W3008: Integrated Onion Pest and Disease Management

(Multistate Research Project)

Status: Inactive/Terminating

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Annual/Termination Reports:

[01/02/2018] [01/07/2019] [09/21/2019] [04/01/2021] [04/25/2022]

Date of Annual Report: 01/02/2018

Report Information

Annual Meeting Dates: 12/04/2017 - 12/04/2017
Period the Report Covers: 12/04/2017 - 12/04/2017

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:

W3008 12-04-2017 Annual Mtg Minutes.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.

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. <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> <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. <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> <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 <ul> <li>How does this impact production? <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> </li> </ul> </li> </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. <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> </li> </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 <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> <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. <ul> <li>Which onion growth stage is most susceptible to bulb infection by ananatis? Seedling, true leaf, etc. <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. <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> <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> <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> </li> </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. <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> </li> </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 <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> </li> </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 <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> </li> </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 <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> <li>Whole genome sequencing of 10 strains <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> <li>Pantoea stewartii indologenes <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> </li> </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.

Date of Annual Report: 01/07/2019

Report Information

Annual Meeting Dates: 11/13/2018 - 11/13/2018
Period the Report Covers: 10/01/2017 - 09/30/2018

Participants

Lindsey du Toit Washington State University dutoit@wsu.edu

Bhabesh Dutta University of Georgia bhabesh@uga.edu

Rob Wilson UC ANR Intermountain REC rgwilson@ucanr.edu

Tom Twini UC Extension Fresno taturini@ucanr.edu

Subas Mall Texas A&M University Subas.malla@agtam.edu

Emma Lookabaugh Nunhems emma.lookabaugh@vegetableseeds.basf.com

Kevin Border Nunhems kevin.border@vegetableseeds.basf.com

Kerrick Bauman L & L Ag Production kerrick@llfarms.com

David Burrell National Onion Labs davidb@onionlabs.com

Michael Bartolo Colorado State University michael.bartolo@colostate.edu

Emma Locke DP Seeds emma.L.Locke@gmail.com

Chris Cramer New Mexico State Univ. cscramer@nms.edu

Beth Gugino Penn State bkgugino@psu.edu

Brenda Schroeder University of Idaho bschroeder@uidaho.edu

James Woodhall University of Idaho jwoodhall@uidaho.edu

Devon Beck Seminis devon.beck@bayer.com

Stuart Reitz Oregon State University stuart.reitz@oregonstate.edu

Tim Hanoff Bluewater thanoff@gmail.com

Hanu Pappu Washington State University hop@wsu.edu

Romania Iftikhar Washington State University rmniftikhar229@gmail.com

Benn Gross Grower bjwhb@gmail.com

Tim Waters Washington State University twaters@wsu.edu

Carrie Wohleb Washington State University cwohleb@wsu.edu

Lorin Grigg Grower lcgrigg@gmail.com

Jim Christopherson Bejo Seeds j.christopherson@biejoseeds.com

Rachel Hills Anderson Organics rachel@ao.farm

Brian Crummey Bejo Seeds b.crummey@bejoseeds.com

Darlene Maxwell Bejo Seeds d.maxwell@bejoseeds.com

Kevin Kulsh L & L Ag Production kevin@llfarms.com

Dan Drost Utah State University dan.drost@usu.edu

Ceely Will Nunhems ceely.will@vegetableseeds.basf.com

Emily Johnson Nunhems emily.johnson@vegetableseeds.basf.com

Filippo Riiel Crookham Co filippor@crookham.com

David Whitwood Crookham Co davew@crookham.com

Bob Simerly McCain Foods bob.simerly@mccain.com

Rene Emch Enza Zaden r.emch@enzazaden.com

Zeb Rehrig Enza Zaden w.rehrig@enzazaden.com

TJ Gamacle CSS Farms tyler.gamacle@cssfarms.com

Cody Nickoloff CSS Farms cody.nickoloff@cssfarms.com

Christy Hoepting Cornell Vegetable Program cah59@cornell.edu

Participants Attachment:

W3008 Annual Report Year 1 2018 final v2.docx

Brief Summary of Minutes

Chair Christy Hoepting called the meeting to order at 8:30 am.

