; to evaluate crop rotations and nitrogen (N) inputs on onion yield and quality; and to disseminate our findings through extension bulletins, the Internet, trade journals and scientific literature to onion producers (local, regional, national and international audiences). Washington (T. Waters) - Six research trials evaluated insecticide efficacy for thrips control in dry bulb onions. The goals of the trials were to determine which insecticides best control onion thrips, and the timing during the season in which to use those compounds for best efficacy. 3. Investigate the biology, ecology and epidemiology of other pathogens to improve management strategies Colorado (H. Schwartz, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) - Disease incidence of pink root was decreased by nearly 30% with treatments of Serenade and TerraClean, compared to 20% more discolored roots in the Quadris treatment. Average weight prebulbing of roots and basal plates was increased by 10% (TerraClean) to 19% (Serenade Soil, Quadris) with the treatments, compared to the untreated control. Total and jumbo yield components were also increased by the treatments. Total yield was increased 11, 16 and 31%; and the jumbo yield component was increased 11, 32 and 75% by Quadris, TerraClean and Serenade, respectively. Botrytis infection was detected in 3 to 74% of transplanted bulbs or 39 to 80% of seeded bulbs in storage rot experiments during 2012. A sequential fungicide program combined with good curing practices reduced the 60-day loss from Botrytis in the yellow and red transplanted onions; and in the white seeded onions. Georgia (R. Gitatis) The mean percentage of thrips that tested positive for Pantoea ananatis after acquisition periods (on peanut leaves) 1, 6, 12, 24 and 48-h tested positive for P. ananatis was 0, 4.2, 25.0, 45.9 and 70.8, respectively. A positive exponential relationship between acquisition access period and mean percentage of P. ananatis positive-thrips was observed. Bacterial colonies were not recovered from thrips that fed on PBS-inoculated-peanut leaves. After being exposed for 72-h to epiphytic populations of P. ananatis, the bacterium persisted in 70.8, 50.0, 33.3, and 33.3% of thrips after 0, 6, 24, 48, and 96 hpe to healthy peanut leaves respectively. Even after 120 and 168 hpe to healthy peanut leaves, P. ananatis persisted in 16.7 and 4.2% of thrips. The relationship between persistence period and percentage of P. ananatis-positive thrips was better represented by an exponential decay regression model. P. ananatis populations were not recovered from negative control thrips assayed similarly. One hundred percent of the onion seedlings that were inoculated with P. ananatis displayed typical center rot symptoms after 5 days post inoculation. Seedlings inoculated with sucrose solution remained asymptomatic. Sixty four percent of onion seedlings that were inoculated with thrips-feces developed center rot symptoms. A subset of seedlings associated with each treatment that led to putative center rot symptoms was confirmed to be infected with P. ananatis by pathogen isolation followed by real time PCR assay. Immunolabeled micrographs of F. fusca showed bacterial localization in the head, thorax, hind gut and hemolymph after 48-h of acquisition access period. Pantoea ananatis cells were not observed in the sections of negative control thrips. Onion plants exposed to individuals of T. tabaci fed either Pna or Png developed typical center rot symptoms. In two independent trials, 60.0 and 75.0% of the seedlings exposed to bacteria-fed thrips developed center rot symptoms, respectively. Identities of bacteria isolated from suspect lesions were confirmed. An exponential positive relationship between thrips acquisition access periods and Pna or Png acquisition existed with 100 and 91.7% of the thrips acquiring Pna and Png, respectively. These results demonstrate the potential of T. tabaci to serve as a vector of either Pna or Png. New York (S. Beer and C. Hoepting) - Based on microbiological and molecular biological techniques, the most important bacteria associated with symptomatic growing and unmarketable onion bulbs from storage in NY were identified as Burkholderia cepacia, Pantoea ananatis and Enterobacter cloacae. Several other bacteria of the genera Pseudomonas, Burkholderia, Pantoea and Rahnella also were identified. Several of the isolated strains of Rahnella species were inoculated into apparently healthy onion bulbs. They caused symptoms similar to those caused by E. cloacae. Thus, further research is in progress to determine the pathogenic properties of the Rahnella strains, since this bacterium had not been established previously as a plant pathogen. A technique aimed at identifying bacteria associated with onions quickly and without first isolating and purifying bacterial cultures was developed. The PCR-based technique uses novel rigorously identified and highly specific primer pairs for amplification of specific bacteria affecting onion including Pantoea ananatis, Enterobacter cloacae, Burkholderia spp. and Rahnella spp. Approximately 100 samples of muck-land soils were collected close to onion-planting time from fields in which onions were planted or had grown. Variations of the techniques used for onion samples were developed for use with muck soils. These samples generally yielded evidence of the presence of the important bacterial pathogens of onion encountered in the symptomatic growing onions and cull onion bulbs assayed earlier. Thus, muck-land soil was implicated as the source of over-wintering bacterial pathogens of onion. Additionally, ditch and creek waters at the periphery of muck-land onion fields were collected and assayed for the presence of important bacterial pathogens of onion in NY. A spray trial was carried out in a commercial onion field designed to evaluate the potential of registered resistance-inducing materials to effect bacterial disease development. Spray trials also were carried out in commercial onion fields designed to evaluate the effect of spray adjuvants, of different types, on the development of bacterial disease of onion. Preliminary results indicate that above label rates of adjuvants containing organosilicones can cause significant leaf injury, which in turn resulted in higher incidence of bacterial bulb decay. Further research in this area is warranted. A large observational survey was conducted in NY to elucidate the most important factors driving bacterial diseases of onions grown in muck soil. Three sub-plots were set up in 32 fields consisting of six varieties in five locations with nine onion growers. Factors including crop rotation, planting configuration, onion thrips damage, soil compaction, soil and tissue nitrogen, and yield will be correlated with bacterial bulb decay. Preliminary results from 2011 showed the strongest positive correlation between available soil nitrate-nitrogen in mid-July at the 7-9-leaf stage and incidence of bacterial bulb decay. Extensive data analysis planned for these data sets in 2013. An on-farm small-plot field trial was conducted to evaluate the effect of row and plant spacing, and area per bulb on bacterial bulb decay. Thirteen planting configurations were evaluated using in transplanted onions, c.v. Candy, in mineral soil. Incidence of bacterial bulb decay was very low (< 4%) in this trial and there were no significant differences among treatments. However, preliminary data suggests that plant spacing is a stronger predictor of yield and bulb size than row spacing or bulb area. Further research under higher disease pressure is warranted. Pennsylvania (B. Gugino) Survey plots for bacterial pathogens were established in 30 onion fields on 30 farms in Pennsylvania in 2012. Average farm losses ranged from 0 to 15% at harvest and 6 to 64% out of storage. Warmer mid-season soil temperatures and visual disease ratings were positively correlated to in-field losses from bacterial disease at harvest. More losses also occurred when onions were grown on black as opposed to white plastic; however, this practice is not recommended due to increased pressure from thrips. The bacterial pathogens commonly associated with center rot at harvest were also found as epiphytes and endophytes on onion transplants as well as epiphytes on weeds while the bacteria that cause surface rots were more commonly associated with soils. The efficacy of alternative in-season products for managing onion bacterial diseases was evaluated in two field trials. The treatments consisted of variable rates and combinations of the following applied either as a soil drench at planting or an in-season foliar spray: copper hydroxide tank mixed with mancozeb (grower standard for bacterial diseases), hydrogen dioxide (OxiDate), acibenzolar-S-methyl (Actigard), Bacillus subtilis GB03 (Companion) as well as harpin ±² protein (Employ). Onion transplants cv. Candy were planted on standard black plastic with a double row of drip irrigation. Based on the results, the standard grower practice of preventative applications on copper hydroxide tank mixed with mancozeb is still recommended for management of bacterial diseases of onion and should be used in combination with other cultural practices for managing bacterial diseases. Washington (L. du Toit and B. Schroeder) - Impact of the onion postharvest curing process (temperature and duration of curing) on development of bulb rots caused by Burkholderia cepacia and B. gladioli pv. alliicola, causal agents of sour skin and slippery skin of onion bulbs, respectively, was investigated. Onion bulbs were harvested from grower fields for two cultivars, inoculated with B. cepacia or B. gladioli pv. alliicola, cured at 25, 30, 35, or 40°C for 2 or 14 days, placed in storage at 5°C, and evaluated for bacterial rot after 1, 2, and 3 months in storage. As curing temperature increased, for both durations of curing, each pathogen caused greater severity of rot. Results indicate stakeholders should attempt to cure bulbs at lower temperatures, or avoid long durations of curing if higher curing temperatures are used. In addition, a DNA macroarray for the detection and differentiation of 14 fungi, 12 bacteria, and 1 yeast capable of causing onion bulb rots in storage is being developed to include oligonucleotide sequences specific for each target pathogen. Currently, genus-specific oligos have been designed for Botrytis, Penicillium, and Fusarium; and species-specific oligos have been developed for Aspergillus flavus, Kluyveromyces marxianus, Fusarium oxysporum, Botrytis aclada, B. allii, and B. byssoidea. The oligos for Aspergillus, B. cinerea, B. squamosa, and various Penicillium species are being redesigned because of problems with cross-reaction to non-target fungi. Oligos specific for the bacterial pathogens B. gladioli, Pantoea agglomerans, Pseudomonas marginalis, Pseudomonas aeruginosa, Pectobacterium carotovorum, and Dickeya dadantii have been developed. For detection of some onion bacterial pathogens, cross-reaction problems have been encountered, so a combination of oligos is being developed to detect the B. cepacia complex consisting of B. ambifaria, B. cenocepacia, B. cepacia, and B. pyrrocinia; a second combination of oligos is being developed to detect Pantoea ananatis, P. alli, and Salmonella enterica; and a third combination to detect Erwinia rhapontici and E. persicina. Efforts to increase the specificity of these oligos are in progress. Finally, oligos for detection of Enterobacter cloacae and Pseudomonas viridiflava are in the process of being redesigned. Objective 4. Facilitate interaction and information transfer between W2008 participants, the onion industry and other stakeholders. New York (S. Beer, C. Hoepting, and B. Nault) - Several meetings were held in 2012 to inform NYs onion industry about results from this project: the Empire State Fruit and Vegetable EXPO in Syracuse in January, the Orange County Onion School in Middletown in March, the Oswego Twilight Meeting in Oswego in June, the Annual Summer New York Onion Industry Council Meeting near Sodus in July and the Elba Muck Onion Meeting in Elba in August. Information pertaining to this subject was also presented at the National Allium Research Conference and W2008 Meeting in Las Cruces, NM in December and at the Annual Entomological Society of America Meeting in Knoxville, TN also in December. Cooperative Extension Educators worked with 3 growers and scouted 6 onion fields. Each week, onion thrips and diseases were quantified and summarized into a weekly scouting report, which included Cornell research-based recommendations for insecticides and fungicides. Through these on-farm demonstrations, onion growers observed research-based recommendations in action and were able to make informed spray decisions. All farms saved on insecticide sprays by following spray thresholds, compared with a weekly calendar approach. Pest activity reports and research-based recommendations were made to onion growers via a weekly newsletter, Veg Edge Weekly. Similarly, several newsletter articles regarding strategic management of onion thrips and progress towards managing bacterial diseases of onions were published in the monthly issue of Veg Edge. The majority of large-scale onion growers had access to these newsletter articles. Pennsylvania (B. Gugino) Research results were disseminated at several vegetable grower meetings/conferences including the Northeast Vegetable Growers Meeting and New Holland Vegetable Day. Results were also disseminated throughout the season through one-on-one with the growers collaborating in the intensive field survey project. Participated in the Onion ipmPIPE and continued to disseminate the Diagnostic Pocket Series to interested growers and other stakeholders. Oregon (C. Shock, S. Reitz, E. Feibert, and M. Saunders) - The project has continued to effectively transfer information pertinent to IYSV and thrips biology to growers, other onion industry parties, and the public through numerous meetings, field days, publications, and the internet. Results have been effectively communicated by grower and fieldman participation in the project planning and evaluation of results, field days for growers July 11, 2012 and August 27, 2012, grower meetings on February 7, 2012, internet web sites, and results being reported in Onion World. Utah (D. Alston, D. Drost and C. Nischwitz) For the Onion ipmPIPE project, 5 sentinel plots/survey sites were monitored in the Davis, Weber, and Box Elder County production onion areas in Utah by Bonnie Bunn in 2012. Fields were evaluated from early June until early September for thrips, other insects, and IYSV. Reports were submitted periodically, along with regional reports summarizing weather conditions, Sentinel Plot reports, growth observations, and other insect and disease comments. Several meetings were held in 2012 to inform Utahs onion industry about results from this project. These included the Utah Onion Associations winter educational meetings (Feb. 14), the summer onion field day (Aug 16), and the fall Utah Onion Associations board meeting (Nov. 14). Washington (L. du Toit, B. Schroeder and T. Waters) Interaction and information transfer among W2008 participants from Washington State University (WSU) and the Pacific Northwest onion industry was facilitated by the WSU Onion Field Day held on August 30, 2012, where growers heard reports from researchers and extension personnel working on various onion projects, and by sharing results of the 2012 WSU Onion Cultivar Trial with stakeholders at the Pacific Northwest Vegetable Association (PNVA) Annual Convention and Trade Show on November 14-15, 2012. Bulbs harvested from the WSU Onion Cultivar Trial were on display at the PNVA conference. In addition, stakeholders participated in storage evaluation on February 10, 2012 of bulbs harvested for all the cultivars grown in the 2011 WSU Onion Cultivar Trial and stored for 4 months. Results of the cultivar trial and storage evaluations were shared with the PNW onion industry.

Publications

Bag, S., Schwartz, H.F., and Pappu, H.R. 2012. Identification and characterization of biologically distinct isolates of Iris yellow spot virus (genus Tospovirus, family Bunyaviridae), a serious pathogen of onion. Eur. J. Plant Pathol. 134:97-104. Beer, S.V., Asselin, J.E., Bonasera, J.M., Zaid, A.M. and Hoepting, C.A. 2012. Better understanding of bacterial onion diseases in New York. Onion World, Columbia Publishing, 28(4): 18-23. Beer, S.V., Asselin, J., Bonasera, J., Zaid, A. and Hoepting, C.A. 2012. Understanding bacterial diseases of onion in New York. Veg Edge, 8(5): 17-20. Cramer, C.S., Mohseni-Moghadam, M., Creamer, R.J., and Steiner, R.L. 2012. Screening winter-sown entries for Iris yellow spot disease susceptibility, pp. 80-99. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. Diaz-Montano, J., Fail, J., Deutschlander, M., Nault, B.A. and Shelton, A.M.. 2012. Characterization of resistance, evaluation of the attractiveness of plant odors, and effect of leaf color on different onion cultivars to onion thrips (Thysanoptera: Thripidae). J. Econ. Entomol. 105(2): 632-641. Diaz-Montano, J., Fuchs, M., Nault, B.A. and Shelton, A.M. 2012. Resistance to onion thrips (Thysanoptera: Thripidae) in onion cultivars does not prevent infection by Iris yellow spot virus following vector-mediated transmission. Florida Entomol. 95(1): 156-161. Foley, K.M., Doniger, A.R., Shock, C.C., Horneck, D.A., and Welch, T. 2012. Nitrate Pollution in Groundwater, Sustainable Agriculture Techniques, Oregon State University, Department of Crop and Soil Science Ext/CrS 137. Hoepting, C. A., and Beer, S.V. 2012. Exploring the relationship between nitrogen plant spacing and bacterial diseases of onion in NY: Reduced nitrogen and closer spacing could result in less rot. Onion World, Columbia Publishing, 28(7): 18-21. Hoepting, C.A., and Fuchs, M. 2012. First report of Iris yellow spot virus on onion in Pennsylvania. Plant Disease 96:1229. Hsu, C.L., Hoepting, C.A., MacNeil, C.R. and Nault, B.A. 2012. How low can you go? The economics of controlling onion thrips with reduced inputs, 2 pgs. In: Proceedings of the 2012 Empire State Fruit & Vegetable EXPO. January 24-26, 2012. Syracuse, NY. http://www.hort.cornell.edu/expo/proceedings/2012/Onions/onion%20Hsu.pdf Nault, B.A. 2012. Onion thrips control in onion, 2011. Arthropod Management Tests, 2012. 37: E35. Nault, B.A. 2012. Onion thrips management in onion, 5 pgs. In: Great Lakes Fruit, Vegetable and Farm Market EXPO. Educational Program Abstracts. December 5, 2012. Grand Rapids, MI. Michigan State University Extension. http://www.glexpo.com/summaries/2012summaries/onion.pdf Nault, B.A., Hsu, C., and Hoepting, C. 2012. Consequences of co-applying insecticides and fungicides for managing Thrips tabaci (Thysanoptera: Thripidae) on onion. Pest Management Science. DOI 10.1002/ps.3444 Nault, B.A., and Shelton, A.M. 2012. Guidelines for managing onion thrips on onion. Cornell Cooperative Extension, Cornell Vegetable Program. Veg Edge 8(5): 14-17. Nault, B.A., and Shelton, A.M. 2012. Guidelines for managing onion thrips on onion. Cornell Cooperative Extension. Cornell Cooperative Extension of Orange County. Muck & Mineral June 2012: 1-5. Nault, B.A., Shelton, A.M, Hsu, C. and Hoepting, C. 2012. How to win the battle against onion thrips. Onion World. March/April 2012. pp. 14-17. Nault, B. A., A. M. Shelton, C. L. Hsu and C. A. Hoepting. 2012. How to win the battle against onion thrips, 6 pgs. In: Proceedings of the 2012 Empire State Fruit & Vegetable EXPO. January 24-26, 2012. Syracuse, NY. http://www.hort.cornell.edu/expo/proceedings/2012/Onions/onion%20Nault.pdf Rodriguez-Salamanca, L.M., Enzenbacher, T.B., Derie, M.L., du Toit, L.J., Feng, C., Correll, J.C., and Hausbeck, M.K. 2012. First report of Colletotrichum coccodes causing leaf and neck anthracnose on onions (Allium cepa) in Michigan and the United States. Plant Disease 96: 769. Schroeder, B.K., Humann, J.L., and du Toit, L.J. 2012. Effects of postharvest onion curing parameters on the development of sour skin and slippery skin in storage. Plant Disease 96: 1548-1555. Shock, C.C., and Shock, C.B. 2012. Research, extension, and good farming practices improve water quality and productivity. Journal of Integrative Agriculture 11(1): 14-30. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. 2011 Onion Variety Trials. p 12-23 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2011, Department of Crop and Soil Science Ext/CrS 141. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. Onion Production from Transplants. p 24-31 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2011, Department of Crop and Soil Science Ext/CrS 141. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. Onion Production from Sets, 2011. p 32-39 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2011, Department of Crop and Soil Science Ext/CrS 141. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. Response of Four Onion Varieties to Plant Population and Irrigation System. p 40-65 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2011, Department of Crop and Soil Science Ext/CrS 141. Smith, E. A., A. DiTommaso, M. Fuchs, A. M. Shelton and B. A. Nault. 2012. Abundance of weed hosts as potential sources of onion and potato viruses in western New York. Crop Protection 37: 91-96. Waters, T.D., and Walsh, D. 2012. Thrips control on dry bulb onions in Washington State, 2011. Arthropod Management Tests 37. http://www.entsoc.org/protected/AMT/AMT37. Wohleb, C.H., Waters, T.D., du Toit, L.J. and Schroeder, B.K. 2012. The Washington State University Onion Cultivar Trial: An important resource for Washington onion growers. Acta Horticulturae 969:241-246. http://www.actahort.org/books/969/969_32.htm Zaid, A.M., Bonasera, J.M., Beer, S.V. 2012. OEM -- A new medium for rapid isolation of onion-pathogenic and onion-associated bacteria. J. Microbiological Methods 91: 520526. Other Activities 1. Research Reports: Abstracts and Papers at International Professional Meetings Fok, E.J., and Nault, B.A. 2012. Natural enemies of onion thrips (Thrips tabaci) in New York onion agroecosystems. Entomological Society of America Annual Meeting. November 12, 2012. Knoxville, TN. Nault, B.A., and Shelton, A.M. 2012. Proactive IRM for thrips: A case study of onion thrips in onion. In Section Symposium: Do crises drive innovation? Insect Resistance Management: Proactive or Reactive? Entomological Society of America Annual Meeting. November 13, 2012. Knoxville, TN. Pfeufer, E.E., Mansfield, M.A., Stoltzfus, J. and Gugino, B.K. 2012. Identification of factors associated with bacterial diseases of onion: A case study of two Pennsylvania farms. Phytopathology 102: S1.7. (Abstract) Schwartz, H.F., Schroeder, B.K., VanKirk, J., Douce, G.K., Jibilian, G., Lafferty, J., and Norton, G.W. 2012. Onion ipmPIPE Network Interactive resource for onion stakeholders. American Phytopathological Society Annual Meeting. August 4-8, 2012. Providence, RI. Phytopathology 102:S4.107. (Abstract). Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. Onion bulb size response to plant population for four varieties under three irrigation systems. American Society of Horticultural Science. Miami, FL. Smith, E.A., Shields, E.J., Fuchs, M. and Nault, B.A. 2012. Early-season patterns of onion thrips, Thrips tabaci (Lindeman), population densities in onion fields in New York. Entomological Society of America Annual Meeting. November 12, 2012. Knoxville, TN. Vahling-Armstrong, C.M., Humann J.L., Lupien, S., Dugan, F., du Toit, L.J., and Schroeder, B.K. 2012. DNA macroarray for the detection of fungal onion bulb rot pathogens. American Phytopathological Society Annual Meeting. August 4-8, 2012. Providence, RI. Phytopathology 102:S4.125. (Abstract). 2. Research Reports: Abstracts and Papers at National Professional Meetings Beer, S.V., Asselin, J.E., Bonasera, J.M, Zaid, A.M., Hoepting, C.A. 2012. Research yields greater understanding of bacterial diseases of onion in New York. http://www.hort.cornell.edu/expo/proceedings/2012/Onions/Onions%20Beer.pdf Cramer, C.S. Screening winter-sown onion entries for Iris yellow spot virus resistance. W2008: Biology and management of Iris yellow spot virus (IYSV), other diseases and thrips in onions. Regional research project annual meeting. Dec. 14, 2012. Las Cruces, NM. Cramer, C.S., Mohseni-Moghadam, M., Creamer, R.J., and Steiner, R.L. Steiner. 2012. Screening winter-sown entries for Iris yellow spot disease susceptibility, pp. 39. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. (Abstr.) Cramer, C.S., Muhyi, R., Mohseni-Moghadam, M., Kamal, N., and Singh, N. 2012. Eight years of screening for Iris yellow spot resistance, p. 31. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. (Abstr.) Damon, S., and Havey, M.J. 2012. Genetic variation for epicuticular waxes in onion: a thrips-avoidance mechanism. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Drost, D. 2012. Does alternative crop management practices impact thrips, IYSV and onion productivity? Proc. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Poster Presentation. Feibert, E.B.G., Shock, C.C., Saunders, L.D., and Simerly, B. 2012. An overview of onion production from transplants and sets. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Fok, E., and Nault, B.A. 2012. Natural enemies of onion thrips (Thrips tabaci) in New York onion agroecosystems. Entomological Society of America Eastern Branch. March 17, 2012. Hartford, CT. Havey, M.J., Cramer, C.S., Pappu, H.R., Schwartz, H.F., Chan, A., and Town, C. 2012. USDA-SCRI funded project Ensuring US onion sustainability: Breeding and genomics to control thrips and Iris yellow spot virus, p. 32. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. (Abstract) Hoepting, C.A. 2012. An IPM approach to managing bacterial diseases of onions. In: Proceedings of the 2012 Great Lakes Fruit, Vegetable and Farm Market EXPO (online): http://www.glexpo.com/summaries/2012 summaries/onion.pdf. December 4-6, 2012. Grand Rapids, MI. Hoepting, C.A. 2012. Exploring the relationship between nitrogen and bacterial diseases of onions. In: Proceedings of the 2012 Empire State Fruit and Vegetable Expo, Cornell Cooperative Extension and New York State Vegetable Growers Association (online): http://www.hort.cornell.edu/expo/proceedings/2012/Onions/Onion%20Nitrogen%20and%20Bacterial%20Hoepting.pdf. January 24-26, 2012. Syracuse, NY. Hoepting, C.A., Nault, B.A., and Beer, S.V. 2012. W2008: New York update for managing onion thrips and bacterial diseases of onions. Annual Meeting for Multi-State Project W2008: Biology and Management of Iris yellow spot virus (IYSV), Thrips and Other Diseases in Onions. December 14, 2012. Las Cruces, NM. Kamal, N., and Cramer, C.S.. 2012. Selection progress for thrips and Iris yellow spot virus resistance in onion germplasm after one selection cycle, p. 47. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. (Abstract) Nault, B.A. 2012. Onion insect pest management in onion. Great Lakes Fruit, Vegetable & Farm EXPO. Michigan State University Extension. December 5, 2012. Grand Rapids, MI. Poudyal, D.S., du Toit, L.J., Paulitz, T., Porter, L., Eggers, J., and Hamm, P. 2012. Onion stunting caused by Rhizoctonia: Management and economic importance in the Columbia Basin of Oregon and Washington. National Allium Research Conference, 12-14 Dec. 2012, Las Cruces, NM. http://aces.nmsu.edu/narc2012/index.html Abstract and proceedings article (pp. 68-77). Reitz, S., Shock, C.C., Feibert, E.B.G., Jemmett, E., and Saunders, L.D. 2012. Insecticide rotations for control of thrips in onion. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Schroeder, B.K., Vahling-Armstrong, C.M., Humann J.L., Knerr, A.J., Lupien, S., Dugan, F., and du Toit, L.J. 2012. DNA macroarray for the detection of fungal onion bulb rot pathogens. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Abstract. Schwartz, H.F., Schroeder, B.K., VanKirk, J.G. Douce, K., and Jibilian, G. 2012. Update on the onion ipmPIPE network Progress and plans. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Abstract. Shock, C.C., Feibert, E.B.G., and Reitz, S. 2012. Oregon 2012 update on IYSV and thrips. W2008 Annual Meeting. December 14, 2012. Las Cruces, NM. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. 2012. Plant population options for marketing long-day onions. National Allium Research Conference. December 12-13, Las Cruces, NM. Singh, N., and Cramer, C.S. 2012. Selection progress for tolerance to Iris yellow spot virus in onions, p. 43. In: Proc. 2012 Natl. Allium Res. Conf. S. Walker and C.S. Cramer (Eds.), Las Cruces, NM. (Abstract) Smith, E.A., Shields, E.J., Fuchs, M. and Nault, B.A. 2012. Early-season patterns of onion thrips, Thrips tabaci (Lindeman), population densities in onion fields in New York. Entomological Society of America Eastern Branch. March 17, 2012. Hartford, CT. Waters, T.D. 2012. Thrips Control Strategies on Onion. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Wohleb, C.H., Waters, T.D., du Toit, L.J., and Schroeder, B.K. 2012. The WSU Onion Cultivar Trial: A Valuable Resource for Pacific Northwest Onion Producers. National Allium Research Conference. December 12-13, 2012. Las Cruces, NM. Abstract. 3. Reports at Grower meetings and field days Alston, D., Nischwitz, C., and Drost, D. 2012. USU ipmPIPE Thrips/IYSV monitoring protocols and ipmPIPE and onion website information. Utah Onion Association Summer Field Tour. August 16, 2012. Layton, Utah. Alston, D. 2012. Novel Insecticides for Onions. Utah Onion Association winter Summer Field Tour. August 16, 2012. Layton, Utah. Armstrong, C., Humann, J., Knerr, J., du Toit, L. J., and Schroeder, B.K. 2012. Development of a DNA Macroarray for rapid detection of onion bulb rot pathogens. Washington State University Onion Field Day. August 30, 2012. Beer, S.V. 2012. Progress towards managing bacterial diseases of onions. 2012 Annual Elba Muck Onion Twilight Meeting, Cornell Vegetable Program. August 2, 2012. Elba, NY. Bunn, B. and D. Alston. 2012. Utah Onion ipmPIPE Project: Thrips Monitoring in the Onion Landscape. Utah Onion Association winter meeting. February 14, 2012. Brigham City, Utah. Cramer, C.S. 2012. Screening onion entries for tolerance/resistance to Iris yellow spot virus. NM Onion Field Day. July 21, 2012. Las Cruces, NM. Drost, D. 2012. 2012 Onion Variety Trial Results Better than Expected. Utah Onion Association winter meeting. February 14, 2012. Brigham City, Utah. Drost, D. 2012. Onion Crop Rotation Study. Utah Onion Association Summer Field Tour. August 16, 2012. Layton, Utah. du Toit, L.J. 2012. Disease management in onion seed crops: What, when, and how? Central Oregon Farm Fair & Trade Show. February 1-2, 2012. Madras, OR. du Toit, L.J. 2012. Effective management of Botrytis in onion seed crops. Annual Educational Growers Meeting of the Specialty Seed Growers of Western Oregon. February 22, 2012. Albany, OR. du Toit, L.J. 2012. Management practices to reduce stunting caused by Rhizoctonia. 52nd Annual Meeting of the Idaho & Malheur County, Oregon Onion Growers Associations. February 7, 2012. Ontario, OR. du Toit, L.J. 2012. Rhizoctonia in onion bulb crops: Evaluation of field management practices. Columbia Basin Crop Consultants Association Annual Short Course. January 18, 2012. Moses Lake, WA. du Toit, L.J. 2012. Steps towards effective management of Botrytis in onion seed crops. Columbia Basin Vegetable Seed Association Annual Meeting. January 17, 2012. Moses Lake, WA. du Toit, L.J., and Poudyal, D.S. 2012. Rhizoctonia control in dry bulb onions. Pacific Northwest Vegetable Association 26th Annual Conference & Trade Show. November 14-15, 2012. Kennewick, WA. du Toit, L.J., Poudyal, D.S., Paulitz, T., Porter, L., Hamm, P., and Eggers, J. 2012. Rhizoctonia seedling blight of onion crops in the Columbia Basin. Pp. 8-9 in: 2012 WSU Onion Cultivar Demonstration and Field Day Handout. Washington State University, Pullman, WA. Gugino, B.K. 2012. Growing onions: Options for disease management. Schuylkill County Ag Day and Trade Show. February 9, 2012. Schuylkill Haven, PA. Gugino, B.K. 2012. Onion disease management. Northeast Vegetable Growers Meeting, Newton Ransom Fire Company. January 26, 2012. Clarks Summit, PA. Gugino, B.K. 2012. Onion disease management. New Holland Vegetable Day, Yoders Restaurant. January 16, 2012. New Holland, PA. Foley, K.M., Doniger, A.R., Harden, J.L., Parris, C.A., and Shock, C.C. 2012. Technology for Yourth. Summer Farm Festival, OSU Malheur Experiment Station. July 11, 2012. Ontario, OR. Hoepting, C.A. 2012. Onion program update featuring bacterial diseases of onions. Cornell Cooperative Extension of Wayne County Board of Directors Meeting. September 4, 2012. Newark, NY. Hoepting, C.A. 2012. Field demonstration: Exploring the role of adjuvants in the development of bacterial diseases of onions. 2012 Annual Elba Muck Onion Twilight Meeting, Cornell Vegetable Program. August 2, 2012. Elba, NY. Hoepting, C.A. 2012. Exploring the relationship between nitrogen and bacterial diseases of onion in New York. 2012 Empire State Fruit and Vegetable Expo, Cornell Cooperative Extension and New York State Vegetable Growers Association. January 26, 2012. Syracuse, NY. Hoepting, C.A. 2012. An IPM approach to managing bacterial diseases of onion. Great Lakes Fruit, Vegetable and Farm Market EXPO. December 5, 2012. Grand Rapids, MI. Hoepting, C.A. 2012. Exploring the relationship between nitrogen and bacterial diseases of onions. Oswego Onion Twilight Meeting, Cornell Cooperative Extension of Oswego County. Oswego, NY, USA: June 18, 2012 (38 attendees). Hsu, C.L., C. A. Hoepting, C. R. MacNeil and B. A. Nault. 2012. How low can you go? The economics of controlling onion thrips with reduced inputs. Empire State Fruit & Vegetable EXPO. January 26, 2012. Syracuse, NY. Speaker. Duration: 20 minutes. Attendance: 60. Nault, B. A. 2012. Field demonstration of managing onion thrips. 2012 Elba Muck Onion Twilight Meeting. Cornell Cooperative Extension, Cornell Vegetable Program. Elba, NY. August 2, 2012. Nault, B. A. 2012. Considerations for managing maggots and thrips in onions. Oswego County Onion Twilight Meeting. Cornell Cooperative Extension of Oswego County. Oswego, NY. June 18, 2012. Nault, B. A. 2012. Insect management for 2012 maggot and thrips control. Orange County Onion School. March 1, 2012. Middletown, NY. Speaker. Duration: 60 minutes. Attendance: 50. Nault, B.A., Shelton, A.M., Hsu, C.L., and Hoepting, C.A. 2012. How to win the battle against onion thrips. Empire State Fruit & Vegetable EXPO. January 26, 2012. Syracuse, NY. Speaker. Duration: 45 minutes. Attendance: 60. Nischwitz, C. 2012. Thrips Food Sources and IYSV Hosts in the Utah Farmscape. Utah Onion Association winter meeting. Brigham City, Utah. February 14, 2012. Schroeder, B.K., Vahling-Armstrong, C., Humann, J.L., Knerr, A.J., and du Toit, L. J. 2012. Development of a DNA Macroarray for the Detection of Bulb Rot Pathogens of Onion. Pacific Northwest Vegetable Association Annual Conference. November 14-15, 2012. Kennewick, WA. Schwartz, H.F. 2012. Onion disease management and updates. Annual Education Meeting of the Colorado Crop Consultants Association. January 11, 2012. Denver, CO. Schwartz, H.F. 2012. Onion virus management and updates. Annual Education Meeting of the Colorado Onion Association. January 26, 2012. Eaton, CO. Schwartz, H.F. 2012. Onion virus management and updates. Annual Education Meeting of the Wisconsin Onion Association. February 1, 2012. via Skype. Shock, C.C. 2012. Onion Thrips Control. Idaho/Malheur County, Oregon Onion Growers 52nd Annual Meeting. February 7, 2012. Ontario, OR. Shock, C.C. 2012. Progress on Cleaning up Groundwater through BMPs. Idaho/Malheur County, Oregon Onion Growers 52nd Annual Meeting. February 7, 2012. Ontario, OR. Shock, C.C. 2012. Onion Production Tour. Summer Farm Festival, OSU Malheur Experiment Station. July 11, 2012. Ontario, OR. Shock, C.C. 2012. Water Quality and Farm Practices. Summer Farm Festival, OSU Malheur Experiment Station. July 11, 2012. Ontario, OR. Shock, C.C., and Feibert, E.B.G. 2012. Irrigation Criteria and Systems for Onions. Pacific Northwest Vegetable Association. November 14, 2012. Kennewick, WA. Shock, C.C., and Feibert, E.B.G. 2012. Onion varieties, production, and thrips control. Onion Variety Day. OSU Malheur Experiment Station. August 28, 2012. Ontario, OR. Shock, C.C., Feibert, E.B.G., and Saunders, L.D. 2012. Onion Plant Population Studies. Pacific Northwest Vegetable Association. November 14, 2012. Kennewick, WA. Shock, C.C., Klauzer, J., and Neufeld, J. 2012. Irrigation Water Management with Dataloggers and Soil Moisture Sensors. Treasure Valley Irrigation Conference. December 6, 2012. Nampa, ID. Ward, R. 2012. Onion Budgets Do Small Changes in Practice Affect the Bottom Line? Brigham City, Utah. February 14, 2012. Waters, T.D. Thrips Control in Sweet Onions. Walla Walla Farmers Co-Op Grower Meeting. January 17, 2012. Walla Walla, WA. Waters, T.D. Insect Management in Onions. Columbia Basin Crop Consultants Annual Short Course. January 18, 2012. Moses Lake, WA. Waters, T.D. Onion Thrips Management in Onions. Utah Onion Grower Annual Meeting. February 14, 2012. Brigham City, UT. Waters, T.D. Thrips Control Strategies on Onion. Far West Agri-Business Association Annual Meeting. December 11, 2012. Pasco, WA. Waters, T.D., and Walsh, D. Thrips Control in Dry Bulb Onions. Pacific Northwest Insect Management Conference. January 8, 2012. Portland, OR. Waters, T.D., and Walsh, D. Thrips Control Strategies for Onions. Pacific Northwest Vegetable Association. November 14, 2012. Kennewick, WA. Waters, T.D., and Wohleb, C. 2012. Washington State University Onion Cultivar Storage Demonstration Trial. February 10, 2012. Pasco, WA. Internet Resources Schwartz, H.F. 2012. Web site dedicated to information and resources on onion pest management and/or thrips and IYSV. http://www.alliumnet.com/index.htm Onion Disease Management strategies, reports and publications, including those on IYSV and thrips and other diseases. http://www.colostate.edu/Orgs/VegNet/vegnet/onions.html Onion ipmPIPE and Disease Diagnostics, including those on IYSV and thrips, in addition to other resources such as weather, forecasts, markets: http://apps.planalytics.com/aginsights/pipehome.jsp http://onion.coop/ Schwartz, H.F., and Gent, D. H. 2012. High Plains Integrated Pest Management Resource. On-line IPM bulletin with updated onion disease and pest reviews, and pesticide recommendations. http://wiki.bugwood.org/HPIPM%3AOnion Information on onions and pest management is posted on the website of the Regional Cornell Cooperative Extension Vegetable Program in New York: http://cvp.cce.cornell.edu/ http://mtvernon.wsu.edu/path_team/onion.htm#thrips http://mtvernon.wsu.edu/path_team/onion.htm#irisyellowspot