Participants introduced themselves to the group. Steve Loring, Administrative Adviser, joined us via phone assisted by Tim Waters. He congratulated us on the 2018 Excellence in Multistate Research-Western Region Award. Also, reminded us that the annual report, list of the W3008 attendees and minutes of the meetings are due within 60 days of this meeting. The report should be emailed to Steve and he will upload it into the NMISS system.

State reports and other project updates:

Participating members made presentations representing California (Tom Turini, Rob Wilson), Georgia (Bhabesh Dutta), Pennsylvania (Beth Gugino), Colorado (Mike Bortolo), Utah (Dan Drost), New Mexico (Chris Cramer), Texas (Subas Malla), Idaho (James Woodhall), Oregon (Stuart Reitz), Washington (Tim Waters), and New York (Christy Hoepting).

Organizational and Planning Items

Onion research and extension needs: Pink root USDA AFRI project was submitted by Subas Malla, TAMU. Other interests shared by participants include: Fusarium basal rot, tolerance to soil salinity, economics on marketing (“market blight”), importance of soil health, precision/digital ag technology in onion integrating IPM, variety development and labor issues as well as exploring non-traditional growing regions to compensate for climate change and suburbanization and improving consistency in seed production/seed reproducibility (inbreeding depression with inbreed lines).

Alliumnet update: Provided by Bhabesh Dutta (University of Georgia)

Current website: www.alliumnet.com

The current audience for Alliumnet include: Research and Extension specialists working on pests and diseases affecting Onion and other Allium, Individuals and groups interested in a specific project. This primarily includes funding agencies and policy makers but may include growers/producers. National Allium Research Conference Participants.

Data analytics: At present, Alliumnet has 667 subscribers with 70% of them are from the US. The total page views from 9 Feb to 10 Nov 10 2018 is 520 with >30% of the views for future and current meeting information. Bhabesh Dutta is willing to give web-access to all onion specialists across the country to upload following information regarding onion: peer-review journal articles, extension publications (bulletins, newsletters), Plant disease management reports, pest and disease alerts, and current projects on onion.

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

Nomination for Secretary – The importance of balancing leadership with both academic and industry partners was discussed. Both Peter Rogers and David Burrel were nominated and both agreed to serve in this role. Peter confirmed his willingness to serve as the next secretary in 2019-20 so the membership voted, and he was approved as the 2019 Secretary. David Burrel agreed to start serving his term in 2020.

2019 officers:

Chair: Beth Gugino, Pennsylvania State University (responsible for chairing the 2019 W3008 Annual Meeting)

Vice-Chair: Bhabesh Dutta, University of Georgia (responsible for writing/submitting the 2019 annual project report)

Secretary: Peter Rodgers, Nunhems/Bayer Vegetable Seed (responsible for writing/submitting the 2019 annual meeting minutes)

Past-Chair: Christy Hoepting, Cornell University

Secretary-Elect: David Burrel, National Onion Labs

2019 W3008 Meeting – Steve Loring stated that we are mandated to meet once a year, but the timing of that meeting was up to the project team.

Meeting Options:

Hold jointly with the NOA/NARC/IARS meeting in Madison, WI from 18 to 20 July 2019.

Hold jointly with NOA meeting in Naples, FL in Dec 2019

After discussion, it was decided that it was most time and cost effective to meeting with the NOA/NARC/IARS meeting in July 2019. Beth Gugino will coordinate with Mike Havey to identify a 1 to 2-hour block of time to hold the business portion of the W3008 meeting. Research updates will be captured via presentations at the larger joint meeting.

Christy Hoepting adjourned the meeting at 2:30 pm.

Accomplishments

Objective 1. Evaluate onion germplasm for resistance to pathogens and insects.   Colorado (Uchanski, Bartolo, Gourd): An onion variety trial was conducted at Sakata Farms located north of Brighton, CO (Howard location). Research evaluations this year included emergence, thrips severity, and pink root severity. Thrips populations were counted on Jul 13 and ave. 4.2 thrips per plant.  The pink root severity evaluation was conducted on Aug 20 and ave. 30% infection. Some onion varieties appeared to show some disease tolerance. The trial was hit by a significant hail and rain event on 14 Aug 2018 with 0.81 in of precipitation falling in a very short time. Most leaves were stripped from the plants and the exposed bulbs were bruised by hail stones. As a result, no yields were taken.   Georgia (Dutta): Greenhouse trials were conducted to protect susceptible onion growth stages with Kocide 3000 (copper bactericide) or a plant defense inducer (Actigard) or both. Protective treatments with Kocide 3000 or Kocide 3000+Actigard at bulb initiation and bulb swelling growth stages significantly reduced bulb incidence of center rot. In contrast, applications of Kocide 3000 or Actigard, or Kocide 3000 + Actigard did not significantly reduce bulb incidence after onion seedlings were exposed to thrips indicating that thrips infestation can reduce the efficacy of protective chemical treatments against P. ananatis. Multi-year field trials were conducted to evaluate if onion growth stage directed chemical protection could reduce center rot bulb incidence. Onion plants were protected with (Kocide 3000 or Actigard, or Kocide 3000 + Actigard) at all three growth stages (first leaf senescence, bulb initiation and bulb swelling). The field plots were protected with insecticides for thrips control. The results indicate that Kocide 3000 or Kocide 3000+ Actigard when applied at either bulb initiation or bulb swelling stage can significantly reduce disease incidence in bulbs compared to Actigard only and the untreated control. Marketable yield was also significantly higher when Kocide 3000 and Kocide 3000+Actigard treatments, applied at the bulb initiation and bulb swelling stages.   Researchers at the UGA determined the whole genome sequences of a panel of ten GA Pantoea strains which included both pathogenic as well as non-pathogenic strains. Filtering the genetic content of these strains based on their capacity to cause lesions on onion leaves and create a zone of clearing on red onion bulb scales revealed a small collection of genes that were strongly correlated with onion pathogenicity. There is genetic support that pathogenic isolates produce a plant toxic compound, likely a phosphonate compound, which is responsible for killing onion cells.   Onion cells produce a complex mixture of reactive sulfur compounds against biotic and abiotic stress. These sulfur compounds have been shown to have antibacterial and antifungal properties under laboratory culture conditions. From the comparative genomic analysis, onion pathogenic Pantoea strains predominantly carry a block of nine accessory genes that confers tolerance to onion antimicrobials. This allows the pathogens to survive and thrive in matured onion tissue. Strains that either naturally lack these tolerance genes or have been engineered to inactivate these genes display serious defects in their capacity to colonize onion bulb scales and grow at least 100-fold less than strains possessing these nine tolerance genes. Most of the tolerance genes are predicted to encode enzymes involved in sulfur metabolism.   Idaho (Schroeder, Woodhall, Thornton): A total of 20 cultivars grown in the 2018 Onion Variety Trial at the OSU Malheur Experiment Station were harvested and inoculated with a spore suspension of Fusarium proliferatum (Fp) to evaluate for resistance to Fp storage rot. Bulbs were cured and stored under commercial storage conditions then evaluated and scored for bulb rot four months later. Results indicate that onion bulb cultivars exhibit a range of resistance responses to Fp.  Cultivars Oloroso, Vaquero, Tucannon, Sedona, Pandero and SV6646 were most susceptible. While cultivars 16000, Avalon, and Grand Perfection were the least susceptible. This trial will needs to be repeated to demonstrate the reliability of these cultivars to resist Fp. Knowing how different onion cultivars respond to Fp will provide critical knowledge to stakeholders about cultivar choice to help manage Fp storage rot.   New Mexico (Cramer): Seeds of original, intermediate, and advanced Fusarium basal rot (FBR)-selected populations and one resistant and two susceptible checks were evaluated for resistance to FBR. The inoculation method of 3 x 104 spores per ml placed on a cut basal plate was very effective at causing disease in most bulbs which is important for selecting for resistance. The susceptible check exhibited a high level of disease severity and incidence while the resistant check exhibited less. Of the FBR-selected populations, recent selections of ‘NuMex Crimson’, ‘NuMex Mesa’, and Serrana’ exhibited less disease consistently over years than previous generations. The most recent FBR-resistant selection of ‘NuMex Mesa’, ‘NuMex Sweetpak’, and ‘NuMex Vado’ exhibited less disease than previous generations and the susceptible checks. In some instances, the most recent selection exhibited less disease than the FBR-resistant check. In addition, seed was produced from a total of 40 different FBR-resistant germplasm lines selected in 2017 in association with this project and will be used for further evaluations to ascertain additional progress made for resistance to FBR.   