Impact Statements

Outputs of this work posted on web sites and presented at various meetings will be used by the Colorado and national onion industries, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective management strategies including the promotion of varieties that are less susceptible to damage by thrips and the virus.
Germplasm was identified that possessed foliage characteristics that are associated with onion thrips feeding nonpreference. In addition, germplasm was identified that possessed a reduced number of thrips per plant than the untreated control. Both of these characteristics suggest that there is the genetic potential for reduced thrips feeding and possibly reduced Iris yellow spot virus spread. Selection for reduced thrips number and IYS disease severity appears to be effective Germplasm was identified that possessed foliage characteristics that are associated with onion thrips feeding nonpreference. In addition, germplasm was identified that possessed a reduced number of thrips per plant than the untreated control. Both of these characteristics suggest that there is the genetic potential for reduced thrips feeding and possibly reduced Iris yellow spot virus spread. Selection for reduced thrips number and IYS disease severity appears to be effective
Pantoea ananatis transmission to healthy onion plants may be a passive process that occurs through tobacco thrips (F. fusca) feces in the vicinity of feeding wounds rather than by regurgitation and active feeding. P. ananatis do not colonize the gut of F. fusca and after prolong feeding on healthy tissues bacteria are purged from the gut. Thrips can cleanse their digestive system by feeding on a non-contaminated food supply for at least 196 h.
This study demonstrated that onion thrips (T. tabaci) are also capable of transmitting center rot bacteria P. ananatis and P. agglomerans. In fact, onion thrips appear to be even a more efficient vector. Thus a shift in population from tobacco thrips to onion thrips may have the potential of increasing center rot incidence in Georgia. It also demonstrates that in other areas of the world where T. tabaci dominates as the pest species on onion, there is the potential of onion thrips serving as a vector of center rot bacteria.
In New York, on-farm demonstrations of managing onion thrips with research-based recommendations with regards to sequences, thresholds and tank mix considerations, resulted in reducing the number of sprays used to control onion thrips by 20 to 50%, representing savings of $40 to $120 per acre in reduced input costs.
In Oregon, more growers are adopting onion varieties with greater tolerance to IYSV and are irrigating in a manner that seems to reduce IYSV severity. Fewer growers are planting over-wintering onions and are disposing of cull onions, breaking the natural green bridge for IYSV so that IYSV levels are reduced from one production year to the next. Growers are using Movento early in the season and getting adequate control.
Growers in Utah who used lower nitrogen levels (130-150 lb. N/A) applied 4-5 fewer insecticide sprays, saving them nearly $200/A compared with growers using the normal N input amounts of >250 lbs of N/A. Lower N use also saves on fertilizer costs at a time when N prices are increasing for an additional savings of around $100/A. We estimate that more than 350 acres of onions in Utah are now being grown using lower N level system recommended by Utah State University.

Date of Annual Report: 01/22/2014

Report Information

Annual Meeting Dates: 12/12/2013 - 12/12/2013
Period the Report Covers: 10/01/2012 - 09/01/2013

Participants

Julie Kerr
Larry Moir
Larry Schild
Jake Walker
David Drews
Mark Milenski
Jeff Hoffner
Larry Duell
Ron Carleton
John Salazar
Laura Quakenbush
Tanya Fell
Whitney Cranshaw
Howard Schwartz
Thaddeus Gourd
Michael Bartolo
Jeffrey Steiner
Artie Geisick
Lanny Huston
Jeff Riley
Felix Barron
Kevin Miller
Elizabeth Plummer
Juan Carlos Brevis
Shannon Pike
Wayne Stewart
Rod Weimer
Justin Butcher
Larry Jensen
Patrick McBride
Ralph Anders
Lyndon Johnson
Clint Shock
Stuart Reitz
Chris Cramer
Mark Uchanski
Beth Gugino
Joe Petrocco
Dave Petrocco, Sr.
Alan Foutz
Ian Lyle
Robert T. Sakata
James Thompson
Pete Forester
Gordon Hankins
Tom Turini
Bhabesh Dutta
Ron Gitaitis
Brenda K. Schroeder
Tim Waters
Gauray Raikhy
Olufemi J. Alabi
Tyler Morfitt
Darlene Maxwell
Wayne Mininger
Kim Reddin
David Whitwood
Dan Drost
Christy Hoepting
Steve Beer
Brian Nault

Participants Attachment:

Attachment

Brief Summary of Minutes

Accomplishments

Objective 1. Evaluate onion germplasm for greater levels of tolerance to Iris yellow spot virus (IYSV), other pathogens and thrips. Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – During 2013, the Colorado team reevaluated the following germplasm with significantly greater plant vigor after season-long exposure to thrips at Fort Collins: selections from MSU611AxMSU611-1B 22665, 22684, 22720 and 22724. Bulbs have been sent to Mike Havey for potential use in genetic and molecular marker studies with IYSV and thrips resistance; and include PI 261591, 264320, 264648, 274780, 288903, 288909, 546096, 546101, 546106, 546140, 546188, 546192, and 546201. New Mexico (C. Cramer) - Eighty-eight onion breeding lines selected for reduced IYSV disease symptom expression, 7 plant introduction (PI) accessions from the U.S. germplasm collection, 8 experimental breeding lines from the New Mexico State University (NMSU) breeding program, and 3 commercial cultivars were evaluated for the number of thrips per plant and IYSV disease symptoms. Adult and juvenile onion thrips number per plant was highest at 13 and 16 weeks post transplanting. Among those breeding lines selected for reduced IYSV symptom expression, plants of 33, 37, and 25 lines possessed fewer thrips at 10, 13, and 16 weeks after transplanting, respectively, than plants of the susceptible checks, ‘Rumba’ and ‘Vaquero’. For those lines that were selected from PI 172703, plants of seven second generation lines had fewer thrips than plants of PI 172703 when thrips were counted at 10 weeks. At 13 weeks, plants of nine second generation lines has fewer thrips per plant than plants of PI 172703. For those lines that were selected from PI 546140, plants of NMSU 12-295 had fewer thrips than plants of PI 546140 when thrips were counted at 10 weeks. Among those breeding lines selected for reduced IYSV symptom expression, plants of 13 lines exhibited less severe IYSV disease symptoms than plants of the susceptible checks, ‘Rumba’ and ‘Vaquero’ at 13 and 16 weeks after transplanting. At 13 and 16 weeks, plants of second generation lines, NMSU 12-335 and 12-342, exhibited less severe disease symptoms than plants of their parental lines, NMSU 07-32-2 and 07-56-2, respectively. At 13 weeks, plants of NMSU 12-236 exhibited a lower disease severity than plants of its parental line, NMSU 07-52-1. At 16 weeks, plants of second generation lines, NMSU 12-239 and 12-243, exhibited less severe disease symptoms than plants of their parental line, NMSU 07-53-1. In addition, plants of NMSU 12-285 exhibited less severe disease symptoms than plants of its parental line, PI 289689. At 19 weeks, plants of NMSU 12-335 and 12-243 exhibited less severe disease symptoms than plants of their parental lines, NMSU 07-32-2 and 07-53-1. Eleven selected lines exhibited a lower IYSV disease incidence than the susceptible checks, ‘Rumba’ and ‘Vaquero’ at 13 weeks after transplanting. Selected lines, NMSU 12-236 and 12-335, exhibited a lower disease incidence percentage than their parental lines, NMSU 07-52-1 and 07-32-2, respectively. By 16 weeks, disease incidence had reached 100% for all entries. Seed of numerous first generation selection lines was produced this year so that seed could be distributed to the onion seed industry for evaluation. New York (B. A. Nault, S. V. Beer and C. A. Hoepting) - An onion thrips management program that combines a partially thrips-resistant cultivar (cv. ‘Advantage’) and insecticide applications timed using action thresholds was evaluated in a commercial onion field in 2013. Season total densities of onion thrips in untreated plots were similar between ‘Advantage’ and the thrips-susceptible cultivar, ‘Santana’. Onion thrips were controlled effectively in both ‘Advantage’ and ‘Santana’ plantings following either a weekly insecticide spray program or an action threshold program. However, fewer insecticide applications were applied in the action threshold program compared with the weekly spray program, especially for ‘Advantage’. Marketable bulb yield for ‘Advantage’ was similar between the insecticide treatments and untreated control, indicating that despite significant differences in thrips densities between treated and untreated planting, this cultivar exhibits tolerance to thrips. In contrast for ‘Santana’, marketable yield in untreated plots was significantly lower than in treated ones. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) - In 2013 four early-season yellow varieties were planted in March and were harvested and graded in mid-August. Forty-nine full-season varieties (39 yellow, 3 red, and 7 white) were planted in March, harvested in September 2013, and graded out of storage in January 2014. Onions in each plot of the full-season trial were evaluated for maturity and for severity of symptoms of IYSV. Each plot was given a subjective rating on a scale of 0 to 5 of increasing severity of IYSV symptoms. During grading, bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with Botrytis allii in the neck or side), plate rot (bulbs infected with Fusarium oxysporum), and black mold (bulbs infected with Aspergillus niger). Varieties varied in Botrytis, plate rot, black mold, but not IYSV which was very low in field trials in 2013. Utah (D. Drost) - Twenty-nine commercially available Spanish onion cultivars were assessed for productivity, maturity and rated for IYSV. Symptom expression of IYSV in 2013 was very low; however, all varieties evaluated showed visual evidence of IYSV under field conditions. IYSV had little impact on onion bulb yield. Further evaluation of storage materials will occur in February 2014 to assess losses. Work on correlations between IYSV incidence and storage needs further evaluation. Objective 2. Investigate thrips biology and IYSV epidemiology to improve management strategies. Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – Research evaluations performed this year included a thrips and IYSV assessment. Thrips populations were counted on July 24 at the Sakata Farm near Brighton and August 7 at the CSU ARDEC Farm near Fort Collins, CO. The Sakata Farm trial averaged 3.3 thrips and the CSU ARDEC Farm averaged 12 thrips per onion plant. With only moderate levels of thrips, we did, however, experience a 99% plant infection rate of IYSV at both locations. The IYSV assessments of incidence and severity were taken on September 30 at the Sakata location and on September 25 at the CSU ARDEC location. The Sakata location experienced a 1.7 severity level and the CSU ARDEC location had a 3.8 severity level (0-4 scale with 0 = no damage and 4 = having over 25 medium to large lesions per leaf). This could also explain why the CSU ARDEC location did not see adequate sizing up of the onion bulbs. Sticky traps showed that thrips were active until mid-December (2012 and 2013) when the average temperature fell below 0°C. In 2012, activity resumed in early March. IYSV was detected by RT-PCR in live adult and larval thrips recovered from several field sources during the winters of 2010-2011, 2011-2012, and 2012-2013. Few live thrips were found after the onset of decay in onion cull piles. Live thrips were easily recovered from winter annual species. Five of these weed species have been grown from seed in the greenhouse and exposed to viruliferous thrips to further elucidate their role as green bridges. Of the five, IYSV has been detected in Tragopogon dubious (western salsify) and thrips larvae reared on this plant. Results indicate winter annuals play a role in onion thrips and IYSV over-winter survival, providing inoculum the next growing season. More than 3000 plants grown from seed have been tested for IYSV by DAS-ELISA; all the plants that remained thrips-free (2,762 plants) were negative for IYSV. DAS-ELISA tests of germinated seed did detect IYSV in the seed of some individuals. This seed lot was comprised of seeds collected from 59 individual IYSV-infected field-grown plants representing seven varieties of red, yellow, and white onions. Because Tospoviruses are not known to be seed transmitted, 50 seeds from 12 individual plants (three individuals from each of the varieties Granero, Salsa, Red Defender, and Pentium) are germinating and the resulting shoots of 7 of these 12 plants are being separated from the seed coat and tested for IYSV by RT-PCR. IYSV has been detected in the seed coats of Pentium and Red Defender individuals, while the corresponding shoots were negative. The two Granero individuals tested have been negative. Because the seed coat does not always separate cleanly from the endosperm the possibility that IYSV is present in the endosperm cannot be discounted, although we feel that this is highly unlikely. Idaho (S.K. Mohan) - Four sentinel plots in commercial onion fields in the Treasure Valley were monitored periodically from May to August for incidence and severity of IYSV and infestation levels of onion thrips. Samples collected every two weeks were evaluated for any disease symptoms (mainly for IYSV) and pests (mainly counting thrips populations). IYSV symptoms were first observed in the first week of July but incidence was very low (less than 1%) until the second week of August. After that point the incidence increasing up to 20% plants with symptoms in one of the plots by the third week of August. Generally low levels of thrips (2 to 7/plant) were observed at the end of May, increasing with time and reaching high levels (up to a maximum of 70/plant) by August. Thrips samples collected were sent to Colorado State University for identification of the thrips species involved and to determine the percent carrying IYSV. No significant incidence of any other pest or disease was observed. New York (B. A. Nault, S. V. Beer and C. A. Hoepting) - More adult onion thrips were captured dispersing in onion fields in August than in June. Thrips also tended to fly more around dusk than any other period during the day. Most of the thrips dispersing in onion fields were captured below 6ft, suggesting that most engage in trivial flight or plant to plant movement. However, onion thrips were captured above 6ft including some as high as 300ft above onion fields. In August, a significant percentage of these thrips tested positive for IYSV, including some captured at 300ft. Results indicate that both onion thrips and IYSV have the potential to spread long distances. There were many commercial onion fields in NY that were transplanted with onion plants initially grown in Arizona. Two of these fields, located 10 miles northwest of Elba where the nearest large commercial onion production occurs, became severely infected with IYSV. No transplanted fields in the Elba muck onion production area suffered serious symptoms of IYSV. More research is needed to determine if imported onion plants from Arizona are infected with IYSV before arriving in New York. Co-applications of insecticides (Agri-Mek, Movento and Radiant) with mineral oils (PureSpray Green and JMS Stylet oil) were equally effective for managing onion thrips as these insecticides co-applied with traditional penetrating surfactants like Induce and MSO. Season-long management of onion thrips continues to be most effective using a series of products beginning with Movento (2 applications) followed by Agri-Mek (2 applications), Lannate (2 applications) and Radiant (2 applications). Exirel should be available for many onion growing areas in 2014 and will be best applied after Movento; Exirel does not work as well late in the season. Use of action thresholds (1 larva per leaf) in spray programs in New York has consistently reduced the number of insecticide applications needed to manage thrips from 17 to 58%. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) - A field trial testing 20 insecticide regimes was established in 2013. Insecticides were applied to the foliage weekly for 8 weeks from late-May through mid-July. Thrips were monitored by counting thrips on 15 plants per plot. Plants were subjectively rated for thrips feeding damage and severity of IYSV infection. Onions were harvested and graded to determine yield. Thrips pressure was high throughout the season but there were significant differences among the insecticide regimes in terms of thrips and IYSV management and yield. Yield was significantly related to onion thrips pressure, with programs that maintained the best management of thrips during the middle of the season (late June-early July) tending to have the highest yields and greater proportions of colossal and supercolossal sized onions. A program to monitor for insecticide resistance in onion thrips was started in 2013. Feral thrips were collected from commercial fields and then exposed to insecticide treated onion foliage under laboratory conditions. Mortality was assessed after 24 and 48 hours of exposure. Results indicate that onion thrips populations remain highly susceptible to four commonly used insecticides, Agri-Mek, Movento, Lannate and Radiant. Utah (D. Alston, D. Drost and C. Nischwitz) - Sentinel plots/survey sites were monitored in the Davis, Weber, and Box Elder County production onion areas in Utah in 2013. Fields were evaluated from June until September for thrips, other insects, and IYSV. Bi-weekly reports were submitted, along with weather summary, Sentinel Plot reports, growth observations, and other insect and disease comments. Sustainable onion production occurs when inputs (planting dates, nutrients, water), onion thrips, and IYSV are properly managed. Onion growers in Utah report improved thrips management and reduced IYSV severity through alternative crop rotations and improved nitrogen management. Growers are using USU research findings to alter their production practices thus reducing thrips numbers and IYSV incidence with minimal impact on onion productivity. Growers in New York, Washington, and Idaho are also using these tactics to better manage insects and diseases. Field crops and weeds growing next to onion fields were sampled for IYSV and thrips during the 2013 onion season (May-Sept) and tested for the presence of IYSV. Finding alternative IYSV hosts in the farm landscape surrounding onion fields allows farmer the opportunity to treat or remove these plants thus reducing the amount and source of IYSV inoculum. Results show that alfalfa, corn, prickly lettuce, common mallow, and field bindweed tested positive for IYSV. Crop fields (corn, wheat, alfalfa) adjacent to onion fields harbored onion thrips in varying amounts and most were good reproductive hosts for thrips. Washington (H. R. Pappu, T. Waters, C. Wohleb, B. K. Schroeder, and L. J. du Toit) - Field plots of onion (cv. ‘Sabroso’ Nunhems) were established at the WSU Research Farm in Pasco, WA and grown using drip irrigation and standard grower practices for agronomic and pest management inputs excluding thrips treatments. Plots (7.5 feet wide and 30 feet long) were established in a random complete block design with four replications. Applications (except where specified) were made with a CO2 pressurized back pack sprayer applying 30 gallons of water carrier per acre at 35 psi. Efficacy was evaluated four or five days after applications by counting the number of immature and adult thrips per plant on 10 individual plants per plot in the field. All data for each sample date were analyzed by ANOVA and treatment means were compared to thrips population means from non-treated control plots in pairwise t-tests. At the end of the growing season, onion yield and size were evaluated for comparison among treatments. Using insecticides that are effective at controlling thrips increases yield and size class of dry bulb onions. Radiant and Lannate were found to be the most effective products while Movento, Benevia/Exirel, Torac and AgriMek provided good suppression of onion thrips. All of the sequential applications tested provided excellent season long control of thrips and if adopted by commercial growers could increase economic returns. Weekly applications are not always needed as shown on the sequences where applications were skipped either early during the season or at the middle of the season. It is important for growers to consider the mode of action of the different chemistries when integrating them into their control programs. Chemigation proved to be an effective way to apply Lannate, and Radiant. There is evidence that Movento, Torac, and Exirel may be effective by chemigation, but further work should be performed for confirmation. 3. Investigate the biology, ecology and epidemiology of other pathogens to improve management strategies Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – Disease incidence of Pink Root was not decreased by treatments with Serenade or Quadris in a nursery with low disease pressure and cool to moderate temperature conditions early to mid-season. Xanthomonas leaf blight infection (incidence and severity) was reduced by timely applications of bactericides such as Kocide 3000 and experimentals when compared to the untreated control which sustained 60 percent canopy damage by the end of the season. Botrytis infection was detected in 2 to 12 percent of transplanted bulbs in storage rot experiments during 2013. Fungicide treatments including Pristine, Priaxor or Merivon combined with good curing practices reduced the 60-day loss from Botrytis in the yellow transplanted onions. New York (B. A. Nault, S. V. Beer and C. A. Hoepting) - At least four different bacteria can cause rot and render onions unsalable in New York. These include Burkholderia spp. (sour skin), Enterobacter cloacae (Enterobacter bulb decay), Pantoea ananatis (center rot) and Rahnella spp. We developed two distinct methods to identify the bacteria associated with cull onions. In one, a method of analyzing a portion of a specific gene was developed. That particular gene is grossly similar in all bacteria, but it is distinct in all onion-associated bacteria that we examined. Using a special means of analyzing that gene portion allowed for identification of a dozen different bacteria (pathogens and non-pathogens) associated with cull onions. For the four specific bacterial pathogens mentioned above, we designed, developed, and tested pairs of primers that can be used in the Polymerase Chain Reaction (PCR) to detect the presence of one or more of the stated important bacterial pathogens. The method is applicable to the detection of bacteria in cull onions, onions growing in the field, water collected from onion fields and for the soils in which onions have been grown. Most of the important bacterial pathogens of onion previously had been detected in soils collected from onion fields prior to or soon after onions were planted in muck fields in the spring. Recently, several of the bacteria of interest were detected in some, but not all, the water samples collected from the vicinity of onion fields, including drainage ditches, creeks, cisterns and shallow wells. We evaluated the susceptibility of several onion cultivars to leaf lesions induced by inoculation with Pantoea ananatis. Significant differences were noted. However, when mature bulbs of several of the same cultivars were inoculated with the pathogen, no differences in the development of bulb symptoms were noted. Thus, further work is needed to develop a reliable assay for the relative susceptibility of different genotypes to bacterial pathogens. In 2013, we organized extensive trials of sprays of Actigard®, a resistance-inducing chemical, applied by spraying during the growing season, on resulting bacterial decay. Ten trials were carried out in Orange County and on the Elba Muck (Orleans and Genesee Counties). Four or five sprays were applied in each 2- to 5-acre field. In the control plots, no resistance inducer was applied, but all other aspects of crop management were similar. At harvest, three to five replicate samples of 100 bulbs each were hand-harvested and bagged. After typical storage for 6 to 12 weeks, each bulb was examined and rated for the presence of bacterial decay; most were cut to reveal any evidence of decay. Results indicated no evidence that the sprays of Actigard® resulted in differences in the percentage of bacterial decay in any of the 10 trials. Onion foliage diseases were also studied in NY. An on-farm, small-plot comparison of fungicides for control of onion leaf diseases was conducted, which included 21 treatments. Best material for managing Botrytis leaf blight was Bravo, which was closely followed by Merivon. Best material for managing Purple Blotch was Scala. Best materials for control of Stemphylium leaf blight were Luna Tranquility, Merivon and Fontelis followed by Pristine and Inspire Super. These results will be used to make research-based fungicide recommendations that will ensure that all leaf diseases of onions are managed effectively. A curious situation occurred during the 2013 growing season in NY where excessive leaf dieback and onions “dying standing up” was caused by Stemphylium leaf blight (SLB). Normally, SLB occurs as a secondary pathogen in onions invading plant tissue that is already compromised. What caused this disease to move from its usual backseat position as a secondary pathogen to the forefront as an aggressive pathogen is unknown. Based on recent history in Ontario, Canada with SLB, it is expected that SLB will be a regular contender in NY onion fields. Fortunately, Hoepting was able to identify some promising new fungicides to combat SLB in her 2013 on-farm, small-plot onion fungicide trial. Based on her results, it is expected that when fungicides with excellent activity against SLB are incorporated into the onion fungicide spray program, NY onion growers will never experience such severe SLB again. Adjuvants co-applied with insecticides were evaluated for their impact on fungal and bacterial diseases. Replacing penetrating surfactants like Induce and MSO with mineral oils (PureSpray Green and JMS Stylet oil) for managing onion thrips had no effect on the incidence of Botrytis leaf blight, purple blotch or bacterial rot diseases. However, significantly higher levels of Botrytis leaf blight occurred in treatments where onion thrips were controlled compared to those where they were not. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) - Studies were initiated to understand the movement of E. coli in water and soil and E. coli survival on onion bulbs. Onions of all treatments of all experiments discussed above were evaluated for plate rot, Botrytis, and black mold. Pennsylvania (B. Gugino) - In Pennsylvania in 2011 and 2012, replicated on-farm survey plots were established on 28 and 26 farms, respectively to identify potential sources of inoculum as well as production factors related to harvest disease incidence. The extensive dataset generated continues to be a source of new information. A total of 235 bacterial isolates were recovered from 192 samples of the four most common weed species (crabgrass, redroot pigweed, purslane and lambsquarters) collected from commercial onion fields in 2011. Nearly 60% of the culturable bacteria isolated were potential pathogens of onion. Pseudomonas marginalis was commonly cultured from all types of weeds, while Pantoea agglomerans was commonly associated with crabgrass and purslane. Pectobacterium carotovorum was common only to redroot pigweed. Based on pathogenicity tests, all the bacterial isolates from lambsquarters were able to cause onion bulb rots while other weeds were found to have mixed populations of pathogenic and nonpathogenic bacteria on their surfaces. By sampling common weeds near onion fields in 2011, it was shown that weeds are a potential source of bacterial inoculum that causes diseases in onion bulbs. A rep-PCR method was developed to track bacterial strains within the same bacterial species. This will enable us to further link bacterial isolates collected from the surface of transplants, weeds, and soil from the on-farm survey plots to those isolated from symptomatic onion bulb tissue at harvest or after storage and further facilitate the development of management strategies to reduce these potential sources of bacterial inoculum. At-planting and at-harvest soil nitrogen, leaf and bulb tissue nitrogen, soil temperature and other factors were analyzed in a multivariate linear regression model. A strong negative relationship between leaf tissue nitrogen at midseason and total harvest losses was suggested, while a positive relationship was also identified between pre-harvest soil temperatures and bacterial disease incidence. These results relate the importance of reducing soil temperatures through use of alternative plastic mulches, ensuring adequate soil fertility early in the season and taking measures to reduce the impact of inoculum sources in the production system. Two field trials were conducted to evaluate the effects of inoculum pressure and onion maturity at harvest on harvest and post-harvest losses due to bacterial disease. The goal was to provide growers with additional information on the relationship between the timing of harvest and bacterial disease losses post-harvest so they can make informed decisions about when to harvest fields under pressure from bacterial diseases. Seasonal observations have indicated that environmental conditions around the time of bulbing greatly influence disease development. Harvesting too early significantly reduces the proportion of jumbo and colossal sized bulbs but delaying harvest in fields with higher foliar disease ratings could lead to significant at-harvest losses of greater than 30%. Data from these initial field trials suggest that foliar disease ratings between 3 (one half of one leaf symptomatic) and 4 (one entire leaf bleached and wilting) on a 1 to 7 point scale may be a critical threshold to help growers determine when to harvest onions to maximize yield while minimizing bacterial disease losses at harvest. Washington (H. R. Pappu, T. Waters, C. Wohleb, B. K. Schroeder, and L. J. du Toit) - An onion pink root trial was completed near Pasco, WA to evaluate the potential for Serenade Soil to reduce the impact of this disease. The trial had a very severe outbreak of pink root, with 100% incidence of infection and severity averaging 72% (% of roots with pink root symptoms) in inoculated plots and 57% in non-inoculated plots. A single application (banded over the bed) of Serenade Soil at planting at 4 qt/acre, or three applications at 2 qt/acre (at planting, 3 weeks and 6 weeks after planting) did not reduce severity of pink root compared to the control plots. Average bulb weight was not affected by the Serenade Soil treatments either. The results indicate Serenade Soil may not help reduce the impact of pink root in onion bulb crops. In a greenhouse trial to assess potential beneficial effects of mycorrhizae in onions at reducing the impact of soilborne pathogens of onion, onion plants grown in soil inoculated with Rhizoctonia solani AG-8 averaged a height of 6 cm compared to 15 cm for plants in non-inoculated control soil (>50% reduction in plant height caused by R. solani). When soil was infested with a commercial mycorrhizal inoculum (BioTerra Plus from Plant Health LLC), plant height averaged 20 cm, which was significantly greater than the height of seedlings in the control soil, and demonstrated a beneficial effect of mycorrhizae even in the absence of a soilborne pathogen. When onions were grown in soil inoculated with both R. solani AG-8 and the mycorrhizae, plant height averaged 18 cm, which was significantly taller than plants in the control plots, and not significantly different than plant height in soil infested with mycorrhizae alone. Similar results were obtained with the repeat trial. The results suggest that inoculation of soil with mycorrhizae may not only enhance onion growth, but also provide some protection against adverse effects of the soilborne pathogen R. solani. Similar experiments are planned with onion pink root. In a preliminary survey of conventional and certified organic onion bulb crops in the Columbia Basin of central Washington in 2013, mycorrhizae were detected in onion roots in all of these crops, although to different degrees of root colonization. The survey indicated that mycorrhizae can establish readily in soils in which onion bulb crops are grown in the Columbia Basin, even following soil fumigation which is widely practiced in this region (an estimated 90% of fields in which onion bulb crops are grown in the Columbia Basin are fumigated every 2-3 years). Large-scale, grower-cooperator mycorrhizae inoculation trials are planned for 2014. A DNA macroarray was developed to detect the onion bulb rot fungi Aspergillus niger, Botrytis aclada, B. allii, B. byssoidea, B. cinerea, Fusarium oxysporum, F. proliferatum, Kluyveromyces marxianus var. marxianus as well as several species of Penicillium. The technology uses pathogen-specific oligonucleotides bound to a membrane. The membrane is then used to hybridize DNA that has been amplified by polymerase chain reaction (PCR) from plant samples, enabling detection of multiple target organisms at the same time. A macroarray for detection and identification of the major onion bulb rot pathogens would be a valuable tool to detect and differentiate causal organisms associated with bulb rots in storage. The fungal DNA macroarray is able to detect and differentiate the fungal pathogens when the DNA is obtained from pure cultures. This was accomplished by sequencing the ITS region obtained from fungal isolates across the genera listed above. These sequences were aligned which revealed genus-specific and species-specific oligos. The oligos were modified with a 5' tail of nucleotides to enhance the specificity and improve binding of the oligos to the nylon membrane support. The fungal DNA macroarray is able to specifically detect and differentiate the fungal bulb rot pathogens. The specificity of the fungal DNA macroarray was evaluated against nonpathogenic fungi commonly found in association with onion bulbs as well as fungal species closely related to the bulb rot fungi. The fungal DNA macroarray is quite sensitive with detection of fungal pathogens possible with attogram levels of pathogen DNA present in the original PCR reaction. The development of the bacterial DNA macroarray focused on the 12 bacteria capable of causing onion bulb rot in storage including: Burkholderia cepacia, B. gladioli, Pantoea agglomerans, P. allii, P. ananatis, Pectobacterium carotovorum, Enterobacter cloacae, Pseudomonas marginalis, Erwinia rhapontici, Dickeya dadantii, and Pseudomonas aeruginosa. The development of the bacterial DNA macroarray included amplification of a region of the 23S rDNA which was sequenced and analyzed to identify unique nucleotides for bacterial pathogens and design oligonucleotides specific for each organism. The oligos contained more than one polymorphism and range from 17- 30 nucleotides in length. The bacterial oligos were more specific and more sensitive if they were present as a dimer with a nucleotide spacer in between. Efforts have focused on optimizing the detection conditions to eliminate cross reaction among the target bacteria listed above as well as non-target organisms associated with onion bulbs. Currently, there is some cross reaction among the Pseudomonas strains on the bacterial DNA macroarray. It is not clear why this is occurring and it is being investigated. The sensitivity of the bacterial DNA macroarray has not been determined. The fungal DNA macroarray was able to detect the presence of fungal pathogens present in asymptomatic onion bulbs, suggesting that it could be used to predict the risk of storage rots. It has not been determined if the bacterial DNA macroarray can detect bacterial plant pathogens present in asymptomatic onion bulbs as latent infections. A second genome of Enterobacter cloacae, cause of Enterobacter bulb decay, was sequenced (manuscript in press). In addition, the genetic diversity E. cloacae isolates was demonstrated by a multi locus sequence analysis (MLSA) that there is strong phylogenetic support for the organisms isolated from different hosts to be in different clades. In addition, it appears that the isolates obtained from onion bulbs group with reference strains of another species, suggesting that these isolates are misidentified. Objective 4. Facilitate interaction and information transfer between W2008 participants, the onion industry and other stakeholders. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) - The project has continued to effectively transfer information pertinent to IYSV and thrips biology to growers, other onion industry parties, and the public through numerous meetings, field days, publications, and the internet. Results have been effectively communicated by grower and fieldman participation in the project planning and evaluation of results, field days for growers (July 10, and August 26, 2013), tour for the FDA (August 12, 2013), grower meetings (February 5, 2013), internet web sites, and results being reported in Onion World and the Capitol Press. Pennsylvania (B. Gugino) - In Pennsylvania research results were disseminated at several vegetable grower meetings/conferences including the 2013 Mid-Atlantic Fruit and Vegetable Convention and Lancaster Onion Co-op meeting as well as during the 4th Annual Discovery Day at the Southeast Agricultural Research and Education Center which is geared towards the media and legislators who are interested in learning more about agricultural research that directly impacts the Commonwealth. On a national level, results were presented by Emily E. Pfeufer, Ph.D. candidate, at the 2013 American Phytopathological Society meeting in Austin, TX in August 2013. Results were also disseminated throughout the season through one-on-one with the growers collaborating in the intensive field survey project. We continued to disseminate the Diagnostic Pocket Series as well as the Onion Health Management and Production bulletin to interested growers and other stakeholders. Utah (D. Alston, D. Drost and C. Nischwitz) - Participation in the regular Onion ipmPIPE project conference calls throughout the year. Sentinel plots/survey sites (26 sites) were monitored in the Davis, Weber, and Box Elder County production onion areas in Utah by our team. Fields were evaluated from early June till early September for thrips, other insects, and IYSV. Drost submitted reports along with regional weather conditions, Sentinel Plot reports, growth observations, and other insect and disease comments. Reported on varietal research provided to Utah growers (52 attendees) at the February 2013 winter onion meetings. Alston talked about ipmPIPE project, and Nischwitz provided growers with IYSV information. Growers (42) attending the summer onion field tour (Aug 2013) learned about sustainable onion production, and were provided with details of impPIPE information. Utah onion association met twice (Apr, Nov) where they were provided with national update of ipmPIPE. Drost gave two presentations at the W2008 Annual Meeting describing Utah based research findings.