New York (Nault, Hoepting, Pethybridge, Hay): A 2018 study was conducted to evaluate multiple tactics to manage onion thrips in organically produced onion. Two mulch types (reflective and white), two semi-glossy “thrips-resistant” cultivars (Rossa di Milano and B5336 x B5351) and one waxy “thrips-susceptible” cultivar (Bradley), and two insecticide treatments (Entrust and untreated control) were evaluated. Season total numbers of thrips larvae were higher on onions grown on reflective mulch than white mulch, more in the Bradley cultivar than the thrips-resistant cultivars, and more in untreated control plots than Entrust-treated plots. Adult thrips were highest in untreated control plots only. Marketable bulb yields were highest on onions grown on reflective mulch compared with white mulch, higher in Bradley and B5336 x B5351 cultivars than Rossa di Milano, and higher in Entrust than the untreated control. Overall, the most effective tactics for reducing onion thrips infestations while maintaining acceptable marketable yields were to use either Bradley or B5336 x B5351 cultivars, reflective mulch and Entrust. These treatments, along with an effective fungicide program, will be evaluated in 2019 in an on-farm field trial.   Texas (Malla): One hundred thirty-seven onion lines, including cultivars as checks, were evaluated at Uvalde, TX during the 2017-2018 season. Data on diseases, yield and other agronomic traits were recorded. Pink root rot (Phoma terrestris) was an important disease observed during the season. The disease was recorded based on the percentage of root infection where 0% = immune and 100% = highly susceptible. Germplasm showed variation for pink root rot (15 to 60%). Yellow H6 showed the least pink root rot (15%), followed by Texas A&M (TAM) Experimental (Expt)# 50084 (17.5%) and TAM Expt# 50014 (17.5%).   Twenty-four TAM elite onion germplasm were screened for thrips tolerance in Weslaco, TX. Destructive sampling was done to count thrips. For sampling, plants were cut and immediately put into plastic bag. The plant samples were brought in the lab and nymphs and adults were counted. TAM short day sweet onion germplasm showed variation for thrips tolerance when the thrips population was highest, 18 April 2018, just before the harvest. TAM Ext# 50084 had the least (28 thrips per plant), whereas TAM Expt# 43054 had the highest (222 thrips per plant) number of thrips.   Washington (du Toit, Waters, Pappu): Efforts were continued to improve the transmission efficiency of IYSV to onion with a goal to increase the efficiency of screening of onion germplasm for virus resistance under controlled conditions. Successful reproduction of disease symptoms by mechanical inoculation was obtained.   Objective 2. Investigate the biology, ecology and management of onion thrips and other pests.   Colorado (Uchanski, Bartolo, Gourd):  A thrips management study was conducted at Colorado State University’s Arkansas Valley Research Center (AVRC), in a Rocky Ford, CO to determine the efficacy of a tolfenpyrad insecticide in an integrated thrips management program.  Several treatment programs were evaluated and compared to an untreated control and a standard grower management program. Thrips levels, onion yield and market-class distribution were evaluated.  Overall, onion stands, and yields were excellent. Thrips populations were relatively low and non-persistent throughout the season and all treatments programs in the study had similar degrees of efficacy.   New York (Nault, Hoepting, Pethybridge, Hay): A three-year study was conducted to identify the optimal use of Movento (spirotetramat) to manage early-season infestations of onion thrips. Two application treatments (1 vs 2) and two action thresholds (0.1 vs 1 thrips per leaf) were evaluated to determine the highest level and longest period of control. Among the four-application frequency x action threshold combinations evaluated, two applications of Movento with the first timed at 1 thrips per leaf and the second application one week later reduced the thrips infestation to the lowest level for the longest period. Movento will continue to be recommended when thrips populations reach 1 per leaf followed by a second application, 7-10 days later, rather than densities below this level or a single application.   An experiment was conducted to identify an insecticide and rate that most effectively reduces a very high onion thrips infestation. Minecto Pro (abamectin plus cyantranilprole), Exirel (cyantraniliprole) and Radiant SC (spinetoram) were evaluated at their lowest and highest recommended rates. All treatments were applied twice one week apart beginning when the thrips larval density was 3 to 4 per leaf. One week after the second application, only Radiant at 10 fl oz/acre reduced the thrips density to below 2 larvae per leaf; densities of larvae in the Minecto Pro and Exirel treatments were all above 4 larvae per leaf and 2.7 per leaf in the low rate of Radiant.  