Publications

Alston, D. G., Nault, B., Cranshaw, W. S., Hardin, J., Srinivasan, R., and Waters, T. 2013. Insects and their management. Pp. 49-56. In, Onion Health Management and Production. Schwartz, H. F. and Bartolo, M. E. (editors). Colorado State University Bull. Fort Collins, CO. Beer, S. V., Asselin, J.-A. E., Bonasera, Zaid, A. M., J. M. and Hoepting, C. A. 2012. Better understanding bacterial onion diseases in New York. Onion World 28: (4) 18-22. Birithia, R., S. Subramanian, H. R. Pappu, J. Muthomi and R. D. Narla. 2013. Analysis of Iris yellow spot virus (IYSV, genus Tospovirus) replication in vector and non-vector thrips species. Plant Pathology DOI: 10.1111/ppa.12057. Boateng, C. O., and Schwartz, H. F. 2013. Temporal and localized dynamics of Iris yellow spot virus within tissues of infected onion plants. Southwestern Entomologist: 38:183-199. Carr, E. A., Zaid, A. M., Bonasera, J. M., Lorbeer, J. W., and Beer, S. V. 2013. Infection of onion leaves by Pantoea ananatis leads to bulb infection. Plant Disease 97: 1524-1528. Cramer, C.S. 2013. Onion germplasm selected for resistance to Iris yellow spot. N.M. Agric. Expt. Stn. Rel. Not. 5 pp. du Toit, L.J., Derie, M.L., and Waters, T.D. 2014. 2013 Onion pink root Serenade Soil efficacy trial in Pasco, Washington. Research report submitted to Dean Christie, Bayer CropScience, in Feb. 2014. 5 pp. du Toit, L.J., Poudyal, D.S., Paulitz, T., and Linderman, R. 2013. Preliminary survey for mycorrhizae in organic and conventional onion bulb crops in the Columbia Basin. Pp. 12-13 in: 2013 WSU Onion Cultivar Demonstration and Field Day Handouts. Washington State University, Pullman, WA. du Toit, L.J., Poudyal, D.S., Paulitz, T., Porter, L., Hamm, P., and Eggers, J. 2013. Rhizoctonia seedling blight in onion crops in the Columbia Basin. Pp. 10-11 in: 2013 WSU Onion Cultivar Demonstration and Field Day Handouts. Washington State University, Pullman, WA. Iftikhar, R., S. Bag, M. Ashfaq and H.R. Pappu. 2013. Occurrence of Iris yellow spot virus infecting onion in Pakistan. Plant Disease 97:1517. Keller, D. 2013. 2013 WSU Onion Cultivar Demonstration and Field Day: Assessing and Countering Potential Downside of Fumigation. Pages 10-13 in the Nov. 2013 issue of Onion World, Columbia Publishing, WA. Keller, D. 2013. Pacific Northwest Vegetable Association Conference & Trade Show: Pink Root in Times of Stress. Pages 10-13 in the Dec. 2013 issue of Onion World, Columbia Publishing, WA. Knerr, A.J., Humann, J.L., du Toit, L.J., Schroeder, B.K., and Armstrong, C. 2013. Advancement in Molecular Techniques for Rapid Identification of Onion Bulb Rot Pathogens: Development of a Bacterial DNA Macroarray. 2013 WSU Onion Cultivar Demonstration and Field Day Handouts. Muñoz, R. M., Lerma, M. L., Lunello, P., and Schwartz, H. F. 2013. Iris yellow spot virus in Spain: incidence, epidemiology and yield effect on onion crops. J. of Plant Pathology accepted Nault, B. A. 2013. Integrated pest management of onion thrips, 4 pages. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA. January 30, 2013. Nault, B. A., C. Hsu and C. Hoepting. 2013. Consequences of co-applying insecticides and fungicides for managing Thrips tabaci (Thysanoptera: Thripidae) on onion. Pest Management Science. 69: 841-849. Pappu, H.R., and A. Rauf. 2013. First report of Iris yellow spot virus in Indonesia. Plant Disease 97:1665. Patzek, L.J., du Toit, L.J., Paulitz, T.C., and Jones, S.S. 2013. Stunting of onion caused by Rhizoctonia spp. isolated from the Columbia Basin of Washington and Oregon. Plant Disease 97:1626-1635. Pfeufer, E.E., M.A. Mansfield, and B.K. Gugino. 2013. Environmental and management factors associated with bacterial rots of onion in Pennsylvania. Phytopathology 103:S2.173. Schwartz, H. F. (editor). 2013. Onion Health Management and Production. 104 pp. Colorado State University Bulletin, Fort Collins, CO. Sharma-Poudyal, D., Paulitz, T., Porter, L., Eggers, J., Hamm, P., and du Toit, L.J. 2013. Effect of timing of glyphosate application to a winter cover crop on stunting of spring-sown onions caused by Rhizoctonia spp. in the Columbia Basin of Washington, 2012. Plant Disease Management Reports 7:V046. Sharma-Poudyal, D., Paulitz, T., Porter, L., Eggers, J., Hamm, P., and du Toit, L.J. 2013. Efficacy of fungicides to manage onion stunting caused by Rhizoctonia spp. in the Columbia Basin of Oregon and Washington, 2011-2012. Plant Disease Management Reports 7:V047. Sharma-Poudyal, D., Paulitz, T., Porter, L., Eggers, J., Hamm, P., and du Toit, L.J. 2013. Yield responses of three onion cultivars to stunting caused by Rhizoctonia spp. in the Columbia Basin of Oregon and Washington, 2012. Plant Disease Management Reports 7:V048. Waters, T., and Wohleb, C. 2013. Onion Thrips. Washington State University Extension Fact Sheet FS126E, Pullman, WA. Webb, K. M., Case, A. J., Brick, M. A., Otto, K. and Schwartz, H. F. 2013. Cross pathogenicity and vegetative compatibility of Fusarium oxysporum isolated from sugar beet. Plant Disease 97:1200-1206 dx.doi.org/10.1094/PDIS-11-12-1051-RE. Wu, M., Goto, H., Waters, T.D., Walsh, D., & Lavine, L.S. 2013. Identification of an alternative Knockdown Resistance kdr-like mutation, M918L, and a novel mutation, V1010A, in the Thrips tabaci voltage-gated sodium channel gene. Pest Management Science. Zaid, A. M. and Beer, S. V. 2014. Detection of Burkholderia cepacia in onion planting materials and onion seeds. Chapter 22 in M. Fatmi and N. W. Schaad, eds. APS Manual on Detection of Plant Pathogenic Bacteria in Seed and Planting Material. 2nd Ed. APS Press. St. Paul, MN. (In Press). Other Activities 1. Research Reports: Abstracts and Papers at International Professional Meetings du Toit, L.J. Neck rot identification and management based on Achilles’ heel. Invited presentation, The UK Onion and Carrot Conference & Exhibition, 20-21 Nov. 2013, Peterborough, UK. (~350 people). du Toit, L.J. Onion neck rot: Effective management based on Achille’s heel. Invited presentation at the 62nd Annual Muck Vegetable Growers’ Conference, 3-4 Apr. 2013, Bradford, Ontario, Canada. Shock, C.C., E.B.G. Feibert, and J.M. Pinto. 2013. Review of two decades of progress in the development of successful drip irrigation for onions. International Irrigation Show, November 5-7, Austin, TX. 2. Research Reports: Abstracts and Papers at National Professional Meetings Arif, M., Armstrong, C.M., Knerr, A.J., Lupien, S., Dugan, F.M., Du Toit, L.J., & Schroeder, B.K. (2013). Modification of oligo design for enhanced sensitivity of a DNA macroarray for detection of fungal onion bulb rot pathogens. Phytopathology 103:S2.8 (Abstr.). National meeting of the American Phytopathological Society, 10-14 Aug. 2013, Austin, TX. Buckland, K., J. Reeve, D. Alston, C. Nischwitz, and D. Drost. 2013. Effects of Nitrogen Fertility and Crop Rotation on Onion Growth and Yield, Thrips Densities, and Iris Yellow Spot Virus, and Soil Properties. Agriculture, Ecosystems, and the Environment 177:63-74. Cramer, C.S. 2013. Breeding for resistance to Iris yellow spot. W2008: Biology and Management of Iris yellow spot virus (IYSV) Other Diseases, and Thrips in Onions. Annual Meeting. Denver, CO. December 12, 2013. Cramer, C.S. and N. Kamal. 2013. Measuring selection progress in onion germplasm after one selection cycle for reduced Iris yellow spot symptom expression. HortScience 48:S363. (Abstr.) Cramer, C.S. and N. Kamal. 2013. Selection progress for reduced Iris yellow spot symptom expression in onion germplasm after one selection cycle (p. 26). 2013 Joint Annual Meeting of the Plant Breeding Coordinating Committee and National Association of Plant Breeders. Tampa, FL. Drost, D., D. Alston, and C. Nischwitz. 2013. IYSV and Thrips Management-Utah. Annual Meeting, W2008 Working Group. Denver CO. Dec 12, 2013. Drost, D., D. Alston, and C. Nischwitz. 2013. Utah State Report. Annual Meeting, W2008 Working Group. Denver CO. Dec 12, 2013. Dugan, F. M., Lupien, S. L., Vahling-Armstrong, C. M., Chastagner, G. A., and Schroeder, B. K. 2013. Host range of Penicillium spp. (blue mold) rotting bulb crops. Phytopathology 103:S2.37 (Abstr.). National meeting of the American Phytopathological Society, 10-14 Aug. 2013, Austin, TX. Gourd, T., Hammon, R., Hammond, E., Moore, S., Schwartz, H., Sakata, R., and Petrocco, D. 2013. Economic and Biological Impact of Companion-Crop-Planted Onions to Non-Companion-Crop-Planted Onions. Galaxy Extension Conference, September 18, 2013. Pittsburgh, PA. Hardin, J., Cranshaw, W., and Szostek, S. 2013. Thrips associated with the environs of onion fields in Colorado. American Entomological Society Meeting Poster, Nov. 12, 2013. Hoepting, C.A., Nault, B. A., and S.V. Beer. 2013. Update on IYSV, Onion thrips and other diseases in New York. Annual Meeting for Multi-State Project W2008: Biology and Management of Iris yellow spot virus (IYSV), Thrips and Other Diseases in Onions. Denver, CO. Nault, B. A., and C. A. Hoepting. 2013. Onion thrips management in onion in New York. Annual Meeting for Multi-State Project W2008: Biology and Management of Iris yellow spot virus (IYSV), Thrips and Other Diseases in Onions. Denver, CO. Nault, B. A. and A. M. Shelton. 2013. It’s not all fruit in the Big Apple: Vegetable pest management of onion thrips in onion and cabbage. In PI-E Section Symposium: Current Status of Vegetable Insect Pests in the USA. Entomological Society of America Annual Meeting, November 13, 2013, Austin, TX. Pfeufer, E.E. and B.K. Gugino. 2013. Environmental factors and production practices associated with bacterial diseases of onion. 2013 Mid-Atlantic Fruit and Vegetable Convention Proceedings, PA Vegetable Growers Association, Richfield, PA. Pp. 171-174. Reitz, S.R. 2013. Lessons learned from a distant land: Onion thrips and their management in the Pacific Northwest. Symposium on Thrips – Small Players with Big Damages, Annual Meeting of Florida Entomological Society, Naples, FL, 17 July. Sharma-Poudyal, D., Paulitz, T., Porter, L., Eggers, J., Hamm, P.B., and du Toit, L.J. 2013. Rhizoctonia spp. dynamics and optimal timing of glyphosate application to cereal cover crops to manage onion stunting in Washington and Oregon. Oral presentation, national meeting of the American Phytopathological Society, 10-14 Aug. 2013, Austin, TX. Phytopathology 103:S221-O. (Abstr.) Shock, C.C., E.B.G. Feibert, L.D. Saunders. 2013. Onion variety response to plant population and irrigation system. Annual Conference of the American Society of Horticultural Science, Palm Desert, CA, 25 July. Shock, C.C., J.M. Pinto, H. Kreeft, R. Ross, T. Laubacher and B. Shock. 2013. E. coli and Onions. Treasure Valley Irrigation Conference, Four Rivers Cultural Center, Ontario, OR, 17 December. Shock, C.C. and B.M. Shock. 2013. Preliminary Results, E. coli and Onions. Multi-State Project, W2008: Biology and Management of Iris Yellow Spot Virus (IYSV), Other Diseases, and Thrips in Onions, Denver, CO, December 12. Singh, N. and C.S. Cramer. 2013. Selection progress for reduced Iris yellow spot symptom expression in onion. HortScience 48:S364. (Abstr.) Smith, E. A., E. J. Shields, M. Fuchs and B. A. Nault. 2013. Diurnal dispersal of onion thrips, Thrips tabaci (Lindeman), in an onion ecosystem. Entomological Society of America Annual Meeting. Austin, TX. November 11, 2013. Szostek, S. and Schwartz, H. F. 2013. Onion thrips (Thrips tabaci) and Iris yellow spot virus survival throughout Colorado winters. Phytopathology 103:142. American Phytopathological Society Meeting Poster, Aug. 12, 2013. Austin, TX. Uchanski, M.E. and C.S. Cramer. 2013. NM State Report. W2008: Biology and Management of Iris yellow spot virus (IYSV) Other Diseases, and Thrips in Onions. Annual Meeting. Denver, CO. December 12, 2013. Waters, T.D. 2013. Thrips Management in Onion. Pacific Northwest Insect Management Conference, Portland, OR. Waters, T.D., Pappu, H., Dutoit, L.J., Schroeder, B.K., & Wohleb, C.H. 2013. Update on IYSV and Thrips in Washington State. W2008, Denver, CO. Waters, T.D., & Walsh, D. 2013. Thrips Management in Onion in Washington State. W2008, Denver, CO. 3. Reports at Grower meetings and field days Alston, D. 2013. Activity of New Insecticide Modes-of-Action on Onion Thrips Life Stages. Utah Onion Association winter meeting, Brigham City, Utah. February 12, 2013. Alston, D. 2013. Landscape effects on onion thrips, IYSV and onions. Utah Onion Association winter Summer Field Tour. Brigham City, Utah. August 13, 2013. Alston, D., Nischwitz, C., and Drost, D. 2013. USU ipmPIPE Thrips/IYSV monitoring protocols and ipmPIPE and onion website information. Utah Onion Association Summer Field Tour. Brigham City, Utah. August 13, 2013. Asselin, J.-A., Bonasera, J., Hoepting, C., Zaid, A. and Beer. S. 2013. Update on bacterial disease management. Orange County Onion School. March 1, 2013. Middletown, NY. Baskett, J., Arif, M., Mavrodi D., Mavrodi O., and Schroeder B. K. Epifluorescence microscopy of temporal interactions of Enterobacter cloacae in onions. NSF REU Undergraduate Research Symposium, Washington State University, Pullman, WA, 2 August 2013. Beer, S. V., 2013. Bacterial disease incidence and control in onions. 2013 New York State Onion Industry Council. Winter Meeting. Cornell Cooperative Extension. Ithaca, NY. February 21, 2013. Bunn, B. and D. Alston. 2013. Influences of the Agricultural Landscape on Onion Thrips and IYSV. Utah Onion Association winter meeting, Brigham City, Utah. February 12, 2013. Cramer, C.S. Screening onion entries for tolerance/resistance to thrips and Iris yellow spot virus. NM Onion Field Day. Las Cruces, NM. July 16, 2013. Cramer, C.S. Breeding for resistance to Iris yellow spot. Pacific Northwest Vegetable Association Conference. Pasco, WA. November 13, 2013. Cramer, C.S. Breeding for resistance to Iris yellow spot in onion. Hazera Genetics and Nickerson-Zwaan Onion Research Teams Annual Meeting. Visalia, CA. July 30, 2013. Drost, D. 2013. Crop Rotations and Onion Productivity: Does Planting Date Really Matter. Utah Onion Association winter meeting, Brigham City, Utah. February 12, 2013. Drost, D. 2013. 2013 Onion Variety Trial. Utah Onion Association Summer Field Tour. Brigham City, Utah. August 13, 2013. du Toit, L.J. Disease management in onion seed crops: What? When? How? Columbia Basin Vegetable Seed Association Annual Meeting, 15 Jan. 2013, Moses Lake, WA. (~70 people) du Toit, L.J. Emerging onion diseases in the Columbia Basin. Columbia Basin Crop Consultants’ Association Short Course, 16-17 Jan. 2013, Moses Lake, WA (~120 people). du Toit, L.J. Mycorrhizae in onion bulb crops. Organic Session. Pacific Northwest Vegetable Association 26th Annual Conference & Trade Show, 13-14 Nov. 2013, Kennewick, WA. (~75 people) du Toit, L.J. Why was pink root so prevalent in 2013? Onion Session. Pacific Northwest Vegetable Association 26th Annual Conference & Trade Show, 13-14 Nov. 2013, Kennewick, WA. (~125 people) Gugino, B.K. Vegetable disease update for 2013. PVGA Vegetable Grower Field Day, Southeast Agricultural Research and Extension Center, Manheim, PA. August 6, 2013. Hoepting, C.A. 2013. Growing GIANT onions! And managing bacterial soft rot. Mohawk Valley Produce Auction Growers Meeting. Canajoharie, NY. December 5, 2013 (20 participants). Hoepting, C.A. 2013. Best management practices for onion pests. North Country Allium School. Plattsburg, NY. October 22, 2013 (34 participants). Hoepting, C.A. 2013. Best management practices for onion pests. North Country Allium School. Canton, NY. October 21, 2013 (25 participants). Hoepting, C.A. Role of adjuvants in development of bacterial disease. Annual Elba Muck Onion Twilight Meeting. Elba, NY. August 8, 2013 (36 participants). Hoepting, C.A. 2013. An IPM approach to managing bacterial diseases of onions. Bradford Muck Vegetable Conference. Bradford, Ontario, Canada. April 4, 2013 (70 participants). Hoepting, C.A. 2013. Small-scale onion pest and disease update. Chautauqua Produce Auction Meeting. Clymer, NY. March 15, 2013 (35 participants). Hoepting, C.A. 2013. Role of adjuvants in bacterial diseases of onions. NYS Onion Industry Annual Winter Meeting. Ithaca, NY. February 21, 2013 (12 participants). Hoepting, C.A. 2013. An IPM approach to managing bacterial diseases of onion. 2013 University of Wisconsin Extension and Wisconsin Potato and Vegetable Growers’ Association Grower Conference. Stevens Point, WI. February 6, 2013 (10 participants). Hoepting, C.A. and B.A. Nault. Onion insect management update. Annual Elba Muck Onion Twilight Meeting. Elba, NY. August 8, 2013 (36 participants). Hoepting, C.A and B.A. Nault. 2013. Winning the Battle: Controlling onion thrips in New York. Bradford Muck Vegetable Conference. Bradford, Ontario, Canada. April 4, 2013 (70 participants). Nischwitz, C. 2013. Update on IYSV – ELISA-positive Weeds and Post-harvest Storage Diseases. Utah Onion Association winter meeting. Brigham City, Utah. February 12, 2013. Nault, B. A. 2013. Integrated pest management of onion thrips. In Onion session. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA. January 30, 2013. Nault, B. A. 2013. Insect pests and management update. 2013 New York State Onion Industry Council Winter Meeting. Cornell Cooperative Extension. Ithaca, NY. February 21, 2013. Nault, B. A. 2013. Insect management for onions. Orange County Onion School. March 1, 2013. Middletown, NY. Nault, B. A. 2013. Managing onion insect pests. Oswego County Onion Twilight Meeting. Cornell Cooperative Extension of Oswego County. Oswego, NY. June 25, 2013. Nault, B. A. 2013. Update on new insecticides for vegetable insect pest management in New York. Cornell Cooperative Extension’s Agricultural In-Service Annual Meeting. November 21, 2013. Ithaca, NY. Pfeufer, E.E. Managing bacterial diseases of onion. Lancaster County Onion Co-op Meeting, Leola, PA. March 20, 2013. Pfeufer, E.E. Environmental factors and production practices associated with bacterial diseases of onion. 2013 Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA. January 28, 2013. Reitz, S.R. 2013. Onion thrips biology and management. Pacific Northwest Vegetable Association, Kennewick, WA, 13 November. Schwartz, H. F. 2013 Onion virus management and updates. Annual Education Meeting of the Colorado Onion Association on January 31, 2013 at Eaton, CO. Schwartz, H. F. 2013 Onion disease management and updates. Annual Education Meeting of the Utah Onion Association on February 12, 2013 at Brigham City, UT. Schwartz, H. F. 2013 Onion disease management and updates. Annual Education Meeting of the National Onion Association on July 18, 2013 at Loveland, CO. Shock, C.C. E.B.G. Feibert, and L.D. Saunders. 2013. Onion Variety Trial Report 2012. Idaho and Malheur County Onion Growers’ Associations – 53rd Annual Meeting, Four Rivers Cultural Center, Ontario, OR, 5 February. Shock, C.C. E.B.G. Feibert, and L.D. Saunders. 2013. Plant population options for marketing long-day onions. Idaho and Malheur County Onion Growers’ Associations – 53rd Annual Meeting, Four Rivers Cultural Center, Ontario, OR, 5 February. Shock, C.C. E.B.G. Feibert, L.D. Saunders, E. Jemmett, and S. Reitz. 2013. Alternative Methods for Thrips Control in Onions, 2012. Idaho and Malheur County Onion Growers’ Associations – 53rd Annual Meeting, Four Rivers Cultural Center, Ontario, OR, 5 February. Shock, C.C., S. Reitz, and E.B.G. Feibert. 2013. Onion production tour including thrips control, iris yellow spot virus, fertigation, fumigation, onions grown from sets and transplants, irrigation management and soil moisture monitoring. Summer Farm Festival and Field Day, Oregon State University Malheur Experiment Station, Ontario, OR, 10 July. Shock, C.C. 2013. Food and Drug Administration Tour of Onion Production, Ontario, OR, 12 August. Uchanski, M.E. Onion impPIPE project update; year 3. NM Onion Field Day. Las Cruces, NM. July 16, 2013. Udquim, K.-I. T., Arif, M., du Toit, L.J., and Schroeder, B.K. 2013. Detection and discrimination of Botrytis species, causal agents of onion bulb rot, using quantitative polymerase chain reaction (qPCR) melting curve analysis. The Summer 2013 Undergraduate Research Poster Symposium at Washington State University, The Office of Undergraduate Research, 2 Aug. 2013, Pullman, WA. Waters, T.D. 2013. Onion Insect Control. Walla Walla Farmers Co-Op Grower Meeting, Walla Walla, WA. Waters, T.D. 2013. Insect Control in Vegetables. Pesticide Recertification Day, Ontario, OR. Waters, T.D. 2013. Thrips Management in Onion. Pacific Northwest Vegetable Association, Kennewick, WA. Waters, T.D. 2013. Insect Control in Onion. Farm Fair, Hermiston, OR. Washington State University (WSU) Onion Cultivar Storage Demonstration Trial, L&L Farms, Othello, WA, 8 Feb. 2013. Evaluation of 55 onion cultivars (3 replicate plots of 55 bulbs evaluated/cultivar) for storage rots and storage quality. Organized by Tim Waters & Carrie Wohleb, WSU Extension Educators. Presentations were given to ~75 growers, consultants, breeders, regulators, extension educators, graduate students, postdoctorates, researchers, etc. at the 2013 Washington State University Onion Field Day, 29 August 2013, Hartley Farms, near Benton City, WA. The presentations covered materials included in the field day handouts, as listed above in the publications section. Internet Resources Hoepting, C.A. and S.V. Beer. 2013. Exploring the relationship between nitrogen, plant spacing and bacterial diseases of onion in New York: Reduced nitrogen and closer spacing could result in less rot. Cornell Vegetable Program website. http://rvpadmin.cce.cornell.edu/pdf/submission/pdf106_pdf.pdf Hoepting, C.A. and S.V. Beer. 2013. Role of adjuvants in bacterial diseases of onions. Cornell Vegetable Program website. http://rvpadmin.cce.cornell.edu/pdf/submission/pdf115_pdf.pdf Schwartz, H. F. 2013. Web site dedicated to information and resources on onion pest management and/or thrips and IYSV. http://www.alliumnet.com/index.htm Onion Disease Management strategies, reports and publications, including those on IYSV and thrips and other diseases. http://www.colostate.edu/Orgs/VegNet/vegnet/onions.html Onion ipmPIPE and Disease Diagnostics, including those on IYSV and thrips, in addition to other resources such as weather, forecasts, markets: http://apps.planalytics.com/aginsights/pipehome.jsp http://onion.coop/ Pacific Northwest Vegetable Extension Group (PNW VEG) website (http://mtvernon.wsu.edu/path_team/vegpath_team.htm) with sections on onion diseases, pests, and other problems, as well as IPM resources: e.g., http://mtvernon.wsu.edu/path_team/onion.htm and http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion Schwartz, H. F., and Gent, D. H. 2013. High Plains Integrated Pest Management Resource. On-line IPM bulletin with updated onion disease and pest reviews, and pesticide recommendations. http://wiki.bugwood.org/HPIPM%3AOnion Preliminary studies on Escherichia coli and onion can be found in the Oregon State University Agricultural Experiment Station website. http://www.cropinfo.net/crops/PrelininaryStudiesOnEcoliAndOnion_ExtCrS148_31Oct2013.pdf Shock, C.C., J.M. Pinto, T.A. Laubacher, R.D. Ross, A.C. Mahony, H. Kreeft, and B.M. Shock, 2013. Movement of Escherichia coli is soil as applied in irrigation water. In Shock, C.C. Ed. Preliminary studies on Escherichia coli and onion. Oregon State University Malheur Experiment Station, Department of Crop and Soil Science Special Report, Ext/CrS 148: 1-17. Shock, C.C., J.M. Pinto, T.A. Laubacher, R.D. Ross, A.C. Mahony, H. Kreeft, and B.M. Shock, 2013. Survival of Escherichia coli on onion during field curing and packout. In Shock, C.C. Ed. Preliminary studies on Escherichia coli and onion. Oregon State University Malheur Experiment Station, Department of Crop and Soil Science Special Report, Ext/CrS 148: 18-27. Shock, C.C., J.M. Pinto, H. Kreeft, and B.M. Shock, 2013. Onion storage in sterilized new plastic crates compared to storage in old wooden boxes. In Shock, C.C. Ed. Preliminary studies on Escherichia coli and onion. Oregon State University Malheur Experiment Station, Department of Crop and Soil Science Special Report, Ext/CrS 148: 28-35. Ross, R.D., C.C. Shock, T.A. Laubacher, J.M. Pinto, A.C. Mahony, H. Kreeft, and B.M. Shock, 2013. Simulated filtration pond to remove Escherichia coli from irrigation water. In Shock, C.C. Ed. Preliminary studies on Escherichia coli and onion. Oregon State University Malheur Experiment Station, Department of Crop and Soil Science Special Report, Ext/CrS 148: 36-43. Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2013. 2012 Onion variety trials. p 12-25 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144. http://www.cropinfo.net/AnnualReports/2012/20121OnionVar.php Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2013. Onion production from transplants and sets. p 26-34 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144. http://www.cropinfo.net/AnnualReports/2012/20122OnionTrans.php Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2013. Onion variety response to plant population and irrigation system. p 35-62 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144. http://www.cropinfo.net/AnnualReports/2012/20123OnionIrrig.php Shock, C.C., E.B.G. Feibert, K.J. Barlow, A.L. Rock, L.D. Saunders, E. Jemmett, and S. Reitz. 2013. Insecticide rotations for thrips control in onions, 2012. p 63-69 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144. http://www.cropinfo.net/AnnualReports/2012/20124OnionThrips.php Shock, C.C., E.B.G. Feibert, K.J. Barlow, A.L. Rock, L.D. Saunders, E. Jemmett, and S. Reitz. 2013. Alternative methods for thrips control in onions, 2012. p 70-75 In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2012, Department of Crop and Soil Science Ext/CrS 144. http://www.cropinfo.net/AnnualReports/2012/20125OnionThripsAlt.php Shock, C.C., F.X. Wang, R.J. Flock, E.B.G. Feibert, C.A. Shock, and A.B. Pereira. 2013. Irrigation monitoring using soil water tension. Sustainable Agriculture Techniques, Oregon State University Extension Service. EM 8900 10p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37569/em8900.pdf Shock, C.C. T. Welch, F.X. Wang R. Flock, E.B.G. Feibert, C.A. Shock, y A.B. Pereira. 2013. El control del riego mediante la tensión matricial del suelo. Tecnicas para la agricultura sostenible, Oregon State University Extension Service, Corvallis. EM 8900-S-E. 10p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37648/em8900-s.pdf Shock, C.C. 2013. Drip Irrigation: An Introduction. Sustainable Agriculture Techniques, Oregon State University Extension Service, Corvallis. EM 8782-E 8p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37461/em8782.pdf Shock C.C. y T. Welch. 2013. El riego por goteo: Una introducción. Tecnicas para la agricultura sostenible, Oregon State University Extension Service, Corvallis. EM 8782-S 9p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37462/em8782-S.pdf Shock, C.C., R.J. Flock, E.B.G. Feibert, C.A. Shock, and J. Klauzer. 2013. Drip irrigation guide for onion growers in the Treasure Valley. Sustainable Agriculture Techniques, Oregon State University Extension Service. EM 8901 8p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/43725/em8901.pdf Shock, C.C., B.M. Shock, and T. Welch. 2013. Strategies for efficient irrigation water use. Sustainable Agriculture Techniques, Oregon State University Extension Service. EM8783. 7p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/37465/em8783.pdf