Radiant SC continues to demonstrate that it is the best product to manage a high thrips infestation.   A two-year study was designed to evaluate the susceptibility of onion thrips populations to Radiant SC in NY. Populations of onion thrips collected from seven commercial onion fields representing four counties were assessed. LC50s generated from feeding assays ranged from 2.07-5.08 ppm, and variation between populations was minimal, both regionally and temporally. The estimated field rate ranges from 141 to 374 ppm, suggesting that onion thrips populations in the areas sampled remain highly susceptible to Radiant, despite its annual use spanning a decade.   Combinations of nitrogen fertilizer and insecticide use were evaluated for onion thrips and thrips-related disease management in a partially thrips-resistant (Avalon) and thrips-susceptible onion cultivar (Bradley) in 2018. All fertilized treatments received 60 lb of urea per acre at planting, and a split application of either 0 lb, 15 lb, 45 lb, or 75 lb of urea per acre applied when onions had between 3-5 leaves. An unfertilized treatment was included as a control. Plots were either sprayed with insecticides following an action threshold or were not treated. The rate of nitrogen did not impact onion thrips densities, incidence of Iris yellow spot (IYS) disease, leaf dieback, the incidence of bacterial rot or marketable yield. Insecticide use reduced thrips densities, the incidence of IYS disease, leaf dieback and bacterial bulb rot. Marketable yield also was highest in the insecticide treatments for both cultivars. Cultivar Avalon had significantly lower onion thrips densities and IYS disease than Bradley, but Avalon had significantly more leaf dieback and bacterial bulb rot than Bradley.   The best combinations of OMRI-listed insecticides and adjuvants were evaluated for managing onion thrips in organically produced onions. Four insecticides (Azera, Entrust, Neemix and PFR 97) and three adjuvants (M-Pede, Nu-Film and Trilogy) were applied weekly. Entrust co-applied with either M-Pede or Trilogy were the most effective insecticide and adjuvant combinations. Neemix and PFR-97 co-applied with NuFilm also provided some control of onion thrips.   Insecticide seed treatment performance was evaluated for managing very high onion maggot infestations in 2017 and 2018. FarMore FI500 (thiamethoxam + spinosad), Regard and FarMore OI100 (both spinosad), Trigard (cyromazine) and Sepresto (clothianidin + imidacloprid) and a fungicide-only control were evaluated. None of the insecticide seed treatments provided a commercially acceptable level of maggot control in either year. Trigard was the only product that ranked among the best treatments for reducing onion maggot damage in both years.  While the current industry standard, FarMore FI500, performed among the best treatments in 2017, it did not in 2018.   Insecticides that would effectively protect leeks from damage caused by the new invasive Allium leafminer (ALM) were evaluated in Fall 2018. Eight conventional and three OMRI-listed products were applied weekly for six weeks from 19 Sept through 25 Oct. Pressure was very high with nearly 100% plants infested and an average of nearly 8 larvae per plant in the untreated control. While all of the conventional products significantly reduced ALM densities in leek compared with levels in the untreated control, all performed statistically similar. The best treatments in descending order were Scorpion (dinotefuran), Exirel, Radiant, Warrior II with zeon technology (lambda-cyhalothrin) and Assail (acetamiprid). The best OMRI-listed product was Entrust (spinoad), while Pyganic Specialty (pyrethrin) and Aza-Direct (azadirachtin) failed to significantly reduce ALM densities compared with those in the untreated control.   Oregon (Reitz, Shock): Thrips and IYSV are the most important pests of onions grown in the Treasure Valley of eastern OR and southwest ID. Ongoing insecticide efficacy trials demonstrated effectiveness of new insecticide use programs to better manage thrips and IYSV. In addition, a regional pest monitoring program provided information to growers on seasonal pest trends, including changing patterns in thrips and IYS incidence in the Treasure Valley.   Texas (Malla): Insect monitoring in Uvalde and Weslaco, TX showed that thrips were prevalent at both locations. Texas A&M Entomologists differentiated thrips species bases on taxonomy. Frankliniella occidentalis was the most predominant thrips species in Uvalde and Weslaco. Thrips tabaci and Frankliniella fusca were also observed in Uvalde but not in Weslaco.   