Impact Statements

Outputs of this work posted on web sites and presented at various meetings will be used by the Colorado and national onion industries, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective management strategies including the promotion of varieties that are less susceptible to damage by thrips and the virus.
Germplasm was identified that possessed a reduced number of thrips per plant than most entries. Entries were identified that exhibited less severe IYS disease symptoms than most entries. Selection for reduced thrips number and IYS disease severity appears to be effective. Additional cycles of selection may be beneficial for increasing tolerance to thrips and/or IYS.
As a result of growers? using Cornell-recommended IPM program for thrips (combines spray thresholds, resistance management practices, proper adjuvants, avoiding non-compatible tank mixes with fungicides, and reduced nitrogen fertilizer inputs), effective management of onion thrips was achieved with 40 to 57% fewer insecticide applications per field compared with standard weekly spray program. Potentially, this translates into an average 50% reduction in annual insecticide use statewide and a savings of $1.1 million in insecticide costs, not including savings in fertilizer costs. Use of the Cornell-recommended IPM program for managing onion thrips reduced Environmental Impact Quotient (EIQ) points by a staggering 94% from 2005 when growers were unable to effectively control onion thrips with an arsenal of insecticides that were environmentally not friendly.
Results from our work were presented at various meetings throughout New York and beyond and will be used by the national onion industry, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective insect, virus and disease management strategies.
In Oregon, findings from this research has been posted on websites, published in newsletters, presented at various meetings, and communicated directly with growers and other industry personnel. This information has led to the adoption of more effective management programs in onion cropping systems in Oregon: 1). More growers are adopting onion varieties with greater tolerance to IYSV.
2). More growers are adopting drip irrigation and maintaining better management of soil moisture. The onions grown with drip irrigation and careful irrigation scheduling tended to have less severe problems with IYSV. 3). Growers continue to improve their use of insecticide rotation programs through the growing season. Research trials have led to the identification of effective season-long insecticide use programs. These programs have enabled growers to successfully manage thrips over a single growing season and reduce the risk of insecticide resistance developing.
4). Due to better knowledge of the transmission of IYSV, fewer growers are planting over-wintering onions. With fewer overwintering onions and better cull onion disposal, growers are breaking the natural green bridge keeping IYSV pressure high from one production year to the next. Some growers continued to suffer IYSV related yield losses due to over-wintering onion bulb or seed fields close to their summer production fields.
In Pennsylvania, an extensive data set on the potential factors associated with onion bacterial diseases has been collected and continued comprehensive analysis of this data set is further elucidating some of the factors most closely associated with onion bacterial diseases. In the meantime, growers are gaining a better understanding about what bacterial pathogens are causing losses at harvest and in storage and making changes in current production practices to reduce losses by modifying soil temperatures through use of alternative plastic mulches or physical manipulation of the plastic at bulbing.
Results of preliminary mycorrhizal survey work were presented at the 2013 WSU Onion Field Day, and published in the popular magazine ?Onion World? in Nov. 2013 (see publications listed below). Grower-cooperator trials in the Columbia Basin with mycorrhizal inoculations are planned for 2014, based on very promising preliminary results demonstrating that inoculation of soil with mycorrhizae can completely prevent expression of onion stunting symptoms caused by Rhizoctonia solani.
Similarly, an article on pink root of onion that focused on why pink root was so severe in 2013 in the Columbia Basin of central Washington and north-central Oregon was published in the Dec. 2013 issue of ?Onion World? (see below), based on a presentation given by Lindsey du Toit at the 2013 Pacific Northwest Vegetable Association Annual Convention & Trade Show in Nov. 2013. The article highlighted the biology and management of pink root.
More growers in Utah are using lower nitrogen levels (130-150 lb. N/A) and applying fewer insecticide sprays on onions. Growers report saving $150-200/A on reduced pesticide inputs and by using less N the savings on fertilizer costs is $75-100/A. Lower N use may also provide environmental benefits through less N leaching. We estimate that more than 450 acres of onions in Utah are now being grown using lower N level recommended by Utah State University.
Recent research conducted by Utah State University (2011-2013) continues to show that onions planted after corn in the crop rotational sequence have few thrips than when onions are grown after wheat. This may contribute to lower pesticide usage. In 2013, six growers used this system and approximately 250 acres were grown after corn. We started to monitor onion thrips pressure and study how crops grown adjacent to onion fields influences thrips migration patterns, IYSV and virus harboring plants. We evaluated 26 field sites from 10 growers. This data set is being analyzed and will be reported on in detail elsewhere.

Date of Annual Report: 03/06/2015

Report Information

Annual Meeting Dates: 01/01/2014 - 12/31/2014
Period the Report Covers: 01/01/2014 - 12/01/2014

Participants

Participants Attachment:

Attachment

Brief Summary of Minutes

Minutes Attachment:

Attachment

Accomplishments

Objective 1. Evaluate onion germplasm for greater levels of tolerance to Iris yellow spot virus (IYSV), other pathogens and thrips. Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – During 2014 the Colorado team confirmed that the following germplasm expressed significantly greater plant vigor after season-long exposure to thrips at Fort Collins; and include PI 264320, 264648, 288903, 546106, and 546192. These PIs have shown tolerance to thrips and IYSV in previous tests in Colorado; and have performed equal to or better than the cultivar Advantage. In 2013, several widely-grown onion varieties were evaluated for their total phenolic content. Samples were taken from University-sponsored trials conducted in northern Colorado, southern Colorado, and the Columbia Basin of central Washington. Samples encompassed popular yellow, white, and red-skinned varieties. Across the geographical locations, the yellow-skinned variety “Granero” had the highest total phenolic content and the white-skinned variety “Cometa” had the lowest content. Two onion cultivars, the yellow-skinned variety “Vaquero” and the red-skinned variety “Redwing” were evaluated in an anticancer assay by altering the diet of laboratory rodents. In an aggressive in vivo model for breast cancer, “Vaquero” had protective activity and “Redwing” had some, but significantly less activity. Georgia (R. Gitaitis, B. Dutta, and B. Srinivasan) – No efforts have been made in this area in Georgia as our annual germplasm trial is conducted using short day onions that are grown throughout the fall and winter. In general temperatures are too low for expression of IYSV thus ratings typically cannot be made. New Mexico (C. Cramer) – Sixty-nine onion breeding lines selected for reduced Iris yellow spot (IYS) disease symptom expression, 7 plant introduction (PI) accessions from the U.S. germplasm collection, 7 experimental breeding lines from the New Mexico State University (NMSU) breeding program, and 2 commercial cultivars were evaluated for the number of thrips per plant and IYS disease symptoms. Fourteen selected lines exhibited a lower IYS disease incidence than ‘Rumba’ at 13 weeks after transplanting. At 16 weeks, six selected lines exhibited a lower disease incidence than their parental line, NMSU 07-53-1. Five selections of different lines were made this year from this material. Seeds of 72 different lines were produced in this year. New York (B. Nault, S. Beer and C. Hoepting) – A combination of a thrips-resistant cultivar (cv. ‘Advantage’) and insecticide applications timed using action thresholds was evaluated in a commercial onion field in 2014. The onion thrips infestation occurred later in the season and was lower than typical. Thrips were controlled effectively in small-field plots of ‘Advantage’ and in the thrips-susceptible cultivar, ‘Santana’, following either a weekly insecticide spray program or an action threshold program. However, fewer insecticide applications were applied in the action threshold program compared with the weekly spray program, especially for ‘Advantage’. Season total densities of onion thrips in untreated plots were similar between ‘Advantage’ and the ‘Santana’. Despite the similar densities of thrips in the two cultivars, damage levels were much lower in ‘Advantage’ than in ‘Santana’. The reason for this difference is not understood, but may be explained by differences where thrips feed on the two cultivars and/or the larger canopy of ‘Advantage’ compared with ‘Santana’, which would result in a smaller proportion of the ‘Advantage’ canopy being damaged by thrips. Marketable bulb yield for ‘Advantage’ was similar between the insecticide treatments and untreated control, indicating that the low levels of thrips damage to ‘Advantage’ was not enough to reduce bulb yields. Unlike previous years, marketable yield of ‘Santana’ in untreated plots also did not differ from insecticide-treated plots; thrips damage occurred very late in the season and apparently did not reduce bulb yield. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) – Early maturity and full season onion variety trials were conducted in 2014 with support of Idaho-Eastern Oregon Onion Committee and various seed companies. The full season varieties were grown under both furrow and drip irrigation. All varieties were evaluated for their yield, maturity and susceptibility to thrips damage and IYSV. Varieties had significant differences in IYSV in 2014. Utah (D. Drost) - Thirty-six commercially available Spanish onion cultivars from seven companies were assessed for growth, productivity, maturity and rated for IYSV. Symptom expression of IYSV in 2014 was low; however, all varieties evaluated showed visual evidence of IYSV under field conditions. IYSV did not appear to impact bulb yield. Further evaluation of materials will occur in late January 2015 to assess rots and weight losses in storage. Work on correlations between IYSV incidence and storage losses needs additional evaluation when resources become available. Findings will be posted on USU website and preliminary findings were distributed to local growers and industry representatives in late December 2014. Objective 2. Investigate thrips biology and IYSV epidemiology to improve management strategies. Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – There is no evidence that IYSV is seed transmitted. Onion seed included in double antibody sandwich enzyme linked immunosorbent assays (DAS-ELISA) to detect IYSV occasionally yielded a positive result. IYSV was detected in the pedicels, petals, anthers, and fruits of onion flowers by reverse transcriptase polymerase chain reaction (RT-PCR). Onion seed collected from several cultivars of IYSV symptomatic plants was grown out under greenhouse and growth chamber conditions. IYSV was not detected in the six week old seedlings. Further investigation of onion seeds revealed IYSV could be detected in the seed coat, but not the emerging radicle. It is highly unlikely that IYSV can pass from the seed coat to the new plant during germination, and seeds remain an unlikely source of IYSV inoculum. IYSV distribution throughout onion leaves is uneven and patchy. A reverse transcription quantitative real time PCR was developed to compare relative amounts of IYSV within leaves and between cultivars. The amount of IYSV was greatest at the lesion site itself and decreased as distance from the lesion increased. No statistically significant differences were found in the amount of IYSV between susceptible cultivar Granero and tolerant cultivar Advantage. Georgia (R. Gitaitis, B. Dutta, and B. Srinivasan) – It was shown previously that tobacco thrips, Frankliniella fusca, could transmit Pantoea ananatis, causal agent of center rot of onion. Further investigations on the transmission of Pantoea agglomerans and Pantoea ananatis, both part of a group of organisms that cause the center rot complex, were conducted using onion thrips, Thrips tabaci, as the vector. This species of thrips acquired either bacterium in a similar manner. A small proportion of thrips (15-20%) acquired the bacteria after 1 hr of feeding and nearly 100% of the thrips acquired the bacteria after 48 hr of feeding. Additional experiments demonstrated that the bacteria could pass through the different developmental stages of thrips, including the pupal phase. Using fluorescent-labelled antibodies, we demonstrated that the bacteria remain localized in the thrips' gut and was not detected elsewhere in thrips' bodies and most importantly was not detected in the salivary glands or mouth. After feeding and acquisition, thrips' saliva and feces were collected and inoculated onto healthy onion seedlings. No transmission was observed with any of the saliva samples but transmission did occur with just using feces. It was speculated that the mode of transmission was contamination of feeding and other wounds via thrips' feces. Finally, it was demonstrated that if thrips were continually provided with a clean food source, their gut could be flushed clean of the contaminating bacteria within 5 days. New York (B. Nault, S. Beer and C. Hoepting) – During a week-long examination of thrips flight activity in August, we observed thrips dispersal occurring when temperatures were relatively warm (upper 70s) either at crepuscular morning or evening. Onion thrips populations collected from onion fields early in the season were genetically similar to those late in the season, suggesting that little mixing occurs from populations outside of onion. Additionally, the genetic population structure of onion thrips populations collected from onion and potato were completely different, despite the proximity of these crops to each other. Co-applications of insecticides (Agri-Mek, Movento and Radiant) with a non-ionic surfactant (Induce), a methylated seed oil (MSO), and mineral oils (PureSpray Green and JMS Stylet oil) were more effective for managing onion thrips than when these insecticides were used alone. Season-long management of onion thrips continues to be most effective using a series of products beginning with Movento (2 applications) followed by Agri-Mek (2 applications), and then Radiant (2 applications). The position of Exirel was examined in the middle and end of the sequence and both performed as well as the standard sequence shown above. An attempt was made to examine IYSV prevalence near potential sources for this virus: transplanted onion fields, weedy areas adjacent to onion fields, and onion cull piles (direct-seeded onion fields was the negative control). Lisianthus sp. was used as an indicator plant and these potted-plants were placed near these potential sources (n=5 locations per source; 20 plants per location). Lisianthus sp. plants were placed at sources for one week and then moved to a greenhouse for an additional week before determining whether it was infected with IYSV (June-Sept). No symptoms developed on plants and only a few tested positive for IYSV over the entire season. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) – Two insecticide rotation trials were conducted to evaluate the effectiveness of various insecticides in managing thrips and IYSV. One trial included all foliar applied treatments and the other featured insecticides applied through drip irrigation and by ground. Thrips populations and onion bulb yield varied significantly between treatments, suggesting that thrips and IYSV are significant limiting factors for onion production. Movento and Agri-mek were effective in early season thrips management. The timing of Movento applications is critical so that sufficient levels are in the plant before large thrips populations have developed. Radiant remains the most effective insecticide for mid to late season thrips management. Other materials (e.g., Aza-direct and M-Pede tank mixes) do not always reduce thrips abundance but do contribute to higher yields. Drip applied products did not outperform foliar applied products, but these applications may reduce grower expenses but reducing overall application costs. Insecticide susceptibility trials were conducted by collecting onion thrips from commercial fields throughout the area and exposing them to one of four commonly used insecticides (Agri-mek, Lannate, Movento, Radiant), and demonstrate that populations remain susceptible to these chemicals. Utah (D. Alston, D. Drost and C. Nischwitz) - Thirty one (31) field sites surveyed in 2014 in the onion production areas of Davis, Weber, and Box Elder Counties, Utah. Fields were evaluated from June until September for thrips, other insects, and IYSV. Soils sampled and plant growth determined. Field productivity measured and details on production practices gathered from growers. Crop rotations (alfalfa, corn, wheat) and nitrogen management (lo-hi N) influences on onion growth and productivity, onion thrips pressure and IYSV incidence evaluated in research trials during 2014. Finding show that onions grown with reduced N had fewer thrips than when grown at average grower applied N levels. Onion growth (leaf number, weight, and yield) was not influence by nitrogen. IYSV was found in all treatments. Research will continue through 2017. Washington (H. R. Pappu, T. Waters, C. Wohleb, and L. J. du Toit) - Field plots of onion (var. ‘Sabroso’ Bayer Vegetable CropScience, Parma, ID) were established at the WSU Research Farm in Pasco, WA and grown using drip irrigation and standard grower practices for agronomic and pest management inputs excluding thrips treatments. Plots were established in a random complete block design with four replications. In each instance, plots were 7.5 feet wide and 30 feet long. Applications (except where specified) were made with a CO2 pressurized back pack sprayer applying 30 gallons of water carrier per acre at 35 psi. Efficacy was evaluated four or five days after applications by counting the number immature and adult thrips per plant on 10 individual plants per plot in the field. All data for each sample date were analyzed by ANOVA and treatments means were compared to thrips population means from non-treated control plots in pairwise t-tests. At the end of the growing season onion yield and size were evaluated for comparison among treatments. Trials were conducted to determine insecticide efficacy and determine the treatment threshold for thrips on onions in Washington. A global genetic analysis of known IYSV nucleocapsid gene (N gene) sequences was carried out to determine the comparative population structure, spatial and temporal dynamics with reference to its genetic diversity and evolution. A total of 98 complete N gene sequences available in GenBank and reported from 23 countries were characterized by in silico RFLP analysis. Based on RFLP, 94% of the isolates could be grouped into NL or BR types while the rest belonged to neither group. The relative proportion of NL and BR types was 46% and 48%, respectively. A temporal shift in the IYSV genotypes with a greater incremental incidence of IYSVBR was found over IYSVNL before 2005 compared to after 2005. The virus population had at least one evolutionarily significant recombination event, involving IYSVBR and IYSVNL. Genetic differentiation studies showed inherent differentiation and infrequent gene flow between IYSVBR and IYSVNL genotypes corroborating the geographical confinement of these genotypes. Taken together the study suggests that the observed diversity in IYSV population and temporal shift in IYSVBR genotype is attributable to genetic recombination, abundance of purifying selection, insignificant positive selection and population expansion. Objective 3. Investigate the biology, ecology and epidemiology of other pathogens to improve management strategies. Colorado (H. Schwartz, S. Szostek, W. Cranshaw, M. Bartolo, T. Gourd, B. Hammon) – Disease incidence of Pink Root was too light to separate out effects of any treatment with Quadris or Serenade. There were no effects of treatments on leaf number, plant weight or root weight measurements 60 days after planting. Xanthomonas leaf blight infection (incidence and severity) was reduced by timely applications of bactericides such as Kocide 3000, Badge and experimentals when compared to the untreated control which sustained 40 percent canopy damage by the end of the season. A field trial comparison of Fusarium oxysporum tolerance among forty onion varieties under field growing conditions was located in Brighton, Colorado.This field has a long history of Fusarium issues. The soil type was a sandy loam. Onions were last planted in this field in 2008, followed by field corn in 2009, cabbage in 2010, sweet corn in 2011, field corn in 2012, and cabbage in 2013. Forty onion varieties were planted in a randomized complete block with four replicates. Onion varieties showed significant differences in infection rates and overall plant health during the growing season. Final yield analysis of all 40 onion varieties showed significant differences among varieties, but the differences could not be solely attributed to Fusarium infection. This study also showed that visual infection assessments of Fusarium basal rot did not always give a clear picture of how market yield could be impacted under high disease pressure. One onion variety had a high Fusarium infection rate based on visual symptoms yet produced a higher yield, possibly indicating a higher tolerance to Fusarium. Georgia (R. Gitaitis, B. Dutta, and B. Srinivasan) – Management strategies for sour skin were studied. In particular predictive models using concentrations of the cations of copper, iron, manganese and zinc were correlated with sour skin severity. It was speculated that the cations are affecting superoxide dismutase enzymes which in turn detoxify reactive oxygen species. This begins a cascade of reactions resulting in the production of salicylic acid and up-regulation of NPR1 gene leading to systemic acquired resistance products. The predictive models may have use in identifying fields of potentially high risk for sour skin. In time, it is hoped that prescribed fertility "cocktails" could be formulated and applied to onions in the field to enhance innate resistance mechanisms. Idaho (B. Shroeder) - The development of the DNA macroarray for the detection of onion bulb rots specifically applies to W2008: 1) Develop a DNA macroarray for detecting and differentiating pathogens that can cause onion bulb rots in storage: It became clear quite early in the project that the DNA macroarray could not encompass both the fungal and the bacterial pathogens in a single test. Therefore the development of a fungal DNA macroarray to detect 14 fungi and a bacterial DNA macroarray to detect 12 bacteria capable of causing onion bulb rot will be discussed below. A DNA macroarray was developed to detect the onion bulb rot fungi, Aspergillus niger, Botrytis aclada, Botrytis allii, Botrytis byssoidea, Botrytis cinerea, Fusarium oxysporum, Fusarium proliferatum, Kluyveromyces marxianus var. marxianus as well as several species of Penicillium. Efforts have focused on optimizing the detection conditions to eliminate cross reaction among the target bacteria listed above as well as non-target organisms associated with onion bulbs. Currently, there is some cross reaction among the Pseudomonas strains on the bacterial DNA macroarray. It is not clear why this is occurring and it is being investigated. The sensitivity of the bacterial DNA macroarray has not been determined. 2) Evaluate and optimize the DNA macroarray for testing onion bulbs: The fungal DNA macroarray was able to detect the presence of fungal pathogens present in non-symptomatic onion bulbs, suggesting that it could be used to predict the risk of storage rots. It has not been determined if the bacterial DNA macroarray can detect bacterial plant pathogens present in non-symptomatic onion bulbs as latent infections. A manuscript describing this work is in preparation. New York (B. Nault, S. Beer and C. Hoepting) – Bacterial Diseases of Onion Progress was made in developing techniques to accurately and efficiently identify bacterial pathogens. Two approaches were addressed. In the first, the diversity among bacteria in the nucleotide sequence of the gyraseB gene was utilized to identify bacterial pathogens. This approach was fully described in a recent publication (J. Microbiological Techniques (2014) 103: 1387-143. In the second, pairs of highly specific primers for use in PCR were designed to produce amplicons useful for the identification of Pantoea ananatis, Burkholderia species and Enterobacter cloacae, the three major pathogens of onion in New York State. This approach has been thoroughly tested and a publication describing the technique is currently in draft form. We anticipate submitting it for publication in the coming months. A new approach to define the etiology of disease development by the three important bacterial pathogens of onion in New York was conceived and implemented on a trial basis during the 2014 growing season. The goals are to determine when during the growing season onions become infested and infected by the three bacteria and when they are susceptible to infection by artificial inoculation. The point of this approach is to provide specific bases to thwart the development of disease at the most opportune times during the growing season. OxiDate®, a pesticidal product of Biosafe Systems LLC, that is registered for use against bacterial diseases on onions in New York was evaluated in collaboration with a New York grower. Replicates stripes of onion plantings were sprayed with OxiDate® in a tank mix of fungicides and insecticides every week or 10 days beginning in late June until a few weeks before harvest in September. Strips in the same field were treated similarly except they were not sprayed with OxiDate® . The hypothesis was that the material would reduce the populations of Enterobacter cloacae sufficiently to reduce rot caused by the pathogen, which is harbored in the soil in which the onions are grown. No substantial differences were found in the population of Enterobacter cloacae in the strips treated with OxiDate® and those not treated with OxiDate® Fungal Diseases of Onion Stemphylium leaf blight (SLB) emerged as a very serious leaf disease of onion in New York during the 2012-2013 growing seasons. Although it is not understood why this endemic disease of onion has moved from its usual backseat position as a secondary pathogen into the front seat as an aggressive pathogen, it appears that SLB is now a serious contender in the onion leaf disease complex in New York. Starting in July, SLB lesions form on the oldest leaves and leaf dieback progresses quickly often resulting in the onions “dying standing up” before they are fully mature. When onions die standing up the neck tissue does not seal and the bulbs tend to be of poorer quality. Downy mildew (DM) is a sporadic disease of onion in New York, which is favored by cooler temperatures and long periods of dew, and typically does not occur until late August. When it occurs in July, it has plenty of time to progress and spread causing excessive leaf dieback and the onions to die standing up. Occurrence of DM in July has increased in recent years. In general, in commercial onion production in New York, SLB pressure was lower in 2014 than it had been in the previous years. Although growers adjusted their fungicide programs to include fungicides with good activity against SLB, the relatively stress-free growing conditions likely played a role in preventing SLB from getting a good foothold. Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) – The United States Food and Drug Administration (FDA) has proposed draft rules to implement the Food Safety Modernization Act (FSMA). As part of FSMA, the FDA has proposed that plastic totes be substituted for wooden bins for the storage of onion bulbs as a means to reduce the risk of contamination of onions with potential human pathogens. The project started as a way to address the Food safety Modernization Act (FSMA) agricultural water quality rules. The FDA published proposed revisions to the rules at the end of September 2014. Because we will not know what the final rules are until late in 2015, we felt it was important to continue with research on ways to reduce E. coli levels in case that would be needed under the final rules. Although the final FSMA rules have not been published, we wished to determine if certain crop management and maintenance methods growers already use could be adapted for managing E. coli. The three different options for managing E. coli that we examined were: 1) Chlorine dioxide in drip irrigation systems. Injections of chlorine dioxide are used to control the growth of algae in drip irrigation lines. We found that current rates of chlorine dioxide virtually eliminate E. coli. Lower rates also significantly reduce E. coli levels far below proposed FDA standards of 126 CFU / 100 ml. 2) Copper Sulfate added to irrigation ditches. Copper sulfate can also be used to help control algae growing in irrigation ditches. We found that copper sulfate almost completely eliminates E. coli (we measured E. coli at several points along the irrigation ditch and at the end of furrows in a field). 3) Copper based fungicides and bactericides are used to manage onion diseases and improve onion storage quality. We examined the use of a late season application of a copper based fungicide to treat E. coli that may be on the onion bulbs in the field. We could not judge the effectiveness of this treatment because onions had no E. coli before the treatment was made, suggesting that onions are not likely to acquire E. coli. Pennsylvania (B. Gugino) – During the past 5 to 10 years, bacterial bulb decay, caused by a number of different bacterial pathogens, has assumed much greater importance in the Northeast region. In PA and NY, annual losses range from 5 to 40%. However, these losses are variable, between fields and within the same field; in many cases the full extent of disease losses is not evident until harvest or after post-harvest storage. In part this is because bacterial bulb decay often affects only a single internal scale while outer scales remain firm, such infected bulbs are virtually impossible to detect. Such onions are shipped and consequently rejected, which often results in entire loads being dumped, despite only a small percentage of bulbs being infected. In order to develop an integrated pest management plan it is important to understand what factors are associated with increased bacterial disease. One key factor is identifying where the bacterial pathogens are coming from (transplants, weeds, soil, etc.) so that management efforts can be directed towards excluding or reducing the pathogen from the field. The analysis of data collected from a large scale on-farm replicated plot survey conducted in 2011 and 2012 was completed in 2014 as part of a PhD dissertation in Plant Pathology by Emily Pfeufer. Results from this research have demonstrated that in PA, transplants and weeds can be potential sources of bacterial pathogen inoculum. In PA, the predominant bacterial pathogens were Pectobacterium carotovorum subsp. carotovorum, Pantoea agglomerans, and Pseudomonas marginalis pv. marginalis. In NY, Burkholderia cepacia was most commonly identified from symptomatic bulbs at harvest, followed by Enterobacter cloacae and Pantoea ananatis. Transplants and weeds were not surveyed for bacteria pathogenic to onion in NY. However, B. cepacia was identified in 83% of the soil samples collected in the NY survey. Texas (O. Alabi) – During the 2013/2014 cropping season, a total of 25 onion fields spread across the Lower Rio Grande Valley (LRGV) of South Texas were surveyed for foliar pathogens of onions. At each location, overall visual assessment of disease was determined and four representative plants selected across the field for more detailed assessment and laboratory analysis. Pink root (Phoma terrestris) and stemphylium leaf blight (Stemphylium vesicarium) were recorded in 100 and 96 plants, respectively from all 25 fields indicating that both were the most predominant diseases of onions during the 2013/2014 growing season in the LRGV. They were followed by downy mildew (Peronospora destructor) in 38 plants from 13 fields, gray mold (Botrytis spp.) in 37 plants from 17 fields, purple blotch (Alternaria porri) in 30 plants from 14 fields, powdery mildew (Leveillula taurica) in 22 plants from 10 fields and iris yellow spot disease (Iris yellow spot virus) in 15 plants from 7 fields. Given that favorable environmental conditions for these diseases exist in the LRGV at different times during the onion growing season, the results point to the need for an integrated management strategy that takes into account avoidance of inoculum sources and timely applications of recommended fungicides to reduce initial infection and secondary development by fungal pathogens. Objective 4. Facilitate interaction and information transfer between W2008 participants, the onion industry and other stakeholders. Georgia (R. Gitaitis, B. Dutta, and B. Srinivasan) – The information in categories 2 & 3 was presented at the National Alliums Research Conference in Scottsdale, AZ in December, 2014. It also has been presented to the Vidalia Onion Growers at their annual spring field day. And finally, the information on transmission Pantoea spp. by thrips has been published in a peer review journal (Phytopathology 104:812-819). Oregon (S. Reitz, C. Shock, E. Feibert, and M. Saunders) – The Oregon project has continued to effectively transfer information pertinent to IYSV and thrips biology to growers, other onion industry parties, and the public through numerous meetings, field days, workshops, publications, and the internet. Results have been effectively communicated by grower and fieldman participation in the project planning and evaluation of results, field days for growers July 9, 2014 and August 26, 2014, an irrigation workshops on December 18, 2014, a pesticide short course, grower meetings on February 4, 2014, internet web sites (cropinfo.net), and results being reported in Onion World and other industry publications, such as the Capital Press. Pennsylvania (B. Gugino) – In Pennsylvania the research results were disseminated at several vegetable grower meetings/conferences including the Lancaster Onion Co-op meeting. On a national level, results were presented at the 2014 National American Phytopathological Society Meeting in Minneapolis, MN as part of a symposium titled “A Systems Approach for Microbe Management: From Food Safety to Plant Health” as well as a poster titled “Visual rating of bacterial disease severity as a threshold to time sweet onion harvest. In addition, Ph.D. candidate Emily E. Pfeufer, presented this research at Ohio State as part of the graduate student seminar exchange program. Results were also disseminated throughout the season through one-on-one with the growers collaborating in the intensive field survey project. We continued to disseminate the Diagnostic Pocket Series as well as the Onion Health Management and Production bulletin to interested growers and other stakeholders. Utah (D. Alston, D. Drost and C. Nischwitz) – Utah onion growers participated with Utah State University researchers and allowed them to survey 31 field sites (12 grower farms) in the Davis, Weber, and Box Elder County production onion areas in 2014. Fields were evaluated from early June through September for thrips, other insects, IYSV, plant growth and productivity. Variety research provided to and discussed with Utah growers (48 attendees) at the February 2014 winter onion meetings. USU research on weeds, crop rotations, crop nutrition, and IYSV provided to local growers as well (see presentations list below). Growers (38) attending the summer onion field tour (Aug 2014) learned about sustainable onion production, farm-scale thrips sampling and weed hosts, crop rotations and pest management, and onion varieties. Utah Onion Association board met twice (Apr, Nov) where they were provided with national updates on a variety of activities as well as information specifically needed by the local industry. Drost was an invited speaker at the NOA’s summer meetings where he outlined research and outreach efforts going on in Utah and how these can be applied to other production areas in the US. Details of Utah’s research presented in talks (Nischwitz) or poster (Drost et al) at the Dec NOA/NARC meetings in Phoenix, AZ. Washington (H. R. Pappu, T. Waters, C. Wohleb, and L. J. du Toit) - An onion pink root trial was completed near Connell, WA in a certified organic onion bulb crop to evaluate the potential for Serenade Soil to reduce the impact of this disease. The trial was carried out in both the south half and the north half of the field (repeats of the trial). The north half of the field had been rotated out of onions for only 2 years, and the south half for 4 years. As a result, pink root was much more severe in the north half of the field (average 66% of the roots with pink root symptoms/bulb) compared to the south half (an average 42% of the roots had pink root symptoms/bulb). A single application (banded over the bed) of Serenade Soil at planting at 4 qt/acre, or three applications at 2 qt/acre (at planting, 3 weeks and 6 weeks after planting) using a CO2-pressurized backpack sprayer, followed by 3-4 applications of water with the same applicator to incorporate the product into the soil, did not affect severity of pink root compared to the control plots. The results were similar for a trial completed in 2013 near Pasco, WA in a conventional onion bulb crop using this trial protocol. The trials indicate Serenade Soil may not reduce the impact of pink root in onion bulb crops, at least if applied as done in these trials. Symbiotic arbuscular mycorrhizal fungi (AMF) colonize roots of many plant species and help the plants mine soils for immobile nutrients, particularly phosphorus (P). AMF can also help defend plants against some root pathogens. Onions depend significantly on AMF since the symbiotic association compensates for the relatively sparse, unbranched roots with few root hairs. However, widespread use of soil fumigation and high rates of P fertilizer applications in onion crops in the Columbia Basin may negate or reduce significantly this symbiotic association with AMF. The inoculation protocol will need to be modified to facilitate detection of potential suppressive effects of AMF on pink root. Onion fungicide seed treatments commonly used in conventional onion crops in the Basin (Apron + Thiram, Farmore D300, and Farmore I500) all negated the beneficial effect of AMF on onion growth in growth chamber trials (including the repeated trial). However, soil application of the fungicide Quadris was either partially inhibitory (in one trial) or not inhibitory to AMF (in the repeat trial), and soil application of the fungicide Fontelis did not inhibit AMF (in either trial). These results have important ramifications for growers who routinely use fungicide seed and/or soil treatments for control of soilborne onion diseases. Attempts to evaluate AMF products in 3 grower-cooperator field trials in 2014 were complicated by incompatibility issues with product formulations and growers’ planting equipment. One or two AMF products were evaluated in each of three growers’ fields, but difficulties with application did not result in a reasonable evaluation of the potential value of these AMF inoculants in onion bulb crops. Additional research is needed to address these issues in order to obtain effective, robust evaluation of the potential value and cost-benefit of onion growers in the Columbia Basin using AMF products.

Publications

Publications Attachment:

Attachment

Impact Statements

Outputs of this work posted on web sites and presented at various meetings will be used by the Colorado and national onion industries, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective management strategies including the promotion of varieties that are less susceptible to damage by thrips and the virus.
In Georgia, it is a bit too early to assess the impact that this research might have on reducing either center rot or sour skin as management strategies based on the research have not yet been implemented to the point that we have made any recommendations.
In New Mexico, germplasm was identified that possessed a reduced number of thrips per plant than most entries. Entries were identified that exhibited less severe IYS disease symptoms than most entries. Selection for reduced thrips number and IYS disease severity appears to be effective. Additional cycles of selection may be beneficial for increasing tolerance to thrips and/or IYS.
As a result of growers? using Cornell-recommended IPM program for thrips (combines spray thresholds, resistance management practices, proper adjuvants, avoiding non-compatible tank mixes with fungicides, and reduced nitrogen fertilizer inputs), effective management of onion thrips was achieved with 80 to 75% fewer insecticide applications per field compared with standard weekly spray program. Potentially, this translates into an average of 265 to 300 dollars per acre in insecticide costs, not including savings in fertilizer costs. Results from our work were presented at various meetings throughout New York and beyond and will be used by the national onion industry, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective insect, virus and disease management strategies.
In Pennsylvania, an extensive data set on the potential factors associated with onion bacterial diseases has been collected and continued comprehensive analysis of this data set is further elucidating some of the factors most closely associated with onion bacterial diseases. In the meantime, growers are gaining a better understanding about what bacterial pathogens are causing losses at harvest and in storage and making changes in current production practices to reduce losses by modifying soil temperatures through use of alternative plastic mulches or physical manipulation of the plastic at bulbing.
In Washington, results from the thrips insecticide efficacy results were shared at the WSU Onion Field Day on August 28, 2014 and by a written report sent to onion producers. These results were also shared during various presentations at grower meetings and by individual consultations with growers to improve their insect management programs on their farms. Using the most effective insecticides will improve their yields and reduce the incidence of IYSV.

Date of Annual Report: 11/11/1111

Report Information

Annual Meeting Dates: 12/10/2015 - 12/10/2015
Period the Report Covers: 10/01/2014 - 09/30/2015

Participants

Steve Loring, NMSU-AES, sloring@nmsu.edu
Mark Uchanski, NMSU/CSU, uchanski@nmsu.edu; mark.uchanski@colostate.edu
Lindsey du Toit, WSU, dutoit@wsu.edu
Kenny McFarland, Utah onion grower, kennymcfarlandfarms@gmail.com
Hanu Pappu, WSU Pullman, hrp@wsu.edu
Robert Ehn, CA Garlic and Onion Res. Bd, robertehn@sbcglobal.net
Steve Beer, Cornell University, svb1@cornell.edu
Diane Alston, USU, diane.alston@usu.edu
Christy Hoepting, Cornell University, cah59@cornell.edu
Sarah Pethybridge, Cornell University, sjp277@cornell.edu
Brian Nault, Cornell University, ban6@cornell.edu
Bill Dean, River Point Farms, bill.dean@riverpointfarms.com
Kerrick Bauman, L&L Ag Production (WA), kerrick@llfarms.com
David Whitwood, Crookham Company, davew@crookham.com
Ron Gitaitis, University of Georgia, dronion@uga.edu
Claudia Nischwitz, Utah State University, claudia.nischwitz@usu.edu
Tim Waters, WSU, twaters@wsu.edu
Clint Shock, OSU, clinton.shock@oregonstate.edu
Juan C. Brevis, Bayer Vegetable Seeds, juan.brevis@bayer.com
Morgan Reeder, Grower, mlreeder@yahoo.com
Curtis L. Marble, Grower, clmarblefarms@gmail.com
Lisa Marble, Grower, lisasmarble@gmail.com
Dan Drost, USU, dan.drost@usu.edu

Brief Summary of Minutes

Call to Order, Welcome, Business of the Day, Thank You

The meeting was called to order by Dan Drost, Utah State University, who organized the meeting. Dan welcomed everyone to the meeting, and thanked the sponsors of the meeting – Utah Onion Association, Western SARE, National Onion Association, and the Pacific Northwest Vegetable Association.

New W2008 Administrator and Working Group Update

Steve Loring was introduced as the new Administrative Advisor to W2008. He is based at New Mexico State University. Steve noted that this group needs to prepare our annual report within 30 days of this meeting (Jan. 10, 2016).

W2008 meeting with the National Onion Association (NOA) and National Allium Research Conference (NARC)

The next W2008 meeting will take place in conjunction with the NOA/NARC meeting in Savannah, GA on Nov. 30-Dec. 3, 2016. Appreciation was expressed to Ron Gitaitis for agreeing to organize the NARC meeting.

Oral State Reports:

California (given by Bob Ehn):

Production: Yields are down from 0.5 to 1.0 ton per acre in both onions and garlic. Because of the drought, growers were forced to rely upon ground water to supplement the minimal surface water allocations. As the season progressed, salt content in ground water increased with much higher levels of selenium and boron. Boron toxicity was evident in several onion fields in the Central Valley. The warm winter of 2014/2015, with reduced chilling hours/lack of cold exposure on the fall planted garlic, caused reduced bulb size. Some brooming (vegetative growth from developing cloves) was observed. Thunderstorms in late May in the Central Valley damaged some harvested onions, and garlic that were dug and windrowed experienced staining that forced fresh market fields to be rendered to dehydrators.

Pests/diseases: Thrips populations were low throughout the year in the desert, Central Valley, and northern Tulelake areas. There were reports of IYSV in the desert areas of southern California. Infected onion transplants in a nearby field that were being grown for seed seem to have been the origin of the virus, with surrounding dehydrator onion fields showing IYS symptoms on fields near the onion transplants. Only two white rot strikes were reported in the Central Valley this year. A combination of high soil temperatures and bulb development were not conducive to sclerotia infection and reproduction of the fungus. Much of the onion and garlic was grown outside of the normal production areas as processors and handlers had to source fields with reliable ground water sources. Downy mildew pressure was very severe in desert onion crops this year as above-average rainfall occurred during the growing season. Because of early summer rains and warm temperatures in the Central Valley, conditions for garlic rust infection periods were favorable, and fields were treated several times to get adequate control. Seed corn maggot/onion maggot: Severe pressure, primarily from seed corn maggot, was noted in the Tulelake area of northern California. Seed treatments with spinosad have given excellent control in the past - far superior to in-furrow treatment with chlorpyrifos. This year, the seed treatments did not provide adequate control, and in-furrow chlorpyrifos treatment was significantly better. We think the method by which seed was treated may have caused the product to wash off the seed and, thus, did not protect the seed.

Georgia report (given by Ron Gitaitis):

There was an unusual amount of Botrytis leaf blight in some onions in early March. The overriding factor was that in the majority of these fields in which it was observed, there was a delay in the application of an SDHI product like Pristine, Fontelis, or Endura. Most organic fields suffered drastically from these infections as well. There was also some crop loss due to hail damage and heavy winds that laid down some foliage prematurely. There were a fair number of fields with onions experiencing some type of tip die-back. At the time it seemed that each field had something different going on (low pH, excessive Goal injury, etc.); however, they were spread over a multi-county area. Nothing was ever cultured from these onions at the UGA Plant Disease Clinic. There was a fairly severe outbreak of center rot in approximately 900 acres of onions grown in southern Georgia and northern Florida (outside of the defined Vidalia onion zone as defined by the marketing order). This outbreak occurred on new ground as well as on land previously used to produce onions. County agents made the observation that most of the onions were planted behind corn. There also was an unusual outbreak of center rot caused by Pantoea ananatis in the heart of the Vidalia onion-growing region (Toombs and Tattnall Counties). Particularly hard hit were the bulbs from the middle maturity group. Furthermore, those infections were somewhat unusual for center rot in that typical necrosis of upper leaves was absent. Instead, there generally was a reddish-colored leaf in the neck of the bulbs observed at grading, but it obviously did not originate from a dying leaf in the top foliage. A few millimeters below the discoloration in the neck, a very small area of grayish, gummy tissues developed. This discoloration and texture remained restricted and did not spread in to the rest of the bulb. It was speculated that physiological conditions initiated the syndrome resulting in secondary colonization by P. ananatis. One observation in that regard was that the middle maturity group experienced unusually high temperatures at a critical phase of bulbing when nutrients were being relocated from foliage to bulb. It was speculated that high temperatures at that critical period, in combination with P. ananatis, may have caused the unusual symptoms. Finally, there is a substantial amount of seedling blight caused by Pantoea ananatis in the seedbeds that are now being transplanted for the 2016 crop. It will be interesting to see if this plays out in to having increased center rot problems this spring.

Oregon Treasure Valley (report given by Clint Shock):

There have been a lot of heat units in the Treasure Valley this past season, and very little irrigation water. The season started very early. Record heat units were recorded in the 2014 season and again in the 2015 season. Onion bulbs aren’t finishing completely. The predominant symptom Clint has seen is not the dry scale reported by Lindsey, Tim, and Stuart (see below), but incomplete top end of the fleshy scales. Some cultivars seem worse affected than others, but it’s not clear if there’s a cultivar trend because of many confounding factors. They’re also seeing more bacterial bulb rots associated with this, and Fusarium proliferatum infection of these symptomatic bulbs has been very spotty. They don’t know what’s causing the dry upper end of all the fleshy scales. Some growers have shortened their rotations a lot, which may be contributing to problems. Thrips and IYSV were less severe than usual, despite the heat stress, because most growers have implemented good management programs.

Washington (report given by Lindsey du Toit and Tim Waters):

It was a very warm season in Washington State with high temperatures early in the season and extended periods of heat stress (22 days >100^oF in the Tri-Cities area, and the warmest temperature of 113^oF was recorded in late June). As a result, crops matured 2 to 3 weeks earlier than normal, and thrips numbers were very high early during the cropping cycle. Thrips damage was quite severe in some crops, as was IYSV incidence in some bulb crops in relatively close proximity to onion seed crops. In some fields, the early maturity resulted in smaller-than-normal bulb size and, therefore, lower-than-average yields. There was also significant damage from internal dry scale, a physiological response that appears to be triggered by extended periods of heat stress, and often is accompanied by secondary colonization of the collapsed, internal fleshy scales by bacteria and/or fungi. Some entire onion crops and bulb lots in storage were abandoned as the affected bulbs could not be culled effectively (symptoms are almost entirely internal). Fall temperatures were also warm, making good curing conditions in most onion crops. A few crops received late rain after undercutting and/or windrowing, which will likely result in decreased storage quality. Black mold incidence (exterior of bulbs) was at significant levels in some fields due to warm temperatures. The warm fall also resulted in significant damage to fall-planted, overwintering crops from onion leafminer. Normally, cool fall temperatures reduce their activity, but not this season. Some overwintering bulb crops were also damaged by fall armyworm and had to be treated for this pest. Overall, a rough year for onions in central Washington and there is concern about how bulbs will fare in storage.

Discussion ensued about heat stress and some of the other problems growers have been experiencing in the Pacific Northwest with some of the growers present at the meeting. One grower stated that onion seed alone costs ~$600/acre.

New Mexico (report by Mark Uchanski):

New Mexico onion growers have not reported problems with IYSV this season. They’ve had typical thrips and pink root pressure. Conditions have been moderate and slightly cooler than normal, with normal precipitation. Yields are OK. It’s been a good season overall.

Mark stated he would like to put the W2008 nomination in again for the Western Association of Agricultural Experiment Station Award. Seed the Open Discussion items below.

New York (report given by Christy Hoepting):

New York onion growers experienced a very dry start to the season (May), but June was very wet and some growers lost onion stands. It was a moderate season overall with consistent rains that resulted in good yields in general. Thrips were relatively well controlled as a result. There were a few outbreaks of downy mildew and Stemphylium leaf blight. Bulb rots were at average levels. In some grower-cooperator, bacterial rot field trials, soil fumigation with chloropicrin had no significant effect on soil populations of the three main onion bacterial bulb rot pathogens (Burkholderia cepacia, Enterobacter ludwigii, and Pantoea ananatis) or on the incidence of bulb rots at harvest. Applications of TerraClean likewise had no significant effect on the numbers of these bacteria in the soil or bulb rots at harvest. Applications of a vermicompost extract (‘worm poop tea’ as Christy’s daughter called it) had no significant effect on bulb rots when applied as a drench, but dipping transplant seedlings in the extract prior to transplanting reduced the incidence of bacterial rot by about 50%. One grower made weekly applications of ‘pool chlorine’ to half of a field of onions at a rate of 1 gal of product/1,000 gal tank of water (Steve Beer didn’t know the chlorine concentration of the product, but estimated the chlorine application was at ~100 ppm). The incidence of bulb rot at harvest was reduced 60% compared to the non-treated half of the field, and the grower estimated a 22% increase in bulb yield. The treated part of the field lodged 2 weeks later than the non-treated part of the field.

Clint Shock discussed the recommended use of chlorine dioxide rather than other forms of chlorine. Bill Dean noted that some growers in the Columbia Basin who use pivot-irrigation routinely apply chlorine at 1 gal/hour (~1 ppm chlorine) using a 12.5% a.i. commercial product to clean irrigation water and equipment (sometimes at every irrigation).

Seven onion cultivars were evaluated by Brian Nault’s program for onion thrips resistance in New York. Six of the seven cultivars were short-day onions bred for southern production areas, while the other cultivar was bred for intermediate-day growing conditions. Unfortunately, the short-day cultivars did not grow well under western New York’s environmental conditions, and generally produced small plants and unmarketable bulbs; thrips resistance could not be assessed accurately. The intermediate-day cultivar showed signs of partial thrips resistance, but bulb yields were significantly less than standard cultivars for the region. Nonetheless, this intermediate-day onion cultivar shows promise for future thrips-resistance breeding projects.

Utah (report given by Dan Drost):

2015 has been a good year overall for Utah onion growers. 2015 was one of the hottest seasons on record and yet there were no days in Utah >100^oF, which was surprising. The record heat was largely a result of warm nights. Overall bulb yields and quality were good. Thrips were not excessive. IYSV came late into most fields (about the time of lifting), so there was little effect on yield. Dan has WSARE funding for a multi-year project looking at field border management for thrips and IYSV (see Focused Talks below).

Focused Talks

Presentations were given from 10 am to ~3 pm (excluding the lunch hour) on focused topics, as detailed in the meeting program (contact individual presenters to request copies of their presentations):

Progress in managing leaf diseases of onion in New York, featuring Stemphylium leaf blight - Christy Hoepting (Cornell University Cooperative Extension)

How fertility can affect sour skin severity and the expression of proteins associated with the plant systemic acquired resistance (SAR) pathway - Ron Gitaitis (Univ. of Georgia)

White rot management in garlic and onions and California’s “Water Woes” - Bob Ehn (CA Garlic and Onion Research Board)

Determining the presence of endophytic pathogenic bacteria in non-symptomatic onion necks or bulbs - Steve Beer (Cornell Univ.)

Onion internal dry scale: An emerging problem associated with climate change in the Pacific Northwest? - Lindsey du Toit (Washington State Univ.)

Systems Drivers for Managing Thrips/IYSV: Rotations, Borders and Nutrition Influences - Dan Drost (Utah State Univ.)

Controlling Insects Impacting Columbia Basin Onion Producers - Tim Waters (Washington State Univ.)

Onion insect pest management in onion with insecticides – the challenges ahead - Brian Nault (Cornell Univ.)

Open Discussion – Other Research Needs, Issues, Future Focus

September 30, 2017 is when the current W2008 expires:
- We need to write a new W3008 proposal in 2016, to be submitted before the W2008 expires.
- The group agreed we should consider a new title that it not focused as intensely on thrips/IYSV because of the large success in managing these problems in onion and the emergence of other major issues for onion growers across the USA. An example of a suggested title is “Integrated Onion Pest and Disease Management” (with added terms such as “frontlines” or “solutions”).
- A subcommittee of volunteers was formed to write this document: Brian Nault, Dan Drost, Hanu Pappu, and Lindsey du Toit.

There is a need for a standing NARC planning committee to streamline the planning and succession process. This will be discussed in Savannah, GA in 2016

Mark stated he would like to put the W-2008 nomination in again for the Western Association of Agricultural Experiment Stations Award. Steve Loring indicated the due date in the Directors’ Office is February 28, 2016.

Brian Nault thanked Dan Drost and the Utah Onion Association for organizing this meeting in Salt Lake City.

Election of new W2008 secretary for 2016

Christy Hoepting from Cornell University kindly agreed to be the next Secretary. Officers for 2016:

Past Chair: Mark Uchanski

Chair: Tim Waters

Vice Chair: Lindsey du Toit

Secretary: Christy Hoepting

History of W1008/W2008 meetings for a historical perspective, compiled by Mark Uchanski and Chris Cramer:

2019: Internat. Soc. Edible Alliaceae with NOA, NARC, and W3008 in Madison, WI - summer

2016: NARC + NOA combined with W2008 in Savannah, GA

2015: W2008 in Salt Lake City, UT

2014: NARC + NOA and W2008 in Scottsdale, AZ

2013: W2008 in Denver, CO

2012: NARC and W2008 in Las Cruces, NM

2011: W1008/W2008 in Las Cruces, NM

2010: NARC and W1008 in Reno, NV

2009: W1008 + NOA in San Antonio, TX - Dec.

2008: W1008 in Denver, CO - Jan; NARC and W1008 in Savannah, GA - Dec.

2007: W1008 in Denver, CO - Jan.

2015 Attendees:

	Name	Affiliation/Institution	E-mail address
1	Steve Loring	NMSU-AES	sloring@nmsu.edu
2	Mark Uchanski	NMSU/CSU	mark.uchanski@colostate.edu as of Dec. 2015
3	Lindsey du Toit	WSU	dutoit@wsu.edu
4	Kenny McFarland	Utah onion grower	kennymcfarlandfarms@gmail.com
5	Hanu Pappu	WSU Pullman	hrp@wsu.edu
6	Robert Ehn	CA Garlic and Onion Res. Brd	robertehn@sbcglobal.net
7	Steve Beer	Cornell University	svb1@cornell.edu
8	Diane Alston	USU	diane.alston@usu.edu
9	Christy Hoepting	Cornell University	cah59@cornell.edu
10	Sarah Pethybridge	Cornell University	sjp277@cornell.edu
11	Brian Nault	Cornell University	ban6@cornell.edu
12	Bill Dean	River Point Farms	bill.dean@riverpointfarms.com
13	Kerrick Bauman	L&L Ag Production (WA)	kerrick@llfarms.com
14	David Whitwood	Crookham Company	davew@crookham.com
15	Ron Gitaitis	University of Georgia	dronion@uga.edu
16	Claudia Nischwitz	Utah State University	claudia.nischwitz@usu.edu
17	Tim Waters	WSU	twaters@wsu.edu
18	Clint Shock	OSU	clinton.shock@oregonstate.edu
19	Juan C. Brevis	Bayer Vegetable Seeds	juan.brevis@bayer.com
20	Morgan Reeder	Grower	mlreeder@yahoo.com
21	Curtis L. Marble	Grower	clmarblefarms@gmail.com
22	Lisa Marble	Grower	lisasmarble@gmail.com
23	Dan Drost	USU	dan.drost@usu.edu

Minutes Attachment:

W3128 Minutes2015 (002).docx

Accomplishments

Objective 1. Evaluate onion germplasm for greater levels of tolerance to Iris yellow spot virus (IYSV), other pathogens and thrips.   Colorado (T. Gourd)- Two onion variety trial sites were set up at Sakata Farms locations along the Front Range of Colorado. The Howard Farm averaged only 6.2 thrips per onion plant, and the Zaiss location averaged 14.8 thrips per plant. This low thrips pressure could explain why very little Iris Yellow Spot Virus (IYSV) was observed at either location in 2015. New Mexico (C. Cramer) – In the previous year, germplasm lines were identified that possessed a reduced number of thrips per plant or less severe IYS disease symptoms than most entries. Seed productions of these lines were necessary to have ample seed quantities for distribution in the future. A total of 56 germplasm lines were regenerated using a total of 123 different crossing cages.   Original, intermediate, and advanced FBR-selected populations and one resistant and one susceptible check were evaluated for resistance to FBR. Both the resistant and susceptible check entries exhibited a high level of disease severity and incidence. With the high rate of disease development throughout the study, many of the selected populations did not perform well in terms of disease severity and incidence. The inoculation method of 3 x 105 sporesml-1 of FOC placed on a cut basal plate was very effective at causing disease in most bulbs. Selections were made for FBR-resistant bulbs using this method. In addition, seed was produced of FBR-resistant selections made in 2014. Seed was produced from a total of 22 different germplasm lines associated with this project. This will be used for evaluations to ascertain additional progress made for resistance to FBR.   New York (B. Nault, S. Beer, S. Pethybridge & C. Hoepting) – Seven onion cultivars were evaluated for onion thrips resistance in New York. The short-day onion cultivars did not grow well under New York’s environmental conditions and generally produced small plants and bulbs; thrips resistance could not be accurately assessed. The intermediate-day onion cultivar showed signs of partial thrips resistance, but bulb yields were significantly smaller than standard cultivars. Nonetheless, this intermediate-day onion cultivar shows promise for future thrips-resistance breeding projects. OREGON - (S. Reitz, C. Shock, E. Feibert, A. Rivera, & M. Saunders) Early maturity and full season onion variety trials were conducted in 2015. The trials were grown under drip irrigation. All varieties were evaluated for their yield, maturity and susceptibility to thrips damage and IYSV. Varieties had significant differences in IYSV in 2015.   Thrips populations and IYSV incidence were compared among four experimental breeding lines from Chris Cramer, NMSU, and three commercial cultivars. The experimental lines tended to have lower populations of thrips and IYSV severity than the commercial cultivars. <h4> </h4> Utah (D. Drost) - Twenty-nine (29) commercially available Spanish onion cultivars were assessed for productivity, maturity and rated for IYSV. While symptom expression of IYSV in 2015 was very low, all varieties evaluated showed visual evidence of IYSV under field conditions. IYSV had little impact on onion bulb yield as summer conditions were favorable for plant growth and IYSV incidence occurred very late in the season. More work on the relation between IYSV incidence and storage is needed.   Washington (T. Waters, L. J. du Toit, H. R. Pappu & C. Wohleb) - Onion genotypes (n = 35) were evaluated for resistance to stunting caused by Rhizoctonia solani anastomosis group (AG) 8 in a growth chamber at 15 oC. The trial was repeated. Resistance was defined as a lack of significant difference in plant height, root length, and/or total dry biomass between inoculated and non-inoculated plants of the same genotype. Of the 35 genotypes evaluated, 3, 16, and 3 demonstrated partial resistance to R. solani AG 8 for plant height, root length, and total biomass, respectively. Plant height, root length, and biomass of PX07713218 were not affected by the fungus in either trial; and R14885, R14888, and SN307 displayed partial resistance in both trials for two of the three onion growth parameters measured, and in one of the two trials for the third parameter. These four genotypes could be used in onion breeding programs to develop cultivars partially resistant to stunting caused by R. solani AG 8.   Objective 2. Investigate thrips biology and IYSV epidemiology to improve management strategies. New York (B. Nault, S. Beer, S. Pethybridge & C. Hoepting)- Co-applications of insecticides with either a non-ionic surfactant (Induce), a methylated seed oil (MSO), a mineral oil (JMS Stylet oil) or an organosilicone (Silwet L-77) were more effective for managing onion thrips than when insecticides were used alone. None of co-application treatments exacerbated the incidence of foliar diseases such as botrytis leaf blight, downy mildew, Stemphyllium leaf blight and purple blotch. Early-season management of onion thrips continues to be most effective beginning with Movento compared with other products like Radiant. A new product, Minecto Pro, which includes a combination of abamectin and cyantranilprole, was effective in managing onion thrips. The efficacy of Minecto Pro was similar to Exirel (cyantraniliprole), but numerically better than Agri-Mek. Based on historical levels of onion thrips control using Radiant (spinetoram) in New York, there is a downward trend in the level of control over the past decade suggesting that resistance to spinetoram may be developing in onion thrips populations. OREGON - (S. Reitz, C. Shock, E. Feibert, & M. Saunders)Two insecticide rotation trials were conducted to evaluate the effectiveness of various insecticides in managing thrips and IYSV. One trial included all foliar applied insecticides, and another trial featured insecticides applied through drip irrigation and by ground application. Movento and Agri-mek were effective in early season thrips management. Using moderately efficacious insecticides, such as azadirachtin at the beginning of a spray program, has been encouraging. This use pattern allows applications of Movento to be made later in the season so that Radiant remains the most effective insecticide for mid to late season thrips management.   Programs with drip applied products performed as well as foliar applied products. Drip applications may reduce grower expenses by reducing overall application costs. <h4> </h4> Utah (D. Alston, D. Drost & C. Nischwitz) – Onion thrips and IYSV were evaluated in field and research trials from June until September. Thrips densities on plants were very low in June (10/plant), increased to moderate levels in July (36/plant) and were quite high in late August (92/plant) as the onions began to mature. There was no difference in thrips numbers between the different nitrogen levels in 2015. A likely reason is that all onion plots sampled in 2015 followed three previous years of alfalfa and one year of onion production. Alfalfa may have increased soil nitrogen levels thus negating differences between high and low nitrogen application rates. IYSV levels increased throughout the summer but did not impact productivity. Sustainable production occurs when inputs, onion thrips, and IYSV are properly managed. Growers in Utah report little difficulty with thrips and IYSV severity was low in 2015. Growers are using USU research findings on lowering nitrogen input levels, working harder to keep field border weed free, and exploring the use of alternative crop rotations to help manage thrips numbers and IYSV incidence. Selected weeds growing next to onion fields were sampled for IYSV and thrips in the 2015. Weeds found with thrips (adults, nymphs and eggs) include bindweed, flixweed, sowthistle, common mallow, and foxtail barley. Identification of IYSV hosts that can serve as a green-bridge from year-to-year is critical to target, treat, and remove plants with IYSV growing near onions..   Washington (T. Waters, L. J. du Toit, H. R. Pappu & C. Wohleb) -Field plots of onion in Pasco, WA and grown using drip irrigation. Plots were established in a randomized complete block design with 4 replications. Foliar applications were made with a CO2 pressurized sprayer. Sprinkler chemigation applications were made with a trailer-mounted research sprayer applying and drip applications were made by injecting insecticides into individual drip lines. Efficacy was evaluated four or five days after each application by counting the number of immature and adult thrips per plant on 10 individual plants per plot. At the end of the growing season, onion yield and size were evaluated.   Using insecticides that are effective at controlling thrips increases yield and size class of dry bulb onions. Radiant and Lannate were found to be the most effective products while Movento, Verimark/Exirel and AgriMek provided good suppression of onion thrips. We also found that Radiant was more effective in the early season compared to Movento. Chemigation was an effective way to apply Lannate, Exirel and Radiant. Verimark was also effective when applied via drip injection.   Acibenzolar-S-Methyl (ASM) is a functional analog of salicylic acid (SA) that activates local and systemic acquired resistance (SAR) responses in plants against a wide variety of pathogens. To explore the possibility of utilizing SAR as a control option, we first used two different hosts of IYSV, Datura stramonium and Nicotiana benthamiana, to study the ability of ASM in triggering SAR against IYSV infection. Quantitative descriptors based on both symptom expression and relative levels of IYSV nucleoprotein and viral small RNA were developed and used to determine the SAR in ASM- and buffer-treated plants. A significant reduction in virus levels in ASM-treated plants was noticed by ELISA and PCR. The level of SAR response was also assessed by measuring the IYSV lesion size and number on the inoculated leaves of ASM-treated plants. ASM-treated plants showed reduced symptoms compared to buffer-treated plants. This study could be useful in potentially developing novel SAR-based options for virus management.     Objective 3. Investigate the biology, ecology and epidemiology of other pathogens to improve management strategies. Colorado (T. Gourd)- An evaluation of Mycorrhizal Fungi on Commercially Grown Onions in Colorado was conducted during the 2015. The objectives of this study were to use large scale on-farm test to demonstrate efficacy of MYKE Pro Specialty Crop P endomycorrhizal inoculant. The active ingredient is Glomus spp. We evaluated for enhanced seedling growth, increased pathogen resistance/protection of onions and increased onion yield (quality and quantity). <ul> <li>The bottom line was no economic advantage was seen using a planter box application of MYKE Pro Specialty Crop P endomycorrhizal inoculant at two farm locations in 2015</li> </ul>   Georgia (R. Gitaitis, B. Dutta, D. Riley, R. Srinivasan, & A. Watson-Selph) – Previously developed regression models consisting of concentrations of cations and cation ratios accurately predicted sour skin severity. In 2015 these models were used to identify healthy bulbs that had the highest and lowest levels of sour skin. RNA was extracted and used for transcriptomic analysis. Many proteins were expressed at significantly higher levels in bulbs with a higher copper to iron ratio which was also associated with reduced sour skin levels. Increased levels of important proteins that particularly have known functions in the systemic acquired resistance (SAR) pathway in plants, included: >5,000 fold increase in universal stress protein A (USPA is very similar to Pto which is known to convey resistance in tomato); > 4700 fold increase in B2 protein (increases hydrogen peroxide levels, a precursor for salicylic acid); > 900 fold increase in enhanced disease resistance protein (EDR1 is involved in a MAP kinase cascade that regulates salicylic acid dependent defense responses); and > 3900 fold increase in glutaredoxin (known to interact with non-expressor pathogenesis-related protein 1 (NPR1) which has a feedback control of salicylic acid production). The most important example of an elevated protein level of a SAR-connected protein in bulbs with a higher copper to iron ratio was a > 5000 fold increase in the expression of pathogenesis-related protein 1 (PR1). PR1 is known to be regulated through the salicylic acid pathway and is a plant resistance protein whose production is regulated by NPR1. The PR1 protein identified had 85% similarity with PR1 from garlic.   Field studies indicated that titanium dioxide nanoparticles doped with zinc, acibenzolar-S-methyl and cupric hydroxide had little effect on center rot. When the same treatments were evaluated in for postharvest rots due to sour skin caused by B. cepacia, cupric hydroxide applied weekly significantly reduced postharvest levels of sour skin. Evaluating acibenzolar-S-methyl in combination with different nutrients found that lowest levels of sour skin occurred in all treatments receiving gypsum. Onions with the highest levels of sour skin had all been treated with acibenzolar-S-methyl in combination with either iron, copper, manganese or zinc chelates. The highest level of sour skin occurred with the treatment of copper, calcium chloride, magnesium sulfate and acibenzolar-S-methyl and was significantly different from copper, calcium chloride and magnesium sulfate without acibenzolar-S-methyl indicating a possible negative interaction with the plant resistance inducing compound.   A paper was published in the J. Econ. Entomol. entitled “Thrips Settling, Oviposition and IYSV Distribution on Onion Foliage”. Results from studies confirmed that distribution of thrips adults, nymphs, and eggs were skewed toward the base of the plant. The settling distributions of thrips adults and nymphs differed slightly from the egg distribution. In a field study, the results suggested that adults of different species appear to segregate along leaf length. Finally, thrips oviposition on 2-cm segments and Iris yellow spot virus positive leaf segments were quantified in the field, irrespective of thrips species. Both variables demonstrated a very similar pattern of bias toward the base of the plant and were significantly correlated.   Idaho (B. Schroeder)- The impact of curing temperature and duration on the development of storage rot caused by the bacterial pathogens Pantoea ananatis, Pantoea agglomerans, and Pantoea allii on onion bulbs was completed. As with previous studies, it was determined that curing onion bulbs with cooler temperatures for a longer duration will reduce the amount of rot caused by these pathogens if the bulbs were infected prior to storage.   A DNA macroarray was developed for the detection of fungal and bacterial plant pathogens (26+) capable of causing onion bulb rot in storage. The DNA macroarray for the fungal pathogens was just evaluated for sensitivity and it appears to be able to detect ng levels of the pathogen present in a sample. It was determined that the DNA macroarray is able to detect the presence of Fusarium proliferatum in asymptomatic onion bulbs prior to curing. The DNA macroarray is being used to obtain pathogen incidence data to correlate with disease incidence in storage. A macroarray that readily detects latent infections by bulb rot pathogens will enable stakeholders to make informed storage management decisions.   New York (B. Nault, S. Beer, S. Pethybridge & C. Hoepting)- Bacterial Diseases of Onion Emphasis was placed on three bacterial pathogens, Burkholderia cepacia, Enterobacter cloacae and Pantoea ananati, known to cause great losses to New York onion growers. Plants were collected biweekly during the later two-thirds of the growing season from one grower in each of the three major onion-growing areas of New York State and analyzed to determine the degree of bacterial infection, infestation and susceptibility to the three bacterial pathogens. Very little infection was detected visually in any samples until the last two collections, a few weeks prior to harvest of the crop. Infestation of bulbs varied depending on the pathogen and the location from which the plants were collected. Overall, pathogenic bacteria were isolated and identified from (4 to 24%) of symptomatic bulbs of growing plants. This suggested the hypothesis that the degree of infestation with pathogenic bacteria may indicate the extent of decay at harvest or following storage. Generally, plants were susceptible to infection following inoculation with P. ananatis or B. cepacia at any age tested. Only 1 of 9 of the inoculated plants became symptomatic after prolonged incubation following inoculation with E. cloacae at the 6-leaf stage of growth. In controlled inoculation and environment studies conducted in the laboratory, conditions were discovered that were conducive to the initiation and development of infection of growing onion plants that had reached the “bulbing” stage when inoculated with pure cultures of B. cepacia. We evaluated four materials that may reduce bacterial rot. None of the materials had been tested rigorously previously for the control of bacterial rot of onions. The materials were: 1. Chloropicrin, 2. vermicompost extract, 3. TerraClear®5, and “Pool Chlorine”. Research plots were set up in 3 onion-producing regions of NY. At harvest bulbs were collected and each was cut and examined closely for evidence of bacterial decay. Based on these analyses, we concluded that the Chloropicrin fumigation did not affect rot, but vermicompost extract and TerraClear®5 both reduced the percentage of rot somewhat. Treatment with sodium hypochlorite not only reduced the percentage of rot, but yields in the treated plots were substantially increased. Clearly, additional testing of the three promising materials is in order.   Fungal Diseases of Onion Onion production in NY is affected by a complex of foliar fungal diseases including downy mildew (Peronospora destructor), Stemphylium leaf blight (SLB; Stemphylium vesicarium) and purple blotch (Alternaria porri). The objectives of this research were to quantify the prevalence and incidence of foliar diseases and determine the symptoms associated with each of the pathogens in the ‘target spot’ complex of onion. Stemphylium vesicarium was the most prevalent fungus associated with foliar disease in NY. The isolation frequency of S. vesicarium was not significantly affected by production type and was not significantly different in conventional and organic fields. Moreover, the frequency of the teleomorph of S. vesicarium, Pleospora allii was significantly higher in conventional fields than organic production. This may indicate that factors that are prevalent in conventional fields may be inducing the production of the teleomorph. The high frequency of S. vesicarium from foliar disease was irrespective of symptom type but most commonly with an asymmetric, necrotic lesion. In conventional fields, there was a low prevalence and incidence of Peronospora destructor, and Botrytis spp. The isolation frequency of Alternaria porri and A. alternata was significantly higher in organic than conventional production. These findings suggest the fungicides being used within conventional production are efficacious for the control of purple blotch, downy mildew and Botrytis spp. In 2015, a replicated field trial evaluated the relative efficacy of currently registered and perspective fungicides for control of SLB. It was a randomized complete block design with 18 treatments and 5 replicates. An untreated control with no pesticide applications and an untreated with only onion thrips and downy mildew maintenance sprays were included. A final SLB score was determined within each plot from six disease and plant health assessments from Aug-5 to Aug-30. A higher SLB score indicated more severe disease. All fungicide treatments had significantly lower SLB scores than the untreated (score 345), which was significantly lower than the untreated check with maintenance sprays (score 303). Maximum disease control was obtained with Luna Tranquility, Merivon, Inspire Super and Fontelis. Plots receiving fungicides belonging to FRAC 11 were not significantly different than the maintained untreated. Products with only FRAC 3 active ingredients and only FRAC 7 active ingredients provided significantly poorer disease control than Luna Tranquility, but not significantly different from Inspire Super or Fontelis, and between each other. The only product with just FRAC 9 was Scala, which provided mediocre control. SLB control was significantly improved when Scala was premixed with fluopyram (7) within Luna Tranquility. Another premix product with FRAC 9 was Switch, which performed similarly to Scala. Disease control in plots receiving Omega and Gavel were not significantly different to those receiving Scala and Switch. In conclusion, Luna Tranquility was the most efficacious fungicide for controlling SLB in onions and this was attributed to the presence of fluopyram (7). Generally, products belonging to FRAC groups 3 and 7 provided the best control of SLB. The lack of efficacy from strobilurin products is concerning and the subject of further studies. OREGON - (S. Reitz, C. Shock, E. Feibert, A. Rivera, & M. Saunders) In anticipation of the rules in the Food Safety Modernization ACT, research on onion production in relation to food safety continued in 2015 to compare the roles of wooden and plastic storage containers on contamination of onion bulbs with generic Escherichia coli, the FDA indicator for potential microbial contamination. E. coli levels of onions grown in furrow-irrigated plots using surface irrigation water with enhanced E. coli levels and harvested into old wooden boxes and sterilized plastic crates were compared with E. coli levels of onions grown under drip irrigation. After 6 weeks in storage, onions were prepared for shipment through removal of loose skin, roots and soil. Regardless of irrigation source, neither onions stored in plastic nor in wooden containers had detectable E. coli on the bulb exteriors or interiors. These results are consistent with our previous trials and indicate that storage container material does not affect the likelihood of E. coli contamination of dry bulb onions. We repeated field studies to evaluate if surface irrigation systems reusing water may deliver bacteria to onions. We tested the potential for furrow irrigation using canal water with moderate or high levels of E. coli contamination and drip irrigation using canal water and well water free of E. coli to deliver E. coli to onion bulbs. The four irrigation systems applied water to onion. Water was sampled hourly for E. coli and the lateral movement of E. coli in the soil solution was tracked by soil samples. Onions were sampled for E. coli contamination. Consistent with previous results, furrow irrigation delivered E. coli to the soil immediately adjacent to the onion bulbs. E. coli movement under drip irrigation was mostly confined to near the drip tape and very little reached the onion bulbs, indicating that drip irrigation did not directly deliver E. coli to onions. <h4>In Oregon, surface irrigation water is commonly used for drip irrigation. We evaluated the use of chlorine dioxide to reduce bacterial loads in surface irrigation water. Growers often routinely use injections of chlorine dioxide at the end of irrigation cycles to control the growth of algae in drip irrigation lines. The current rates of chlorine dioxide for drip line maintenance (3 ppm) virtually eliminate E. coli.</h4> <h4>Pennsylvania (B. Gugino) – In PA and NY, annual losses from bacteria range from 5 to 40%. However, these losses are variable, between fields and within the same field; in many cases the full extent of disease losses is not evident until harvest or after post-harvest storage. During 2015, efforts were directed towards the development of targeted research-based management strategies for reducing harvest and post-harvest losses due to bacterial bulb rots described below.</h4> <h4>A replicated field trial evaluated the effect of nitrogen application timing and rate on onion bacterial disease incidence and marketable yield. The trial was a split plot randomized complete block design with nitrogen application timing as the whole plot and application rate as the sub-plot. Preliminary data analysis indicates that marketable yields were most influenced by disease pressure (inoculated vs not inoculated), the nitrogen rate (more nitrogen increased yields) rather than the timing of application.</h4> <h4>Host resistance is one of the most important tools available for disease management. Identification of less susceptible cultivars that meet the marketing program criteria would provide growers with another management tool. A field trial was conducted to evaluate the susceptibility of ten onion cultivars to center rot. Each plot was subdivided and two alternate 20 ft rows were toothpick inoculated with a bacterial suspension containing a mix of three isolates of Pantoea ananatis and P. agglomerans, the two causal pathogens of center rot. Significant differences in yield between the cultivars were observed with cv. Great Western and Expression being the highest yielding and Sedona, BGS 300F1 Blush and Aruba being the lowest yielding. Cv. Aruba with the lowest yields also had the highest incidence of bacterial bulb rot at harvest as well as foliar disease symptoms during the season.</h4> <h4> </h4> Washington (T. Waters, L. J. du Toit, H. R. Pappu & C. Wohleb) Onion pink root Serenade Soil trial (L.J. du Toit): A field trial was completed to evaluate Serenade Soil for management of onion pink root in a drip-irrigated, certified organic, onion bulb crop of the cv. Merenge in a commercial crop. Replicate plots of each of two Serenade Soil treatments were compared with control plots in each of two trial sites at the same field, one trial site with severe pink root pressure compared to the other site as a result of 2- vs. 4-year rotations out of onion, respectively. Serenade Soil treatments were applied after planting in a band over each double-row using a CO2-pressurized backpack sprayer on 3 April. A second application of Serenade Soil was made on 24 April, and a third application on 22 May. In both trials, onion stands were significantly less in plots treated with Serenade Soil once or three times compared to control plots. The incidence of bulbs with pink root symptoms averaged 56.7% in the site with a 4-year rotation out of onions, compared to 100% pink root in the site with a 2-year rotation. In both trials, application of Serenade Soil once at 4 qt/acre or three times at 3-week intervals at 2 qt/acre/application did not reduce the incidence or severity of pink root.   Onion stunting caused by Rhizoctonia spp.: (L.J. du Toit): Onion stunting is an important soilborne disease on very sandy soils in the Columbia Basin. Isolates of Rhizoctonia spp. were obtained from soil and onion plant samples collected from inside and outside patches of stunted plants in 29 fields. Based on sequence analysis of the internal transcribed spacer (ITS) rDNA region, 13 anastomosis groups (AGs) or subspecies were detected. The most frequent was Waitea circinata var. circinata (25%), followed by Rhizoctonia solani AG 3 (17%), R. solani AG 4 (14%), Ceratobasidium sp. AG A (10%), R. solani AG 8 (7%), Ceratobasidium sp. AG K (6%), R. solani AG 2-1 (6%), W. circinata var. zeae (6%), R. solani AG 5 (4%), Ceratobasidium sp. AG G (2%), R. solani AG 11 (2%), and R. solani AG 1-1B and AG 10 (each <1%). However, the distribution of AGs and subspecies varied depending on whether soil or onion plant samples were collected within or adjacent to patches of stunted onion plants. In an attempt to predict the risk of onion stunting prior to planting, DNA concentrations of AG 2-1, AG 3, AG 4, and AG 8 were quantified from bulk soil samples from nine fields. Pre-plant DNA concentrations did not correlate significantly with the amount of stunting observed during the growing season. In contrast, the frequency of isolation and DNA concentration of R. solani AG 8 detected in soil sampled during the growing season were greater from inside patches of stunted onion plants than from adjacent healthy areas of one but not for another onion crop. AG 2-1, AG 3, and AG 4 DNA concentrations did not differ significantly in soil sampled inside vs. outside stunted patches in the fields sampled in either year. Relationships between the number of bulbs harvested or bulb weight vs. severity of stunting were defined using correlation and regression analyses for six onion cultivars. Onion stunting reduced the average marketable bulb yield by 25 to 60% within stunted patches of the six cultivars. Stunting did not reduce onion plant stand but consistently reduced bulb size, and yield.   Objective 4. Facilitate interaction and information transfer between W2008 participants, the onion industry and other stakeholders. Colorado (T. Gourd)- The Northern Colorado Onion Variety Trials Field Tour was held on Friday, September 4.   Idaho (B. Schroeder)- The University of Idaho Plant Pathology laboratory has provided diagnostic services to the onion stakeholders throughout 2015 using the DNA macroarray and detected Fusarium proliferatum a fungal pathogen. New York (B. Nault, S. Beer, S. Pethybridge & C. Hoepting)- As a result of onion growers’ following the Cornell-recommended IPM program for thrips, effective management of onion thrips was achieved with nearly 2 fewer insecticide applications. This reduction in insecticide use translated into an average savings of $50 per acre in insecticide costs. We estimated that 75% of the onion growers in New York have adopted this program, thereby saving these growers approximately $375,000 in 2015. Oregon - (S. Reitz, C. Shock, E. Feibert, & M. Saunders)-The Oregon project has continued to transfer information pertinent to IYSV and thrips biology and management to growers, other onion industry parties, and the public through numerous meetings, field days, workshops, publications, and the internet. The Malheur Experiment Station hosted field days on July 8 and August 25 and a stop on the NOA tour on July 17. Results have also been presented at the Idaho-Malheur County Onion Growers Association Meeting, Pacific Northwest Vegetable Association Meeting, and the Treasure Valley Irrigation Conference.   <h4>Pennsylvania (B. Gugino) – In Pennsylvania the research results were disseminated at several local and regional vegetable grower meetings/conferences both in-state and out-of-state throughout 2015. Results were also disseminated throughout the season through one-on-one with the growers. We continued to disseminate the Diagnostic Pocket Series as well as the Onion Health Management and Production bulletin to interested growers and other stakeholders and wrote an article for the grower publication Onion World.</h4>   Utah (D. Alston, D. Drost & C. Nischwitz) – USU hosted; winter onion meetings (56 attended) in February 2015 in Brigham City, UT; a summer field tour (52 attended) in August 2015; and Drost gave two presentations on Utah’s systems approach to managing onion thrips and IYSV to the onion industry (220 attended) of Idaho, Oregon and Washington in November 2015 (see dissemination section). Two presentations were made at the W2008: Biology and Management of Iris Yellow Spot Virus, Other Diseases, and Thrips in Onions Regional Meetings on Dec 10 in Salt Lake City describing Utah based research findings.   Washington (T. Waters, L. J. du Toit, H. R. Pappu & C. Wohleb) In Washington, results from the thrips insecticide efficacy results were shared at the WSU Onion Field Day, several grower meetings, and by a written report. Using the most effective insecticides improve their yields and reduce the incidence of IYSV, therefore improving yield, quality, and profitability of producers. An impact report by Washington State University (<a href="http://ext100.wsu.edu/impact/improving-insect-management-in-dry-bulb-onions-in-the-columbia-basin/">http://ext100.wsu.edu/impact/improving-insect-management-in-dry-bulb-onions-in-the-columbia-basin/</a>) cites the importance of this work and how widely adopted these practices are by Washington Onion Producers

Publications

Alston, D. G., 2015. Growing cover crops for pest management. Utah Pests News, Utah State University Extension, 9(Fall). <a href="http://utahpests.usu.edu/files/uploads/UtahPests-%09Newsletter-fall15.pdf">http://utahpests.usu.edu/files/uploads/UtahPests-Newsletter-fall15.pdf</a> Asselin, J.E., J.M. Bonasera, and S.V. Beer. 2016. PCR Primers for detection of Pantoea ananatis, Burkholderia spp., and Enterobacter sp. from onion. Plant Disease. 100: 1-11. Asselin, J. E., J.M. Bonasera, and S.V. Beer. 2015. New York bacterial rot research update: Critical factors. Onion World 31(3):20-23. Buckland, K., Alston, D. G., Reeve, J., Nischwitz, C., & Drost, D. T. Trap crops in onion to reduce onion thrips and Iris yellow spot virus: Environmental Entomology/Entomological Society of America. (Submitted). du Toit, L.J. and Derie, M.L. 2015. 2014 Onion pink root Serenade Soil efficacy trial, Connell, WA. Research report submitted to Bayer CropScience, Feb. 2015. 4 pp. du Toit, L.J., Waters, T., and Reitz, S. 2016. Internal dry scale and associated bulb rots of onion. Extension Bulletin PNW 686. In press. du Toit, L.J., Waters, T., and Reitz, S. 2015. Internal dry scale and associated bulb rots: Bane of the 2014 Pacific Northwest onion season. Onion World May/June 2015:4-7. Gill, H.K., H. Garg, A.K. Gill, J.L. Gillett-Kaufman, and B.A. Nault. 2015. Onion thrips (Thysanoptera: Thripidae) biology, ecology, and management in onion production systems. J. Integ. Pest Mngmt. 6(1): 6. DOI: 10.1093/jipm/pmv006. Gugino, B.K. and E.E. Pfeufer. 2015. Bacterial disease management of onion. 2015 Mid-Atlantic Fruit and Vegetable Convention Proceedings, Pennsylvania Vegetable Growers Association, Richfield, PA. pp. 79-81. Hoepting, C.A. 2015. New top performing pesticides now registered in onions in New York. March 1, 2015 Veg Edge, 11(3): 136-145. Hoepting, C.A. 2015. Onion thrips breaking spray threshold in upland transplanted onion.  May 27, 2015, 2015 Veg Edge, 11(7): 9-10. Hoepting, C.A. 2015. The conflicts of simultaneous control of onion thrips and Botrytis leaf blight in onions. June 17, 2015 Veg Edge, 11(10): 6-7. Hoepting, C.A. 2015. Management of Summer Leaf Diseases in Onion: Target Spot Diseases. July 1, 2015, 2015 Veg Edge, 11(13): 6-7. Hoepting, C.A. and B.A. Nault. 2015. Strategic Management of Onion Thrips in Onions. July 15, 2015, 2015 Veg Edge, 11(14): 4. Hoepting, C.A. 2015. Causes of Outer and Inner Leaf Dieback in Onions. July 22, 2015, 2015 Veg Edge, 11(15): 5. Hoepting, C.A. 2015. Scouting Tips for Identifying Downy Mildew in Onions. July 29, 2015, 2015 Veg Edge, 11(16): 5. Hoepting, C.A. 2015. Managing Downy Mildew of Onion: Control of target Spot Diseases is Critical. August 5, 2015, 2015 Veg Edge, 11(17): 4-5. Hoepting, C.A. 2015. Iris Yellow Spot Virus of Onion. August 12, 2015, 2015 Veg Edge, 11(18): 3. Hoepting, C.A. 2015. Using Ridomil to Manage Downy Mildew in Onion. August 12, 2015, 2015 Veg Edge, 11(18): 6. Hoepting, C.A. 2015. Managing Stemphylium leaf blight and downy mildew. Onion World, 31(7): 34-37. Maughan, T., D. Drost and N. Allen. 2015. Vegetable Irrigation: Onion. Utah State University Cooperative Extension Bulletin. <a href="http://digitalcommons.usu.edu/extension_curall/723/">http://digitalcommons.usu.edu/extension_curall/723/</a> Nault, B.A. 2015. Onion thrips management: Crisis averted? What’s next?, 4 pgs. Empire State Producers EXPO. January 22, 2015. Syracuse, NY.             <a href="http://www.hort.cornell.edu/expo/proceedings/2015/onions/Thrips%20management%25%0920crises%20averted.pdf">http://www.hort.cornell.edu/expo/proceedings/2015/onions/Thrips%20management%20crises%20averted.pdf</a> Nault, B.A. 2015. Onion maggot and onion thrips management in onion. Onion World 31(2):   16-19. Pappu, H.R. 2015. Thrips-transmitted Iris yellow spot virus – A threat to onion sustainability. Agricultural Research Journal 52: 10-12 Pfeufer, E., C. Hoepting, and B. Gugino. 2015. Advances in managing onion bacterial diseases in the Northeastern U.S. Onion World 31(6): 22-27. Rinehold, J., Bell, N., Waters, T.D., & McGrath, D. 2015. Vegetable Insect Pests. In Craig Hollingsworth (Eds.), 2015 Pacific Northwest Insect Management Handbook Corvallis, OR: Oregon State University. Sharma-Poudyal, D., Paulitz, T.C., and du Toit, L.J. 2015. Evaluation of onion genotypes for resistance to stunting caused by Rhizoctonia solani AG 8. HortScience 50:551-554. Sharma-Poudyal, D., Paulitz, T.C., and du Toit, L.J. 2015. Stunted patches in onion bulb crops in Oregon and Washington: Etiology and yield loss. Plant Disease 99:648-658. Sharma-Poudyal, D., Paulitz, T.C., and du Toit, L.J. 2016. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Plant Disease 100: accepted Nov. 2015 pending minor revisions, revised & re-submitted Dec. 2015. PDIS-10-15-1234-RE Shock, C.C., E.B.G. Feibert, A. Rivera, L.D. Saunders. 2015. Response of onion yield, grade,   and financial return to plant population and irrigation system. HortScience 50(9):1312-1318. Shock, C.C., J.M. Pinto, E.B.G. Feibert, and C.B. Shock. 2015. Optimal irrigation criteria for drip irrigated onions. Growing Produce. March 24, 2015. Smith, E.A. 2016. Patters of dispersal activity of onion thrips, Thrips tabaci Lindeman, in onion ecosystems. Cornell University, PhD. Dissertation. Pp. 131. Smith, E.A., M. Fuchs, E.J. Shields, and B.A. Nault. 2015. Long-distance dispersal potential for onion thrips (Thysanoptera: Thripidae) and Iris yellow spot virus (Bunyaviridae: Tospovirus) in an onion ecosystem. Environ. Entomol. 44(4): 921-930. DOI: 10.1093/ee/nvv072. Vahling-Armstrong, C., Dung, J.K.S., Humann, J.L., and Schroeder, B. K. 2015. Effects of postharvest onion curing parameters on bulb rot caused by Pantoea agglomerans, Pantoea ananatis and Pantoea allii in storage. Plant Pathology, http://onlinelibrary.wiley.com/doi/10.1111/ppa.12438/epdf Tripathi, D., G. Raikhy, and H.R. Pappu (2015). Movement and nucleocapsid proteins coded by two tospovirus species interact through multiple binding regions in mixed infections. Virology 478:143-53. doi: 10.1016/j.virol.2015.01.009 Tripathi, D., G. Raikhy, R. Dietzgen, M. Goodin, and H.R. Pappu (2015). In vivo Localization of Iris yellow spot virus (Bunyaviridae: Tospovirus)-encoded Proteins and Identification of Interacting Regions of Nucleocapsid and Movement Proteins. PLoS ONE 10(3): e0118973. doi:10.1371/journal.pone.0118973 Tripathi, D., and H.R. Pappu (2015). Evaluation of Acibenzolar-S-Methyl-Induced Resistance against Iris yellow spot tospovirus. European J. Plant Pathology 142:855–864. DOI 10.1007/s10658-015-0657-0 E. Waters, T.D. and Skoczylas, J.C. 2015. Thrips Control in Dry Bulb Onions in Washington State, 2012. Arthropod Management Tests. Report #E70. Waters, T.D. and Skoczylas, J.C. 2015. Thrips Control in Dry Bulb Onions in Washington State, 2014. Arthropod Management Tests. Report #E72. Waters, T.D. and Skoczylas, J.C. 2015. Thrips Control on Dry Bulb Onions Using Overhead Chemigation of Insecticides, 2014. Arthropod Management Tests. Report #E71. Wohleb, C.H. and Waters T.D. Yield, Quality, and Storage Characteristics of Onion Cultivars in the Columbia Basin of Washington. HortTech. Submitted. Zaid, A.M., J.E. Asselin, and S.V. Beer. 2016. Detection of Burkholderia cepacia in onion planting materials and onion seeds. Chapter 22 in M. Fatmi and N. W. Schaad, eds. APS Manual on Detection of Plant Pathogenic Bacteria in Seed and Planting Material. 2nd Ed. APS Press. St. Paul, MN. (In Press).

Impact Statements

The knowledge that higher curing temperatures exacerbate the development of storage rot caused by the bacterial pathogens provides stakeholders with a management decision tool. If they know that the crop is at risk for bacterial storage rot, they can choose to cure bulbs using lower temperatures. This will help to reduce losses due to onion bulb rots in storage and increase onion production efficiency and profitability.

Date of Annual Report: 12/08/2016

Report Information

Annual Meeting Dates: 12/03/2016 - 12/03/2016
Period the Report Covers: 10/01/2015 - 09/30/2016

Participants

See attached meeting minutes.

Participants Attachment:

W2008 Annual Meeting Minutes Dec 2016 FINAL.docx

Brief Summary of Minutes

See attached minutes.

The meeting was called to order at 10 am with state reports presented over ~90 minutes by participating members representing Georgia (by Ron Gitaitis), Colorado (by Mike Uchanski), New Mexico (by Chris Cramer), New York (by Christy Hoepting), Utah (by Dan Drost), Washington (by Tim Waters), and Wisconsin (by Mike Havey). Refer to the details covered in four pages of the minutes of the annual meeting for information from each state related to onion research and extension activities.

2017 Executive Committee of the proposed W3008:

Chair: Lindsey du Toit, Washington State University, responsible for chairing the 2017 W3008 annual meeting.

Vice-Chair: Christy Hoepting, Cornell University, responsible for writing/submitting the 2017 annual report.

Secretary: Beth Gugino, Pennsylvania State University, was voted in by members and is responsible for writing/submitting the annual meeting minutes.

Secetary-Elect: Bhabesh Dutta, University of Georiga.

Past-Chair: Tim Waters, Washington State University.

The location of the 2017 W3008 meeting was discussed, with preference for a more central location that is efficient for members across the USA to fly in/out. Chicago was recommended because of central location and ready access to airport hotels. Mary Hausbeck suggested having the meeting immediately preceding or after the Great Lakes Expo in Grand Rapids, MI in early Dec., as there is an onion session at this conference that many of our project members attend or have attended, and we could invite onion stakeholders from the conference to participate in the annual meeting. The Executive Committee was asked to reach a decision. [Subsequent to the annual meeting, a decision was reached to work with Mary Hausbeck and Ben Werling to have the W3008 annual meeting on Monday, Dec. 4^th, preceding the Great Lakes Expo (5^th - 7^th Dec.) in Grand Rapids, MI. Lindsey will work with Mary and Ben on a room reservation, accommodation options, etc.]

Proposal for W3008: Brian Nault led the writing of a proposal to extend the W2008 to the W3008, following expiration of the W2008 in 2017, with the new title “W3008: Integrated Onion Pest and Disease Management”. The following revised objectives are in the proposal, submitted to Steve Loring on 10 Dec. 2016 (submission deadline is January 15, 2017), along with a list of organizations that will be engaged by the W3008 project and a letter from Wayne Mininger on behalf of the National Onion Association, supporting the project:

Evaluate onion germplasm for resistance or tolerance to key pathogens and insect pests;

Investigate the biology, ecology and management of onion thrips and other pests;

Investigate the biology, epidemiology and management of onion diseases; and

Facilitate discussions among W3008 participants and onion stakeholders that will advance onion pest and disease management.

NOTE: Following this meeting, Steve Loring entered the objectives into the NIMSS system and requested everyone interested in participating in W3008 sign up by completing the Appendix E for the proposal. Steve noted the W2008 project will need an impact statement to tell the story of this 5-year project at the national level. Steve offered to take the lead using impact statements from previous annual reports, and will contact this group if needed. Multistate project proposals will be reviewed in spring 2017, with a call for additional information and a decision made in June/July. Steve Loring suggested compiling a list of potential reviewers for the W3008. Howard Schwartz can be recommended.

Federal award nomination for outstanding multistate projects: Steve Loring will submit a nomination of the W2008 for a federal award for an outstanding multistate project. Feedback from a previous nomination for this award will be considered in developing the nomination.

Alliumnet and Onion ipmPIPE websites: These websites do not appear to have been updated since Howard Schwartz retired. Mark Uchanski offered to follow up to see if these websites can be changed to become static or whether they should be removed. Mark also will check with NOA to see if the W1008 to W3008 annual reports may be housed on the NOA website. Lindsey enquired about the possibility of moving some resources to established, maintained websites, e.g., the Pacific Northwest Vegetable Extension Group (PNW VEG) website at (http://mtvernon.wsu.edu/path_team/vegpath_team.htm) with sections on onion diseases, pests, and other problems, as well as IPM resources: e.g. http://mtvernon.wsu.edu/path_team/onion.htm and http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion

W2008 Annual Report: Lindsey du Toit requested states submit their annual reports to her by 23^rd Dec. 2016 so she can compile the overall 2016 annual report and get it submitted before January 10^th, after which she’ll be traveling overseas (the deadline is January 15^th).

Onion Federal Grant Proposals:

The group discussed submitting a new USDA Specialty Crops Research Initiative (SCRI) onion proposal, pending the outcome of the USDA SCRI grant proposal submitted by Hanu Pappu, Mike Havey, Brian Nault, and Chris Cramer on thrips, IYSV, and white rot in 2016. Lindsey du Toit offered to lead a USDA SCRI grant proposal on onion diseases to be submitted in Nov. 2017, covering bacterial diseases, pink root, Stemphylium leaf blight, and other diseases. Members were asked to let Lindsey know if they are interested in participating in the proposal, and diseases on which they would like to help write the proposal.

The meeting adjourned at 2:08 pm

Minutes Attachment:

W2008 Annual Meeting Minutes Dec 2016 FINAL.docx

Accomplishments

Objective 1.  Evaluate onion germplasm for greater levels of tolerance to Iris yellow spot virus (IYSV), other pathogens and thrips. Colorado – More than 40 cultivars were evaluated for thrips tolerance and horticultural traits in replicated trials in northern and southern Colorado. Several high yielding varieties had appreciable tolerances to thrips. The cv. Yosemite had the fewest number of thrips/plant at two locations in northern Colorado. Several widely-grown varieties were evaluated for total metabolite content. Samples from University-sponsored trials in northern Colorado, southern Colorado, and the Columbia Basin of central Washington showed compositional differences based on variety and environment. New Mexico – Through economic analysis, a hypothetical 10, 25, and 50% reduction in onion bulb size from one market grade to another caused by onion thrips and Iris yellow spot (IYS) was estimated to cause a 4, 10, and 20% reduction, respectively, in marketable bulb yield; and 4, 10, and 21% reduction, respectively, in gross returns. For the US onion industry, the loss could be as large as $210 million/year. Cultivars resistant to thrips and/or IYS exhibit less or no reduction in bulb size when challenged by these pests. If the onion germplasm developed by the New Mexico onion breeding program for resistance to either/both pests can reduce one insecticide application for control of thrips, an estimated $56 to $91/acre could be saved depending on the insecticide applied. Nationally, savings could reach $13 million/year. New York – The incidence and severity of IYS were evaluated for 3 cultivars with increasing susceptibility to onion thrips, Avalon, Delgado and Bradley. Cultivars were sprayed weekly with insecticides, sprayed when thrips densities reached a threshold of 1 larva/leaf, or not sprayed with insecticides. All cultivars had 100% IYS incidence by harvest, but severity of IYS was greater in non-treated vs. treated plots from Jul. through early Aug., by which time all plots reached 100% incidence. IYS incidence and severity in plots sprayed weekly were similar to those sprayed based on the action threshold. Utah - Thirty Spanish onion cultivars were assessed for productivity and maturity, and rated for IYS. IYS symptom expression in commercial fields was very low. While all varieties showed IYS, IYS in the variety evaluations did not appear to impact bulb yield. Summer conditions were favorable for plant growth, and growers reported excellent yields with IYS appearing very late. More work on the relation between IYS incidence and bulb storage is needed. Objective 2. Investigate thrips biology and IYSV epidemiology to improve management strategies. Colorado - A 2014 survey of growers’ fields in Utah and Colorado showed that soil potassium (K) levels correlated with IYS symptom expression and IYSV incidence. A 2015 trial showed that increasing soil K from 170 to 350 ppm doubled the percentage of symptomatic plants, and increased available soil micronutrients, especially manganese (Mn). Many growers’ fields have >400 ppm K. In 2016, a field trial was conducted to identify if soil type, soil texture, and fertilizer type might influence the efficacy of using K and other nutrients to manage IYSV, by evaluating the effects of two K fertilizers and three application rates on the relationship with IYS, IYSV incidence, and onion thrips. As the rate of application of K fertilizer increased to 750 g/10 ft row, IYS severity and incidence of plants with IYSV (ELISA) increased; however, non-treated control plots had the greatest incidence of IYSV. The efficacy of Minecto-Pro insecticide in an integrated foliar management program was compared to the grower standard program with Movento (Bayer). Minecto-Pro gave comparable thrips control to the standard program. Georgia - Losses caused by IYSV in Georgia were negligible in the 2016 Vidalia onion crop. In most years, conditions are is too cool for IYSV to cause significant damage in short-day onion crops grown from September to May in southeastern Georgia. Idaho - Natural infection of Allium fistulosum, green or bunching onion, by IYSV was confirmed in Idaho. Foliar symptoms included elliptical to irregular, straw-colored, chlorotic lesions there were mostly elongate and irregular-shaped. The N-gene sequence was 99% identical to that of an IYSV isolate from Washington (KF263486.1). New York - Early-season management of onion thrips is most effective with foliar applications of Movento. However, the number of applications (1 vs. 2) and action threshold (0.2 vs. 1 thrips/leaf) required to optimize control are unknown. Among four application frequency x action threshold combinations evaluated, two applications of Movento, the first at 1 thrips/leaf and the second a week later, reduced infestation the most and for the longest. Movento will continue to be recommended when thrips populations reach 1/leaf. Minecto Pro (abamectin + cyantraniliprole) was highly effective against onion thrips as a foliar spray at 7 or 10 fl oz/acre. Efficacy of Minecto Pro was similar to Exirel (cyantraniliprole) at 13.5 fl oz/acre, but better numerically than Agri-Mek (abamectin) at 3.5 fl oz/acre. Minecto Pro and Radiant (spinetoram) at 8 fl oz/acre provided equivalent thrips control. Minecto Pro should be available to NY growers in 2017. The ability to rescue onion crops from severe onion thrips infestation was evaluated using Exirel (13.5 and 20.5 fl oz/acre) and Radiant (6 fl oz and 10 fl oz/acre). Two population levels (4.3 and 9.1 thrips/leaf) were established, at which time each of four insecticide product x rate treatments were applied and followed with a second application a week later. Thrips infestations were controlled effectively with all four treatments when applications were made at 4.3 thrips/leaf. In contrast, only the high rate of Radiant reduced thrips populations when treatments were applied at 9.1 thrips/leaf. This is useful information for growers who encounter severe thrips infestations. A laboratory bioassay was used to assess sensitivity of 6 onion thrips populations in NY to Radiant, of which 1 (from a farm near Sodus, NY) was more susceptible than the others. Other populations were less susceptible and had greater variability in susceptibility to Radiant, suggesting the populations contain susceptible and resistant individuals. Research is needed to determine why some thrips populations are more susceptible, and the mechanism(s) of resistance. Combinations of N fertilizer and insecticide were evaluated for thrips control in onion 3 cultivars differing in susceptibility to thrips. Nitrogen was applied at planting at 60, 90, and 125 lbs/acre. Insecticide regimes included a weekly spray program (standard), a program based on 1 larva/leaf (action threshold), and non-treated plots. Regardless of cultivar, N had no effect on larval thrips densities or bulb yields. Across cultivars, the standard and action threshold programs provided equivalent thrips control and reduced the population 60-81% compared to control plots. Standard and action threshold program plots had similar yields and yielded 10-54% greater than control plots. However, the action threshold program averaged 33-50% fewer insecticide applications than the standard program. Results indicated growers can reduce the number of insecticide applications and N rate at planting without compromising yield or thrips control within the range of treatments evaluated. Oregon – Onion thrips and IYSV management were evaluated in field trials with 36 insecticide regimes. Product recommendations included using Movento at the start of programs. However, when management needs to begin by May, delaying use of Movento by 1-2 weeks can improve management of peak thrips populations at the end of June and early July. Utah – Onion thrips and IYSV were evaluated in a N-by-crop rotation trial from Jun. to Sep. Thrips densities (averaged across treatments) were low in Jun. (10/plant), moderate in Jul. (45/plant), and high in late Aug. (102/plant). Onion plants grown with low N (140 lb/A) had fewer thrips/plant than plants grown with high N (330 lb/A). Onion yields were similar in low and high N plots. IYSV was detected in early Aug. and increased dramatically thereafter. IYS incidence by late Aug. was very high with some fields at 60%. Sustainable production occurs when crop inputs (variety selection, plant nutrition, irrigation management, and pest control), onion thrips, and IYSV are managed properly. Growers in Utah reported little difficulty controlling thrips and noted IYS severity varied greatly from low to moderately high incidence in 2016. Growers are using Utah State Univ. research on improving N levels, doing a better job of keeping field borders weed-free, and changing crop rotation practices to better manage thrips numbers and IYSV. Washington - Field plots (cv. Calibra) were established in Pasco, WA, with drip irrigation and standard grower practices, excluding thrips treatments on 9 May 2016 with two double-rows/44-inch-wide bed. Lorsban 15G (chlorpyriphos) was applied at planting and incorporated (3.7 oz./1,000-ft-row). Foliar applications were made with a tractor-mounted plot sprayer at 30 gpa and 25 psi. Sprinkler chemigation applications were made with a trailer-mounted sprayer in 0.1-inches water/application with in-line injection of insecticide. Thrips pressure was low, with no significant reduction in thrips populations with overhead chemigation of Minecto Pro, Exirel, or Agrimek. There was a numeric decrease in thrips populations with Minecto Pro and Exirel, but not with Agrimek. Foliar Radiant applications were superior to other treatments. Foliar applications of Minecto Pro and Agrimek were numerically, not statistically, better than chemigated applications. In a separate experiment, Radiant and Lannate significantly reduced thrips numbers by chemigation compared to check plots. AzaDirect applied by drip chemigation was not effective. Warrior did not provide control of thrips. Radiant was the most effective insecticide by foliar application. Movento, Exirel, Minecto Pro, Agrimek, and Lannate all provided control better than check and Warrior plots, but were not as effective as Radiant. Thrips collected weekly by deploying yellow sticky traps in three pairs of onion seed crops and bulb crops (<1 mile apart/pair) are being evaluated for thrips species and IYSV infection (PCR assays). IYSV was present in many of the Thrips tabaci samples. The data should clarify when thrips and IYSV moved from biennial seed crops to annual bulb crops, and out of bulb crops in the fall. To date, >95% of the thrips were T. tabaci. Objective 3.  Investigate the biology, ecology and epidemiology of other pathogens to improve management strategies. Colorado - A 2-year study to investigate efficacy of symbiotic arbuscular mycorrhizal fungi (AMF) in onions was completed. The objectives were to determine if AMF were present in four commercial onion fields under two irrigation regimes, and if application of AMF at planting could have a positive effect on bulb yield and quality, and reduce soilborne disease problems. MYKE Pro Specialty Crop P (Premier Tech) was used at 3.2 viable spores/seed and placed in planter seed boxes for application in March of 2015 and 2016 at $36/acre. Stand counts were less in AMF-treated plots at three of four locations. The inoculant powder could have displaced seed in the planter cups, reducing plant populations. There was less pink root in MYKE Pro-treated plots at two of four locations compared to check plots; however, pink root severity was lower in check plots at a third location compared to MYKE Pro plots. There was no significant difference between MYKE Pro-treated or non-treated plots in bulb size or marketable yield at all locations. No economic advantage was seen to using MYKE Pro at planting. The lack of consistency in MYKE Pro efficacy on pink root suppression and onion yield could have been influenced by high levels of soil P and/or fungicide-treated seed that can inhibit AMF root colonization.  In 2016, efficacy of the bio-pesticide Melocon, applied at 4 lb/A prior to planting, on plant parasitic nematodes in commercially grown onions was investigated. There were no differences in onion stands, nematode and thrips populations, pink root severity, and bulb size or marketable yield for Melocon vs. check plots. Limited rainfall and irrigation early in the season possibly limited nematode/Melocon interactions, and severe pink root infection could have displaced nematode feeding and/or infection of onion roots, masking potential Melocon activity. Georgia – In the past, center rot (Pantoea ananatis) has been observed after seeding (~Sep. 1) of onion beds until the end of October. In 2015, center rot progressed in onion transplants until the end of Dec., extending the window of occurrence by 8 weeks. This effect was likely due to higher than normal temperatures. Mean monthly high temperature in Nov. and Dec. were not significantly different from the mean monthly high in Mar., and the mean monthly lows were greater in Nov. and Dec. 2015 than the 5-year mean monthly low in Mar., when center rot typically begins developing again. Studies on genetic diversity of P. ananatis indicated two broad groups of the pathogen. One is diverse in terms of sources from which the bacterium was isolated (weeds, seeds, thrips, and diseased onion plants). The other was isolated predominately from diseased onion plants or seed. A host range study on five members of the Alliaceae indicated onion was susceptible to all strains of P. ananatis tested. Strains were less virulent on leek, but virulent strains tended to be more virulent on leek than other hosts tested. Epiphytic populations of P. ananatis studied on leaves of Florida pusley (Richardia scabra) under wet-dry periods of various durations indicated the bacterium survives best during periods of prolonged leaf wetness at 21°C. The weed might serve as a primary source of inoculum for center rot epidemics in Georgia. In another study, several sweet onion varieties were used to assess effects of timing of infection. Varieties 1518 and 1407 had lower incidence of bulb rot compared to Pirate, Sweet Harvest, and Granex. Bulbs were more susceptible to infection when inoculation occurred at bulb initiation vs. at first leaf senescence or bulb swelling. A transcriptome analysis was conducted on bulbs with different copper:iron (Cu:Fe) ratios as this was reported to affect onion resistance/susceptibility to sour skin (Burkholderia cepacia). In general, mRNA transcripts involved in the systemic acquired resistance (SAR) pathway were up-regulated in bulbs with a high Cu:Fe, whereas only one mRNA transcript was up-regulated in bulbs with a low Cu:Fe. In contrast, all mRNA transcripts were down-regulated in bulbs with a low Cu:Fe and none was down-regulated in bulbs with a high Cu:Fe. Affected mRNA transcripts included B2, bark storage protein, phototropin 1A, serine/threonine kinases, snakin-2, pathogenesis related protein 1 (PR1), and other proteins associated with SAR. In addition, an effect of cropping history not related to nutrient composition of the bulb was observed. Onion bulbs harvested from areas previously seeded to pearl millet tended to have more mRNA transcripts related to SAR up-regulation than bulbs in soil with other rotation crops. New Mexico - Seeds of original, intermediate, and advanced Fusarium basal rot (FBR)-selected populations and resistant and susceptible check cultivars were evaluated for resistance to FBR. The resistant and susceptible entries exhibited high FBR severity and incidence. With the high rate of disease development, many selected populations did not perform well in terms of FBR severity and incidence. Selections from resistant and susceptible checks exhibited reduced disease severity and incidence compared to original populations. Inoculation of 3 x 105 spores/ml of Fusarium oxysporum f. sp. cepae on a cut basal plate was very effective at causing FBR in most bulbs. Selections were made for FBR-resistant bulbs using this method. In separate studies, a reduction in FBR severity and incidence was observed when inoculum concentration was reduced to 3 x 103 spores/ml. If the basal plate was not cut prior to inoculation, FBR incidence and severity were minimal compared to cut bulbs. Additional modifications to inoculation and incubation procedures will be made to mimic natural infection. In addition, seed produced from FBR-resistant selections made in 2015 from 33 germplasm lines will be used for further evaluations to ascertain progress for resistance to FBR. New York - New York research has shown that Bravo (chlorothalonil) provides best control of Botrytis leaf blight (BLB). However, other Cornell University studies showed that, when chlorothalonil was co-applied with the insecticides Movento (spirotetromat), Agri-Mek (abamectin), and Radiant (spinetoram), control of onion thrips was reduced by 12-35%. In 2016, Bravo (3 pt/A) and Bravo (1.5 pt/A) + Scala (pyrimethanil, 9 fl oz/A) provided the best control of BLB with 84 and 81% control, respectively. However, Merivon (fluapyroxad + pyraclostrobin, 9 fl oz/A), Inspire Super (16 fl oz/A) + Rovral (1 pt/A), and Scala (9 fl oz) + Rovral (1 pt/A) were equivalent to these treatments with 85, 81, and 80% BLB control, respectively. With the exception of Quadris Top (difenaconazole + azoxystrobin), fungicides that are also effective against Stemphylium leaf blight (SLB), including Merivon (85% control), Luna Tranquility (fluopyram + pyrimethanil; 75% control), Inspire Super (difenoconazole + cyprodinil; 69.5% control), and Fontelis (penthiopyrad; 66% control) provided significant control of BLB compared with control plots. For reducing SLB progression and preventing leaf dieback, Inspire Super + Rovral performed as well as the best fungicides (Merivon, Luna Tranquility and Fontelis), while Rovral + Scala was less effective. Results will be used to make fungicide recommendations to control BLB and SLB effectively without compromising efficacy of insecticide applications targeting thrips. SLB incidence was rated using a 5-point scale (0-4), and SLB severity rated using a 7-point scale (0-6). To determine a total SLB disease score, these ratings were used in combination with estimated % leaf dieback, number of green leaves/plant, and % green foliage/plot. In plots treated with insecticides to control onion thrips, but not treated with fungicides, there was a 20-29% (significant) reduction in disease score compared with nontreated plots, indicating that thrips control is important for reducing SLB damage. In SLB Trial 1, SLB damage was best controlled using Luna Tranquility at 12 or 16 fl oz/A. SLB progression was reduced equivalently with Viathon (phosphorous acid + tebuconazole), Inspire Super, and Merivon. Aprovia Top (difenoconazole + benzovindiflupyr) significantly reduced SLB severity and kept plants healthy compared with the control plots, but numerically was not as effective as Viathon. SLB severity in plots treated with Thyme Guard (thyme oil) was not significantly different from the control plots. In SLB Trial #2, SLB control was evaluated over 7 weeks using combinations of fungicides and foliar applications of N and micronutrients.  Fungicides included Inspire Super, Luna Tranquility and Merivon, while the nitrogen and micronutrient product was ENC Elemax (Helena Chemical). Co-applications of fungicides and ENC Elemax were made during weeks 1-3 (front-loaded), weeks 3-5 (middle-loaded), weeks 5-7 (end-loaded), every other week (half), or every third week (1/3). None of the ENC Elemax foliar treatments improved SLB control or plant health beyond the fungicide program alone. In SLB Trial #3, timing of fungicides for SLB control were evaluated. Luna Tranquility was applied weekly for seven weeks starting at early bulbing, and compared with front-, middle and end-loaded program (as for SLB Trial #2), front + middle loaded (weeks 1-6), middle + end loaded (weeks 3-7), and an extended program (weeks 1-9) when two additional sprays were made after lodging. Fungicide applications towards the end of the season (end-loaded, middle + end loaded), season long, and season-long + after lodging had less SLB disease progression and severity than front-loaded and middle-loaded programs. The results indicated that highly effective fungicides should be used later in the season to control SLB. Use of SLB fungicides prior to bulbing was not evaluated. <h4>Oregon – A major portion of the Food Safety Modernization Act’s Produce Safety Rule focuses on the microbiological quality of irrigation water. Multi-year studies on the effect of contaminated irrigation water on the relative fate of generic Escherichia coli in water, in soil, and on onions during growth, curing, harvesting, and storage were completed. Drip or furrow irrigation did not appear to pose a significant risk for E. coli contamination of dry bulb onions. E. coli rapidly died-off in the soil and on onion exteriors in the field. Plastic containers did not provide added food safety value compared with wooden boxes for storage of dry bulb onions. Chlorine dioxide showed promise to remediate microbial contamination of water used in drip irrigation, if needed for compliance with water quality standards.</h4> <h4>Pennsylvania – Annual losses to bacterial diseases can range from 5-40% in PA onion crops. During 2016, efforts continued to be directed towards developing research-based management strategies for less harvest and post-harvest losses to center rot. Two replicated field trials evaluated the effect of N application timing and rate on center rot incidence and marketable yield, as preliminary data suggested applying total crop N prior to onion bulbing increased yield and reduced bacterial disease incidence. Also, low lying areas in heavily manured fields had up to 83% bacterial bulb decay incidence at harvest. A positive, quadratic relationship was found between percent foliar N at bulbing and center rot incidence at harvest. In addition, an interaction existed between N rate and application timing (half vs. full season applications) but trends were variable based on location. This may have been due to very high disease pressure at one location, suggesting a disease threshold above which augmenting N applications may not benefit disease management. Currently, there are no known public onion breeding programs targeting center rot, nor have there been many trials to evaluate susceptibility of commercial cultivars. To address this, 13 onion cultivars were evaluated in two trials for center rot susceptibility, marketability, and select horticultural characteristics. The only cultivar with lower disease incidence and severity and comparable yields to the grower standard cv. Candy was Spanish Medallion. The next step will be to evaluate this cultivar on commercial farms under diverse field settings to assess the potential to be in the Pennsylvania “Simply Sweet” program. Based on in-vitro and laboratory transplant assays, hydrogen dioxide, hydrogen peroxide with mono- and di-potassium salts of phosphorus acid, copper sulfate pentahydrate, and streptomycin sulfate were effective at reducing epiphytic bacterial populations from the surface of onion transplants. These could be important tools for reducing sources of inoculum. Many of the treatments evaluated are labeled for use in onion crops in PA; therefore, minimal adjustments would be needed to product labels to encompass pre-plant applications.</h4> Washington - Onion stunting caused by Rhizoctonia spp. is an important soilborne disease on sandy soils in the Columbia Basin of Washington and northcentral Oregon where cereal winter cover crops are planted the previous fall to prevent wind erosion of soil. The cover crop is killed with a herbicide shortly before or after onion seeding in spring. The dead cereal plants protect onion seedlings against sand-blasting, but the cover crop provides a bridge for Rhizoctonia spp. on dead cereal roots to colonize onion roots, causing onion stunting. To determine the effect of herbicide application to reduce this green bridge, three glyphosate application timing intervals preceding onion planting were evaluated. As the interval between herbicide application and onion planting increased from 3 to 27 days, the number of patches of stunted onion plants decreased by ≥55%, total area of stunted patches decreased by 54-63%, and patch severity decreased by 59-65%. Increasing the interval between herbicide application to the cover crop and onion planting is a practical strategy to avoid onion stunting. The effects of four commercial AMF products on onion growth were evaluated in a growth chamber trial for onion root colonization by AMF, and shoot height and dry weight: i) BioTerra Plus (Plant Health LLC); ii) MycoApply Ultrafine Endo (Mycorrhizal Applications, Inc.); iii) Mykos Gold Granular (Reforestation Technologies Inc.); and iv) MykePro Granular (PremierTech Horticulture). Onions in soil amended with Mykos Gold Granular were taller, had greater shoot dry weight, were colonized extensively by AMF (82.2%), and had significantly greater foliar K, total N, Mg, S, Fe, and B compared to plants in control soil without AMF treatment. Mykos Gold Granular was the only product that consistently improved onion growth and AMF root colonization, warranting evaluation under field conditions. Additional trials with AMF products as seed treatments, with or without fungicide seed treatments, revealed that the liquid formulation of Mykos Gold did not lead to onion root colonization by AMF. Fungicide seed treatments commonly used by onion growers can inhibit AMF colonization of roots. In 2016, five onion trials were completed in grower-cooperator fields in the Columbia Basin to evaluate the potential use of AMF inoculants in direct-seeded onion crops for enhancing production by increasing P use efficiency, reducing severity of soilborne pathogens, and promoting onion growth. Results to date indicate AMF treatments generally did not improve stand, bulb yield, pink root control, or foliar nutrient content significantly. However, high levels of P in the fields may have negated potential benefits of AMF. Trials are planned to evaluate potential impacts of soil P levels on AMF colonization of onion roots to assess the importance of modifying soil fertility practices in order to benefit from AMF inoculants. Objective 4. Facilitate interaction and information transfer between W2008 participants, the onion industry and other stakeholders. Colorado – Outputs of this work were presented at multiple meetings in Colorado and out-of-state. The information will be used by Colorado and national onion industries, growers, seed company breeders and pathologists, and integrated pest management specialists to select more effective management strategies including promotion of varieties less susceptible to thrips. Georgia - The annual meeting of the National Onion Assoc. and biennial meeting of the National Allium Research Conf. were in Savannah, GA on 30 Nov. – 3 Dec. 2016, and attended by >300 people associated with the onion industry, including growers and other stakeholders. There were 53 oral paper and poster presentations and a tour of the Vidalia onion industry. New York - Onion growers from around New York who had an opportunity to follow the Cornell Onion Thrips Management Program stated they: 1) found action thresholds to be useful, 2) reduced the number of insecticide sprays targeting thrips by 2 to 3/field, 3) saved an average  $50/acre, 4) had excellent thrips control, 5) maintained high bulb yields, and 6) did not appear to have difficulty controlling thrips with Radiant. About 75% of onion growers in NY adopted all or part of the program, saving about $350,000/year. In the hot and dry 2016 season, 10 growers participated in the Cornell Cooperative Extension Vegetable Program Onion Research Scouting Program (collaboration with Cornell Onion Thrips Management Program) and saw that BLB and downy mildew (DM) pressure were very low and, thus, gained confidence to follow the recommendations to skip fungicide applications for these diseases. The farmers reduced fungicide sprays by 83 and 74% to an average of 1.3 and 3.7 times for BLB and DM, respectively, and total costs by 58% to only $50/acre. Results were presented at meetings throughout NY and beyond. Oregon – In a new area-wide monitoring program, Treasure Valley growers received weekly reports of thrips abundance and IYSV incidence collected from commercial fields throughout the valley. This information enabled growers to better assess risks of thrips and IYSV in their growing regions. <h4>Pennsylvania – Research results were disseminated at local and regional vegetable grower meetings in-state and internationally. Results were also disseminated throughout the season through one-on-one interactions with growers.</h4> Utah – Utah State University, in cooperation with the Utah Onion Assoc., hosted: Annual winter onion meetings (54 attended) in Feb. 2016 in Brigham City, UT; and a summer field tour (52 attended) in Aug. 2016. Two presentations were made at the joint NOA/NARC meetings describing Utah based onion research, and the Utah State report given at the W2008 meeting on 1-3 Dec. in Savannah, GA. Washington – The Washington State Univ. Onion Field Day in 2016 was attended by~100 growers and other stakeholders who viewed replicate plots of 50 cultivars, with presentations made by researchers. In Feb. 2016, onion bulbs in storage were evaluated for 55 cultivars from the 2015 WSU Onion Cultivar Trial to assess storage quality and diseases. Numerous presentations were given in 2016 (see Publication and Field Days below), and many onion samples diagnosed with accompanying management recommendations.

Publications

(See attached file for complete listing of abstracts, reports, and presentations.) Asselin, J.E., J.M. Bonasera, and S.V. Beer. 2016. PCR Primers for detection of Pantoea ananatis, Burkholderia spp., and Enterobacter sp. from onion. Plant Disease 100:1-11. Bartolo, M.E., and K.J. Tanabe. 2015. Onion variety trial. Pp. 16-18 in: Arkansas Valley Res. Center 2010 Reports, CO State Univ. Ag. Expt. Station Tech. Rep. TR15-11. Drost, D., C. Cannon, D. Alston, M. Murray, C. Nischwitz, M. Pace, B. Bunn, B. Hunter, and T. Beddes. 2016. Utah Vegetable Production and Pest Management Guide (206 pp). Utah State University Extension, Logan, UT. <a href="http://utahpests.usu.edu/IPM/files/uploads/Publications/UT-veg-guide-2016.pdf">http://utahpests.usu.edu/IPM/files/uploads/Publications/UT-veg-guide-2016.pdf</a> du Toit, L.J., Waters, T., and Reitz, S. 2016. Internal dry scale and associated bulb rots of onion. Extension Bulletin PNW686. Dutta, B., R. Gitaitis, A. Barman, U. Avci, K. Marasigan, and R. Srinivasan. 2016. Interactions between Frankliniella fusca and Pantoea ananatis in the center rot epidemic of onion (Allium cepa). Phytopathology 106:956-962. Gourd, T.G. 2016. Summary of the Northern Colorado Onion Variety Trials for 2016. 2016 Rep. Colorado State Univ. Extension Adams Co. Pp.1-4. Hay, F.S., D. Strickland, E. Maloney, and C.A. Hoepting. 2016. Anthracnose of onion caused by Colletotrichum coccodes in New York. Plant Disease 100:2171. Hoepting, C.A. 2016. Efficacy of fungicide treatments for control of downy mildew on onion, 2015.  Plant. Dis. Manag. Rep. 10:V119. Hoepting, C.A. 2016. Efficacy of fungicide treatments for control of Stemphylium leaf blight on onion, 2015.  Plant Dis. Manag. Rep. 10:V121. Hoepting, C.A. 2016. Improved efficacy of fungicide Scala SC for control of Stemphylium leaf blight on onion, 2015. Plant. Dis. Manag. Rep. 10:V117. Hoepting, C.A. 2016. Managing Stemphylium leaf blight: Spray by number to prevent fungicide resistance. Onion World  32(6):6-10. Jacobson, A.L., B.A. Nault, E.L. Vargo, and G.G. Kennedy. 2016. Restricted gene flow among lineages of Thrips tabaci supports genetic divergence among cryptic species groups. PLoS ONE 11(9): e0163882. <a href="http://dx.doi.org/10.1371/journal.pone.0163882">http://dx.doi.org/10.1371/journal.pone.0163882</a>. Knerr, J.A., Paulitz, T.C., and du Toit, L.J. 2016. Effects of commercial arbuscular mycorrhizae fungi (AMF) products on onion in a growth chamber study, 2015. Plant Dis. Manage. Rep. 10:V098. Moloto, V.M., Goszczynska, T., du Toit, L.J., and Coutinho, T.A. 2016. A new pathovar of Pseudomonas syringae, pathovar allii, isolated from onion plants exhibiting symptoms of blight. Europ. J. Plant Pathol. 146: doi:10.1007/s10658-016-1028-1. Nault, B.A. 2016. Medicating onions for thrips infestations: New remedies to consider. Onion World  32(3): 8-13. Nault, B.A., and A.S. Huseth. 2016. Evaluating an action-threshold based insecticide program on onion cultivars varying in resistance to onion thrips (Thysanoptera: Thripidae). J. Econ. Entomol. 109(4):1772-1778. Reitz, S.R., C.S. Cramer, C.C. Shock, E.B.G. Feibert, A. Rivera, and L. Saunders. 2016. Evaluation of new onion lines for resistance to onion thrips and Iris yellow spot virus. Pp. 170-174, In: 2015 Malheur Exp. Stn Annu. Rep. OR State Univ. Agric. Expt. Stn. Circ. 156. Rinehold, J., Bell, N., Waters, T.D., and McGrath, D. 2016. Vegetable insect pests. In: 2015 Pacific Northwest Insect Management Handbook, Craig Hollingsworth, Editor. Oregon State University, Corvallis, OR. Sharma-Poudyal, D., Paulitz, T.C., and du Toit, L.J. 2016. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Plant Dis. 100:1474-1481. Shock, C.C., S.R. Reitz, R.A. Roncarati, H. Kreeft, B.M. Shock, and J. Klauzer. 2016. Drip vs. furrow irrigation in the delivery of Escherichia coli to onions. Appl. Eng. Agric. 32:235-244. Smith, E.A. 2016. Patterns of dispersal activity of onion thrips, Thrips tabaci Lindeman, in onion ecosystems. Cornell University, PhD dissertation. Pp. 131. Smith, E. A., E. J. Shields, and B. A. Nault. 2016. Onion thrips colonization of onion fields bordering crop and non-crop habitats in muck cropping systems. J. Appl. Entomol.: in press. Smith, E. A., E. J. Shields, and B. A. Nault. 2016. Impact of abiotic factors on onion thrips (Thysanoptera:  Thripidae) aerial dispersal in an onion ecosystem. Environ. Entomol. 45:1115- 1122. Tabassum, A., Reitz, S., Rogers, P., and Pappu, H. R. 2016. First report of Iris yellow spot virus infecting green onion (Allium fistulosum) in the USA. Plant Dis. 100:2539. Wohleb, C.H., and Waters T.D. 2016. Yield, quality, and storage characteristics of onion cultivars in the Columbia Basin of Washington. HortTech. 26(2):230-243. Zaid, A.M., J.E. Asselin, and S.V. Beer. 2016. Detection of Burkholderia cepacia in onion planting materials and onion seeds.  Chapter 22 in: Manual on Detection of Plant Pathogenic Bacteria in Seed and Planting Material, 2nd Ed. M. Fatmi and N. W. Schaad, eds. American Phytopathological Society. St. Paul, MN. In press.

Impact Statements

In Washington State, results from the thrips insecticide efficacy results were shared at the WSU Onion Field Day on August 25, 2016, several grower meetings, telephone conversations with numerous producers, and by a written report sent to onion producers. Using the most effective insecticides will improve their yields and reduce the incidence of IYSV, therefore improving yield, quality, and profitability of producers. An impact report by Washington State University (http://ext100.wsu.edu/impact/improving-insect-management-in-dry-bulb-onions-in-the-columbia-basin/) cites the importance of this work and how widely adopted these practices are by Washington Onion Producers. The report indicates that adoption of new IPM strategies for onion thrips could increase the Washington onion crop value by > $13 million annually. As a result of the successful impacts of university researchers and extension personnel on the onion industry in the Columbia Basin, the Columbia Basin Onion Research Commission was formed in 2016 with voluntary contributions by onion growers of $5/acre of onion crops. If all growers participate, this will generate ~$100,000/year in research funding to support regional onion growers.

Date of Annual Report: 01/02/2018

Report Information

Annual Meeting Dates: 09/30/2017 - 09/30/2017
Period the Report Covers: 10/01/2016 - 09/30/2017

Participants

Beth Gugino The Pennsylvania State University bkgugino@psu.edu
Tim Waters Washington State University twaters@wsu.edu
Steven Beer Cornell svb1@cornell.edu
Rick Jones Seminis Vegetable Seed rick.jones@monsanto.com
Jeremiah Dung Oregon State University Jeremiah.dung@oregonstate.edu
Claudia Nischwitz Utah State University claudia.nischwitz@usu.edu
Kerrick Bauman L & L Ag Production kerrick@llfarms.com
Filippo Rimi Crookham Company filippor@crookham.com
David Whitwood Crookham Company davew@cookham.com
Steve Loring New Mexico State University (AA) sloring@nmsu.edu
Manzeal Khanal Texas A&M University manzeal.khanal@ag.tamu.edu
Megan Lewien Bayer-Nunhems Vegetable Seed megan.lewien@bayer.com
Katie Goldenhar Syngenta Canada katie.goldenhar@syngenta.com
Beth Brisco Michigan State University briscoel@msu.edu
Ben Werling Michigan State University werlingb@msu.edu
Kristin Oomen Bejo Seeds, Inc. k.oomen@bejoseeds.com
Alex Putman UC Riverside aiputman@ucr.edu
Subas Malla Texas A&M University subas.malla@ag.tamu.edu
Travis Cranmer OMAFRA travis.cranmer@ontario.ca
Bhabesh Dutta University of Georgia bhabesh@uga.edu
Robert T. Sakata Sakata Farms rtsakata@aol.com
Joe LaForest Southern IPM Center laforest@uga.edu
Christy Hoepting Cornell Cooperative Extension cah59@cornell.edu
Brian Nault Cornell University ban6@cornell.edu
Ashley Leach Cornell University al2282@cornell.edu
Chris Cramer New Mexico State University cscramer@nmsu.edu
Mark Uchanski Colorado State University mark.uchanski@colostate.edu
Lindsey du Toit Washington State University dutoit@wsu.edu
David Brink Brink Muck Farms brinkmuchfarms@att.net
Kevin Vander Kooi University of Guelph kvander@uoguelph.ca
Zach Telfer University of Guelph ztelfer@uoguelph.ca
Glenn Vogel Vogel Produce, Inc. vogelproduce@netmail.com
Scott Vogel Vogel Produce, Inc. scottvogel@gmail.com

Participants Attachment:

W2008 3008 ANNUAL REPORT 2017 FINAL.docx

Brief Summary of Minutes

Chair Lindsey du Toit called the meeting to order at 8:30 am.

Special thanks to our meeting sponsors: Robert Sakata, Rick Jones representing Seminis/Monsanto, Kristin Oomen representing Bejo Seeds, Wayne Mininger representing the National Onion Association, Dave Whitworth representing Crookham Seed Co., Megan Lewien and Juan Carlos Brevis representing Nunhems/Bayer, Dave Brink of Brink Muck Farms in Grant, MI, and Steve Loring, NMSU.

Update from Steve Loring, Administrative Advisor:

This is a joint meeting that represents the conclusion of the W-2008 project, which ended in September 2017, and the start of the new project, W-3008.

The termination report for W-2008 is due this year with a particular emphasis on impacts. Frame the impacts around their importance to the onion industry. These are used to justify continued funding. Steve shared handouts about what makes a good impact statement (see attachments).

Steve is looking for good photographs that can be included in the report. We will likely be chosen for a national impact statement – Steve said “Help me tell your story”.

Nomination for multistate award of excellence – 1^st step is review by the regional associations and then 2^nd step is being put forward for the national award. Steve was encouraged to nominate our project again this year. The 3-page nomination form emphasizes outputs, outcomes and impacts; added value and synergistic activities – how working together and with industry has benefited the project; leveraged funding – include specific examples – What have we done, what is the impact and how have we leveraged funding. The nominations are due to the western regional association by Feb 28^th.

We have 30 days from this meeting to get the termination report submitted.

Other notes: Onionbusiness.com has a newsletter that might be of interest to this group. A writeup of this meeting will be by Kerrick Bauman shortly after this meeting.

Organizational and Planning Items

Onion research & extension needs, proposals (USDA SCRI, others)

Pappu et al. are proceeding with a USDA NIFA SCRI proposal – this is their 3^rd submission attempt – Objectives include of onion thrips, IYSV and white rot management

du Toit et al. are preparing a USDA NIFA SCRI proposal with a focus on bacterial diseases. The pre-proposal was submitted the week of this meeting.

Alliumnet website – Joe LaForest and Bhabesh Dutta (want to launch at beginning of 2018)

Southern IPM center has a focused on technology in the southern regions; however, the center will support national efforts when possible.

Southern IPM center will pick up the support and customization of the Alliumnet website but the site must have a purpose and/or well-articulated objectives.

com is the old site; http://alliumnet.bugwoodcloud.org is the new site – provides a list research and extension specialists working on pests and diseases; focuses on collaboration among research, extension and industry; this is not currently a venue for growers to find management information.

Project information will be pulled directly from the NIMSS site for the W-3008.

What’s changing as a result of support from Southern IPM Center:

Site is not a content management network – multiple people can add content using a web browser

Site navigation – focus on Projects, meetings, resources

Mobile tablet and desktop responsive

Google analytics added

Again it will have information obtained from the NIMISS and PMSP/CP websites

Questions

Who is the current audience? Are the message and purpose acceptable? Changes needed?

Who needs/wants access to edit?

Call for content

2012/2010 NARC Proceedings are missing

2018 NARC information

Old WERA 1008/W-2008 information could be added, including minutes of the annual meetings

Suggestions? Please contact Bhabesh and Joe with ideas/recommendations.

Election of new officers, future annual meeting locations, dates, etc.

Nomination for Secretary – Bhabesh Dutta was nominated last year and agreed to be Secretary elect. He confirmed his willingness to serve as the next secretary so the membership voted and he was approved as the 2018 Secretary.

W-3008 meeting in 2018

We could combine this meeting with one of the NOA meetings in 2018: July 18 to 21 in Bakerfield, CA or Nov 28-Dec 2 in Hawaii? The group decided against the latter option due to cost, and the former option because it’s too soon after this meeting.

The 2018 W-3008 meeting will be held in conjunction with the Pacific Northwest Vegetable Association Annual Convention & Trade Show the week before Thanksgiving (Nov. 14-15) in Pasco or Kennewick, WA – our W-3008 meeting will be on Tues., Nov. 13^th, before the PNVA conference. Some of the meeting participants can then be invited to speak in the onion and other vegetable sessions at the PNVA meeting, similar to many attendees of this year’s W-3008 meeting speaking at the Great Lakes Expo.

The 2019 meeting will be held in conjunction with the International Allium meeting in Madison, WI in July.

2018 officers:

Chair: Christy Hoepting, Cornell University (responsible for chairing the 2018 W-3008 Annual Meeting)

Vice-Chair: Beth Gugino, Pennsylvania State University (responsible for writing/submitting the 2018 annual project report)

Secretary: Bhabesh Dutta, University of Georgia (responsible for writing/submitting the 2018 annual meeting minutes)

Past-Chair: Lindsey du Toit, Washington State University

Lindsey du Toit adjourned the meeting at 5:00 pm.

Minutes Attachment:

W2008 3008 ANNUAL REPORT 2017 FINAL.docx

Accomplishments

California – Bob Ehn (unable to attend) <ul> <li>Bob Ehn shared that downy mildew was the main problem in southern CA along with some bacterial issues this past winter.</li> </ul> Colorado - Mark Uchanski (Colorado State University) <ul> <li>Also presenting on behalf of Mike Bartolo and Thad Gourd</li> <li>They are evaluating chemistries for control of Xanthomonas leaf blight and other bacterial issues in Colorado using copper compounds, Tanos and Fontelis.</li> <li>Onion variety trial with 42 cultivars evaluated – trials are currently in storage for evaluation.</li> <li>2017 Field conditions – more precipitation than usual; large hail storm on 10 August caused significant damage and resulted in field culls and few storable onions.</li> <li>Management strategies for IYSV: Managing potassium fertilizer – Does higher soil K mean more IYSV (iris yellow spot virus) symptom expression – observing increased symptomology under higher potassium in the field trial.</li> <ul> <li>In a field trial they applied and incorporated high rates of potassium but did not see a significant effect of this treatment on yield</li> <li>2016 IYSV incidence: ELISA vs. visual symptoms of iris yellow spot (IYS) correlated well. Observed some relationship between soil K level and IYSV; however, in 2017 IYS was very limited in occurrence – not sure why there has been a trend towards lower incidence in the field. In an attempt to increase disease pressure, they even placed symptomatic bulbs (probably loaded with thrips) in the field.</li> </ul> <li>Thad Gourd conducted a cultivar trial to evaluate thrips populations, Fusarium basal rot, pink root and onion maturity; very low incidences of IYS were observed.</li> <ul> <li>Evaluation of MeloCon (OMRI registered biological nematicide) on onion – did not see any significant differences but nematode pressure was very low in the field this year (farmer grows onions once every 4 years and does not fumigate).</li> </ul> <li>Proposed mitigations for all copper compounds (refer to the email sent out by the Environmental Protection Agency, and forwarded to many members of the W-3008 by Wayne Mininger from the National Onion Association) – the comment period closed on Nov 22 – EPA proposing reducing the total amount of copper that can be applied to onion crops 6 to 5 lb a.i./year</li> <ul> <li>How does this impact production?</li> <ul> <li>Ontario growers are not using a lot of copper; however, drip and furrow irrigation, which are the predominant types of irrigation in the Treasure Valley of OR/ID, might not be as conducive to bacterial diseases as center pivot irrigation, due to the differences in crop microclimate under different irrigation systems.</li> <li>Robert Sakata – Colorado – growers only use copper when there is a storm; only ½ of the CO acreage is overhead irrigated, and when they use drip irrigation, they only use 3 lines on a bed to encourage air circulation and lower relative humidity; CO onion crops in the front range received 15 in. of rain this season; they had ideal onion growing weather so they anticipate a good storage season for 2017-18.</li> </ul> </ul> </ul> Pennsylvania – Beth Gugino (The Pennsylvania State University) <ul> <li>Losses due to bacterial diseases were minimal this past season and there was an estimated 5% loss due to allium leafminer.</li> <li>Trials evaluating the effect of nitrogen fertilizer application rate on center rot incidence and severity; alternative plastic mulch trial and on-farm demonstration trials, cultivar trials comparing Candy (commercial standard) with Spanish Medallion (3 on-farm and 1 research trial), and a product efficacy trial in which Companion numerically (but not statistically) reduced center rot incidence in the inoculated subplots.</li> <li>Allium leafminer research is being conducted by Shelby Fleischer et al.</li> <ul> <li>The pest was confirmed initially in southeastern, and now is in much of the eastern half of Pennsylvania as well as NY, NJ and MD. USDA APHIS PPQ is unlikely to invoke action.</li> <li>The first report will be published in the Journal of Integrated Pest Management and the common name allium leafminer is now recognized by the Entomological Society of America.</li> <li>Symptoms include a line of oviposition marks on the leaves as well as serpentine mines. The larvae burrow down into the bulb and pupate. There are two flights a year, in spring and fall.</li> <li>All alliums are susceptible.</li> <li>Long-distance transport on planting material is a potential concern.</li> <li>The Fleischer lab was able to rear a colony in the lab which is promising for conducting future research.</li> <li>Future research includes comparing infestation levels among different allium hosts and cultivars; evaluating planting dates for bunching onions; and conducting insecticide efficacy trials.</li> </ul> </ul> Georgia - Bhabesh Dutta (University of Georgia) <ul> <li>2017 was a good production year – the estimated crop is valued at $145 to $150 million which represents an $8 M increase – it was a warm winter so the onions grew faster and many crops escaped disease.</li> <li>Bhabesh covered the results of fungicide trials and recommendations for growers</li> <li>Botrytis leaf blight (BLB) - #1 fungal disease on Vidalia onions</li> <ul> <li>Ghost spots observed when there is significant rainfall, high humidity and temperatures of 50 to 75°F.</li> <li>Growers start spraying in mid-February/early March so the crop is often left unprotected from November to February</li> <li>Could one spray of Fontelis (overhead drench) one week after transplanting on top of the typical last season fungicide program improve management?</li> <li>A single overhead drench application across all treatments significantly reduced the severity of BLB. In addition, a significant yield increase for both cultivars (Vidora and Pirate) was observed in plots treated with Fontelis.</li> <li>The new recommendation for onion growers is an early season application of a SDHI or Fungicide Resistance Action Committee (FRAC) Group 7 fungicide (Endura, Fontelis or Merivon) a week to 10 days after transplanting, followed by a Pristine/Bravo/Manzate rotation until mid-February, and then rotation with single-site mode of action fungicides (Inspire Super, Scala, Rovral or Omega 500).</li> <li>Discussion ensured over whether the Fontelis application might be affecting soilborne pathogen populations which, in turn, could be affecting severity of BLB?</li> </ul> <li>Other diseases they observed include Fusarium basal rot, yellow bud (occasionally seen), and sour skin (but limited incidence in 2017). Downy mildew was last reported in 2012. Purple blotch and Stemphylium leaf blight were a moderate issue.</li> <li>Center rot – three species of Pantoea cause this disease; sources of inoculum include weeds (only for ananatis) and seed; the bacteria are also transmitted by the onion thrips and tobacco thrips.</li> <ul> <li>Which onion growth stage is most susceptible to bulb infection by ananatis? Seedling, true leaf, etc.</li> <ul> <li>Infection of onion plants at the first true-leaf stage, bulb initiation and bulb swelling were evaluated by cutting the leaf tip and inoculating the cut surface</li> <li>They observed a significant effect of plant growth stage and variety; all three stages were susceptible; however among them 1st leaf senescence stage was most susceptible.</li> <li>Can we protect those specific growth stages using bactericide products, and how does thrips population influence this? Greenhouse experiments were conducted, demonstrating that thrips infestation had a significant effect on center rot development.</li> <ul> <li>In the absence of thrips, the application of bactericide products at different growth stages influenced severity of center rot. Kocide 3000 had the most significant effect, but when thrips were present in the trials, no product was effective. (30 thrips and 10 plants per cage were evaluated – 3 thrips per plant has been established as the threshold for center rot).</li> </ul> <li>Commercial onion field trial – inoculation of onion plants with center rot pathogens at the bulb initiation stage resulted in similar differences in bactericide efficacy as the greenhouse trials; also at the bulb swelling stage. When all growth stages were treated to limit thrips feeding injury, similar statistical differences were observed among the bactericide treatments, but the differences were not significant when plants were not sprayed for thrips.</li> </ul> <li>Observed significantly higher marketable yields for Kocide and Kocide + Actigard treatments when they were applied at either bulb initiation or bulb swelling.</li> </ul> </ul> Michigan – Beth Brisco representing Mary Hausbeck (Michigan State University) <ul> <li>Evaluating the interaction between bacterial foliar diseases and onion thrips – Protecting onions from thrips damage significantly reduced disease severity; they evaluated applications with and without insecticides/surfactants, etc.</li> <li>They are also evaluating sources of bacterial inoculum – weed sampling and seed sampling – and have isolated suspect bacteria</li> <li>Evaluating nitrogen fertility effects on bacterial disease incidence and severity</li> <li>Growers were more interested in Stemphylium leaf blight than bacterial diseases this season because conditions were not highly conducive to bacterial diseases</li> <li>Other trials are in progress:</li> <li>Pink root cultivar trials over 3 years – highly variable results across years; penthiopyrad (Fontelis) was significantly better at reducing pink root severity; pathogen diversity studies – they did not detect variability in the pathogen population from samples collected across MI</li> <li>Bacterial diseases – survey of foliar diseases; there were differences in cultivar susceptibility depending on the pathogen; they also are evaluating the effects of temperature, humidity and planting date on bacterial disease severity</li> <li>Ben Werling, Extension Educator with MI State University, added that the weather was good for onion production this past season although some issues with Stemphylium leaf blight were observed on one farm. In general, the drier season led to less issues with bacterial diseases.</li> </ul> New Mexico - Chris Cramer (New Mexico State University) <ul> <li>Typical year with no major pest issues; July was rainy so some growers had issues with bacterial diseases.</li> <li>Evaluating IYS incidence and severity in onion germplasm of varying leaf characteristics (HortScience,April 2017 52:527-532; doi:21273/HORTSCI11770-17) – some intermediate day germplasm is now available for seed companies to use in breeding programs.</li> <li>Evaluation of catnip for thrips control in pollination cages – Eight cages planted with the same variety, 4 with and 4 without catnip, with 3 beds per cage and each cage had a beehive; catnip grew large enough that the plant surrounded the base of the onion leaves and scapes; there were fewer thrips on the onion plants grown with catnip – however, this might have been due to the catnip or any other plant grown in a similar manner? In cages without catnip, there was significant weed pressure so the ground was not bare, confounding evaluation of the catnip.</li> <ul> <li>Also rated seed stalks for IYS on scale of 0 to 4; symptom severity was less in cages with onion and catnip vs. cages with onion plants alone.</li> <li>Seed yield – there was no difference in seed yield on a per plant basis but seed was hand harvested so lodged stalks were included in the seed yield measurement (which does not occur when seed crops are harvested mechanically).</li> </ul> </ul> New York - Christy Hoepting (Cornell University) <ul> <li>Wet slow start to the season which delayed planting; growers had invested in water management (tiling) which was beneficial this year; no heat stress; good disease year but growers did well with foliar disease management; some growers had record breaking yields; bacterial disease issues were not really a problem because of cooler temperatures.</li> <li>Onion seed treatments for onion maggot control – 90% stand loss in hot spot; Sepresto was significantly better than the untreated but still 60% loss; FarMore FI500 was the best treatment but still 30% loss (trying to figure out what factors are associated with the hot spots).</li> <li>Onion thrips management program – strategic sequence of products; evaluation of timing and sequencing (0.1 vs 1 thrip per leaf as a threshold); Movento is applied 1st and then a heavy hitter is applied 2nd in the sequence so population does not spike.</li> <li>Onion thrips nitrogen interaction trial – evaluation of two varieties with five nitrogen rates and three insecticides.</li> <li>Onion bacterial research (Steve Beer) – chlorine registered for NYS growers until 2020.</li> <li>Observed in one field that 15 to 20% of the onions were affected with a bacterial canker type system (double barreling type symptoms) – not sure the cause maybe grass herbicide damage?</li> <li>Stemphylium leaf blight – evaluating isolates for fungicide sensitivity; epidemiology study (grid sampling); post-harvest onion residue management; organic management strategies</li> <li>Observed a “spectacular purple blotch lesion show” this year.</li> <li>Foliar disease fungicide trials were conducted for Stemphylium and Botrytis leaf blight; seed and in-furrow treatment trial for smut, damping-off and pink root.</li> <li>Bare root transplant dip trial for control of pink root, Fusarium basal rot and bacterial disease.</li> <li>Continued the NYS onion research scouting program.</li> </ul> Oregon/Idaho (Treasure Valley) – nobody from this region was able to attend but Lindsey du Toit and Kerrick Bauman shared information received from growers and extension specialists in this region <ul> <li>Lindsey du Toit - Late rains during harvest season delayed harvest. Some crops were still in the ground when temperatures dropped to 25°F, with over 800 acres of the crop freezing – many of these crops were harvested and placed in storage, so there is uncertainty what is going to happen in storage.</li> <li>Kerrick Bauman – Western production is primarily of Spanish long-day cultivars; 40% of the national winter onion supply is from the Treasure Valley; 2016 was a bumper crop (warm spring so had extra leaf or two on the onion at harvest, so larger on average) – primarily a jumbo market; 1st part of December snow accumulated in the Treasure Valley (24 to 36 in.) and then the snow turned to rain causing onion storage buildings to start collapsing in January, leading to lots of loss over the winter. In addition, there was a dilemma about what to do with onions in the collapsed storage buildings – a market order was passed to require placing all the onions in landfills for pest management. Treasure Valley production (28,000 A grown for storage) is shifting increasingly from furrow irrigation to drip irrigation (80% of production is now with drip irrigation). Seed corn maggot and bulb mites were an issue as well as foliar insects such as spider mites. Production year 2017 was opposite to that of 2016 – planting was delayed from March to the end of April, beds were compacted since they had been prepared in the fall of 2016 before all the snow and rain, temperatures were hot in July with humidity in the teens, so the crop was very stressed, late, and 20 to 25% off normal yield in yellow and red cultivars, which equated to a 30 to 35% shift in onion supply this year - barely enough to cover the winter market.</li> </ul> Texas – Subas Malla (Texas A&M University) <ul> <li>Subas Malla recently started as an onion breeder in TX. There are two research stations, at Uvalde and Weslaco, in the short-day onion production areas of TX.</li> <li>Short-day onion germplasm evaluation – he evaluated 133 TAM onion lines.</li> <li>There were some issues with Stemphylium leaf blight and a little with Xanthomonas leaf blight (less significant).</li> <li>Subas is trying to learn what traits are of most interest in short-day onions to inform the selection process – selections were made for bulb firmness, single centers, and leaf and root diseases; NDVI was correlated with pink root and Stemphylium leaf blight.</li> <li>The TX onion germplasm pipeline has two lines for release: 50092 and 30300.</li> <li>Major disease issues include Stemphylium leaf blight, pink root, bacterial diseases (Xanthomonas and Pseudomonas), IYSV and downy mildew.</li> <li>A genotyping lab is being developed as part of his program and will include a BSL1 Lab and greenhouse. Subas is interested and willing to collaborate with others.</li> </ul> Utah - Claudia Nischwitz (Utah State University) <ul> <li>Yield was average in 2017; however, due to the problems reported above for the Treasure Valley, Utah growers got better prices; lots of fields were flooded for two months or more due to the major winter snow and then rain on top of frozen ground, which delayed planting. They had a few disease problems – Stemphylium leaf blight and some IYSV. They are trying to understand the mechanisms behind the relationship between potassium and IYSV. Some bulb mite issues occurred in storage and some problems in the field after planting. In addition, some growers had seed corn maggot issues. Leafminer issues started about 2 years ago.</li> </ul> Washington - Tim Waters (Washington State University) <ul> <li>Onion crop notes: Smoky conditions across most of the WA Columbia Basin growing region in late July to mid-August resulted in “high” humidity. Thrips pressure initially was low due to a cool spring, but increased later in the season. IYSV and downy mildew were more of an issue, as were Fusarium basal rot and yellow nutsedge in some crops. They have seen some major irrigation management issues – center pivot growers experiencing increased bulb bacterial disease issues. This year was the first season of research funding provided by the new Columbia Basin Onion Research Committee.</li> <li>Disease notes (bacteria) – Several growers had 30 to 40% bacterial bulb rots in red cultivars at harvest or soon after harvest, which appears to have been correlated to the high humidity in late summer caused by wildfires during late maturity of these crops; 2017 appears to be one of the worst years for bacterial rots in the Columbia Basin for some growers, so now growers are concerned about increased problems in storage. Downy mildew and Stemphylium leaf blight were only an issue in mid-August following the extended periods of wildfire smoke and high humidity, but the outbreaks were late enough to not really impact bulb yields.</li> <li>IYSV-thrips monitoring project data is being summarized – preliminary data from 2016 indicated that IYSV infection in seed crops leads to early onset of IYSV in nearby bulb crops; 1,000 A of seed crops are grown amongst 24,000 A of bulb crops, with the worst IYS problems observed in regions of the Columbia Basin with the most dense concentration of both biennial bulb and annual seed crops.</li> <li>Hanu Pappu is currently working on understanding the molecular evolutionary genomics and population structure of IYSV.</li> <li>Onion thrips – a relatively slow start to the season and then populations increased dramatically by late summer. Tim has beenobtaining less optimal control with Lannate in test plots and growers are also reporting issues. He conducted several insecticide trials – top choices are Radiant, Minecto Pro, and Lannate. Radiant provides good control when applied through center pivot irrigation.</li> <li>Onion variety trial focused on thrips this year – noticed thrips damage differences among cultivars, as in part seasons.</li> </ul> Ontario, Canada – Zach Telfer (University of Guelph) <ul> <li>Holland Marsh acreage is down to 1,000 A but profit has continued to increase; 2016 was hot and dry, but in 2017 the Marsh received double the 10-year average rainfall in addition to experiencing cool temperatures. By the end of June, over 3 in. of rain had fallen in 8 hours, which caused lots of flooding and complicated seeding. Planting was delayed by 3 weeks. Harvest usually occurs in early August for transplants but did not start until late August. Seeded onions were left in the field until the end of October, causing growers to be worried about storage quality.</li> <li>Thrips pressure was low (recommend 1 thrips/leaf threshold for insecticide applications). Because of the delayed planting, there were less issues with onion maggot. Also there is a region-wide management plan for maggot. The pest and disease field survey showed no Botrytis leaf blight (BLB) or purple blotch observed, but Stemphylium leaf blight was observed. In general, it appears Stemphylium leaf blight might be displacing BLB and purple blotch? It was also a very good year for downy mildew.</li> <li>Developed a new in-field sampling method for Stemphylium leaf blight – rank the 3 oldest leaves, with a maximum score of 6 (score 0 = no disease, 1 = ≤50% severity of symptoms, 2 = >50% severity), and then calculate a disease severity index.</li> <li>Some hypothesized that the increase in Stemphylium leaf blight prevalence and severity was correlated with use of the herbicide Chateau, but that hypothesis did not hold up in a replicated research trial.</li> <li>Evaluated the disease forecasting Botcast for BLB, but BLB not observed due to Stemphylium leaf blight being so severe. The DOWNCAST model did not predict downy mildew outbreaks in 2017 but there was a significant outbreak. DOWNCAST might work best for determining when there will not be a problem rather than predicting a problem.</li> <li>The Stemphyium leaf blight pathogen population appeared to have resistance to Luna Tranquility and Quadris Top.</li> <li>Future research includes monitoring onion insect populations (IPM); updating and examining DOWNCAST, improving Stemphylium leaf blight control/fungicide timing; evaluating Stemphylium vesicarium isolates for fungicide resistance.</li> </ul>   Other onion project reports Ashley Leach & Brian Nault – Insect management research update in New York <ul> <li>Increasing use of action threshold in managing onion thrips on New York farms</li> <ul> <li>Onion thrips go through 3 to 4 generations per season</li> <li>Improved use of action thresholds through scouting program</li> <li>They categorized the degree of adoption – completely followed, mostly followed, and did not follow – to survey the success of this program and the recommendations</li> </ul> </ul> Christy Hoepting – NY onion disease research update <ul> <li>Stemphylium leaf blight (SLB) was associated with more severe bacterial rot in onions that died prematurely</li> <ul> <li>Luna Tranquility and Merivon were most consistent for SLB management</li> <li>Confirmed resistance to of vesicarium isolates to fungicides in FRAC Group 11</li> </ul> </ul> Bhabesh Dutta – Research updates on Pantoea spp. in Georgia <ul> <li>From 1997 to 2015, collected Pantoea strains isolated from seeds, weeds, thrips, etc. in Vidalia County. In total, 50 strains were collected - 23 from onion plants, 5 from seed, 16 from weeds, 6 from thrips.</li> <li>33 were determined to be pathogenic on onion and 31 strains were ice nucleation positive; all were sensitive to copper</li> <li>Multi-locus sequence analyses (MLSA) of 6 housekeeping genes – Identified 3 onion clades, 8 clades of diverse sources and 15 unresolved strains – there was not much diversity or patterns or correlation among isolates, source of isolation and phenotypic characteristics</li> <li>REP-PCR assay was used to determine DNA fingerprint diversity – 4 clades were identified with no trends between phylogeny and pathogenic phenotypes</li> <li>Pathogenicity of the bacterial strains on onion, leek, shallot, and chive – 33 strains tested by measuring lesion length 5 days post inoculation from the point of inoculation</li> <ul> <li>Very few strains were pathogenic on chive</li> <li>A lot of diversity among strains was detected with this assay but not with the molecular assays</li> </ul> <li>Whole genome sequencing of 10 strains</li> <ul> <li>Bulb scale pathogenicity test on red scale onion – the scale develops a “clearing of red skin” demonstrating the degradation of the scale cells</li> <li>They were able to differentiate pathogenic and nonpathogenic strains using whole genome sequences</li> <li>An onion virulence region was identified in ananatis – so now they are developing primers for this region to differentiate pathogen and non-pathogenic isolates</li> </ul> <li>Pantoea stewartii indologenes</li> <ul> <li>A new set of bacterial strains was characterized that differed from known pathogens. The 16S rDNA sequence analysis of all the type strains were used to compare and differentiate these new onion strains; MLSA was conducted with 4 housekeeping genes</li> <li>Biochemically, they could not differentiate strains of ananatis and P. stewartii</li> <li>Pathogenicity tests on pearl millet – onion strains caused disease on pearl millet</li> <li>Hypothesized they are dealing with a subspecies of stewartii subsp. indologenes</li> <li>This is the 4th pathogen in the Pantoea genus that is pathogenic to onion.</li> </ul> </ul> Chris Cramer – Onion breeding update from New Mexico <ul> <li>Fusarium basil rot resistance – new inoculation technique focused on inoculating mature basil plates excised from bulbs</li> <li>Evaluating the use of saponin levels as a potential measure of resistance for screening germplasm</li> </ul> Steven Beer – Onion bacterial disease research reports <ul> <li>Sur-Chlor registered for use on onions in NY to reduce bacterial bulb decay, under a Section 24(c) - 12.5% solution approved for use in NY only.</li> </ul> Kevin van der Kooi and Zach Telfer – Onion downy mildew research in Ontario, Canada <ul> <li>Downcast and spore trapping – spore trapping early in the morning for 2 hours</li> <li>Product efficacy trial – Orondis Ultra, Dithane and Zampro were most effective, as good as the standard fungicide program</li> </ul> Beth Brisco – Stemphylium leaf blight field trials in Michigan <ul> <li>Foliar diseases typically include purple blotch and anthracnose but they now seeing Stemphylium leaf blight and bacterial leaf blight.</li> <li>Stemphylium leaf blight fungicide trial – 10 applications made on 7-day intervals – Luna Tranquility at both rates was the best of the products evaluated, along with Fontelis.</li> </ul>

Publications

Buckland, K., D. Alston, J. Reeve and C. Nischwitz.  2017.  Trap crops in onion to reduce onion thrips and Iris yellow spot virus.  Southwestern Entomologist 42(1): 73-90. http://dx.doi.org/10.3958/059.042.0108.   Cramer, C.S.  2017.  Evaluating Iris yellow spot disease incidence and severity in onion germplasm of varying leaf characteristics.  HortScience 52:527-532.   Dung, J. and R. Wilson.  2017.  In search of the next DADS: continuing research on fungicides and sclerotia germination stimulants for White Rot control.  Onion World (May/June 2017):4-6.   Dutta, B., F. Anderson, S. Smith, and R.D. Gitaitis.  2017.  Epiphytic survival of Pantoea ananatis on Richardia scabra in Georgia.  Plant Disease 101:613-618.   Henrichs, B., M.L. Derie, T.D. Waters and L.J. du Toit.  2017.  The effects of arbuscular mycorrhizal inoculants on onion root colonization and growth in field trials near Connell, WA, 2016.  Plant Disease Management Reports 11:V137.   Henrichs, B., T.D. Waters, and L.J. du Toit.  2017.  The effect of soil phosphorus levels on colonization of onion roots by arbuscular mycorrhizal fungi, 2016-2017.  Plant Disease Management Reports 11:V125.   Hoepting, C.A.  2017.  Efficacy of foliar nutrient feeding on Stemphylium leaf blight on onion, 2016.  Plant Disease Management Reports 10:V129. Doi: 10.1094/PDMR11.   Hoepting, C.A.  2017.  Efficacy of fungicide timing on Stemphylium leaf blight on onion, 2016.  Plant Disease Management Reports 10:V130. Doi: 10.1094/PDMR11.   Hoepting, C.A.  2017.  Efficacy of fungicide treatments for control of Botrytis leaf blight and Stemphylium leaf blight on onion, 2016.  Plant Disease Management Reports 10:V127. Doi: 10.1094/PDMR11.   Hoepting, C.A.  2017.  Efficacy of fungicide treatments for control of Stemphylium leaf blight on onion, 2016.  Plant Disease Management Reports 10:V128. Doi: 10.1094/PDMR11.   Johnson, W., B. Dutta, F.H. Sanders, and X. Luo.  2017.  Interactions among cultivation, weeds and a bio fungicide in organic Vidalia sweet onion.  Weed Technology 31:890-896.   Leach, A., M. Fuchs, R. Harding, R. Schmidt-Jeffris and B.A. Nault.  2017.  Transplanted onion fields host abundant dispersing viruliferous onion thrips early to mid-season for late season Iris yellow spot virus epidemics in New York.  Plant Disease (in press) <a href="https://doi.org/10.1094/PDIS-06-17-0793-RE">https://doi.org/10.1094/PDIS-06-17-0793-RE</a>.   Leach, A., S. Reiners, M. Fuchs and B.A. Nault.  2017.  Evaluating integrated pest management tactics for onion thrips and pathogens they transmit to onion.  Agriculture, Ecosystems & Environment 250: 89-101.   Mazzone, J.E.  2017.  Responding to growers’ needs: evaluation of management strategies for onion center rot, caused by Pantoea ananatis and Pantoea agglomerans.  M.S. Thesis, The Pennsylvania State University, University Park, PA, May 2017.   Moloto, V.M., T. Goszczynska, L.J. du Toit, and T.A. Coutinho.  2017.  A new pathovar of Pseudomonas syringae, pathovar allii, isolated from onion plants exhibiting symptoms of blight. Europ. J. Plant Pathol. 146:591-603.   Murray, M.K., P. Jepson, S. Reitz.  2017.  An integrated pest management strategic plan for treasure valley onions: Oregon and Idaho.  Western Region Integrated Pest Management Center. <a href="https://ipmdata.ipmcenters.org/documents/pmsps/Onion_IPMSP_June_2017.pdf">https://ipmdata.ipmcenters.org/documents/pmsps/Onion_IPMSP_June_2017.pdf</a>   Reitz, S.R.  2017.  Evolution of onion pest management in the treasure valley.  Onion World (February 2017) pp. 6-8.   Rinehold, J., N. Bell, T.D. Waters and D. McGrath.  2017.  Vegetable insect pests.  In Craig Hollingsworth (Eds.), 2015 Pacific Northwest Insect Management Handbook Corvallis, OR: Oregon State University.   Smith, E.A., E.J. Shields, and B.A. Nault.  2017.  Onion thrips colonization of onion fields bordering crop and non-crop habitats in muck cropping systems.  Journal of Applied Entomology 141(7): 574-582.   Stumpf, S., R. Gitaitis, T. Coolong, C. Riner, and B. Dutta.  2017.  Interaction of onion cultivar and growth stages on incidence of Pantoea ananatis bulb infection.  Plant Disease 101:1616-1620.   Waters, T.D. and J.K. Darner.  2017.  Thrips managment on dry bulb onions with the use of foliar insecticide applications, 2016.  Arthropod Management Tests 2017; 42 (1): tsx081. doi: 10.1093/amt/tsx081.   Zhao, X., S.R. Reitz, H. Yuan, Z. Lei, D.R. Paini, and Y. Gao.  2017.  Pesticide-mediated intraspecific competition between local and invasive thrips pests. Nature Scientific Reports. 7:40512 | DOI: 10.1038/srep40512.

Impact Statements

In Utah, more onion growers are getting soil tests done prior to planting rather than just applying a set amount of fertilizer regardless of what is present in the soil. Research by Dan Drost and Diane Alston showed that thrips populations are often higher on onions grown with high nitrogen levels and Claudia Nischwitz showed that potassium levels can affect IYSV symptom expression.