Yellow sticky traps were used to monitor the thrips population on a weekly basis during onion crop season. Onion seedlings were transplanted on the second week of Nov 2017 and harvested on the second week of May 2018. The insect population started to decline after the fourth week of Nov (142 thrips/trap) and reached the lowest (1 thrips/trap) on the second week of Jan. Three population bumps were observed; the first during the third week of Feb (288 thrips/trap), a second during the fourth week of March (1091 thrips/trap) and a final during the second week of April (1600 thrips/ trap). Based on thrips monitoring data, growers need to inspect fields toward the end of the winter and start insect management practices.   Washington (du Toit, Waters, Pappu): Several conventional and organic pesticides were evaluated for their ability to manage onion thrips populations. The organic product Entrust was found to be the most efficacious of the organic materials tested. For the conventional products, Radiant, Agrimek, Exirel, Minecto Pro, and Lannate were the most efficacious products. Movento and Torac provided a moderate level of control.   Thrips from commercial onion fields were evaluated for their level of resistance to the commonly used insecticide Lannate (methomyl). Varying levels of resistance were detected, presumably based on the frequency of use of the product. The organic field, that has not had the product applied contained thrips that were completely susceptible to the field dose of the product. The four conventional fields that were evaluated ranged from 58 to 80% mortality at the field dose. These levels of control at the field dose suggest the onset of field resistance to Lannate. This information will be used to help producers modify their insect management strategies to mitigate further resistance development and achieve adequate control of onion thrips.   Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens.   California (Putnam): In Oct 2017, a field trial was initiated in Holtville, CA to evaluate the utility of weather-based models to schedule fungicide applications to manage downy mildew of onions for processing. A weather station was established within the trial to measure standard parameters at a height of 2 m, plus temperature, relative humidity, and leaf wetness within the plant canopy. Four disease models were (DOWNCAST, DOWNCAST modified by de Visser, DOWNCAST used by the University of Guelph, and ONIMIL) into a single computer script to allow output from the models to be produced simultaneously. In response to the models, fungicide applications for model-based treatments were made from 0 to 2 times over the course of the growing season, whereas 4 applications were made for the standard calendar-based treatment. Downy mildew was not observed in the study area, consistent with overall very low downy mildew pressure in the California desert in the winter of 2017-2018. Under low disease pressure, 4 applications were made for the standard calendar-based treatment, whereas weather-based models triggered from 0 to 2 applications.   Colorado (Uchanski, Bartolo, Gourd): Uchanski evaluated the effect of potassium fertility on Iris yellow spot virus (IYSV) severity in onion in 2016 and 2017.  Four potassium treatments were applied to field grown onions in Fort Collins, CO: treatment 1: 250g muriate of potash per 10 ft of row; treatment 2: 750g muriate of potash per 10 ft of row; treatment 3: 250g potassium sulfate per 10 ft of row; treatment 4: 750g potassium sulfate per 10 ft of row; control: no additional potassium added.   In both years, IYSV incidence (percentage as determined by ELISA) increased numerically in treatments 1 and 2.  However, after further analysis those differences were not found to be statistically significant. In addition, IYSV incidence was low (i.e. < 15%) in both years, so the numerical difference was likely not biologically relevant.  From these two studies we conclude that elevated soil potassium levels do not appear to significantly increase the incidence of IYSV in northern CO.   Idaho (Schroeder, Woodhall, Thornton): A validated real-time PCR detection method for Fusarium proliferatum (Fp) was developed to determine the presence and amount of pathogen present. From three experiments the reaction efficiency of the assay was between 90 and 104% which is within the ideal range for a real-time PCR assay. The assay was tested on 6 different Fp isolates and consistent detection was observed. In addition, 20 other fungal species were tested including related Fusarium species and no cross reaction was observed. The assay was successfully used to detect the pathogen in onion bulbs including asymptomatic bulbs. Over half the bulbs tested were positive for the fungus although there was no relationship between symptoms and presence of the pathogen.   The presence of airborne inoculum of Fp was tested using a Burkard multi-vial sampler and qPCR. Spore samplers were situated at Parma and in Kimberly to compare between onion producing and non-producing areas. No Fp was detected in the air samplers between May and September. Soil is therefore the most likely source of inoculum since seed is already treated for potential fungal pathogens. DNA was extracted from soil and Fp was detected in 39% of soils in 2017 and 33% in 2018. Therefore, soil is likely to be the main source of inoculum.   To determine the infection window of Fp on onions during the growing season, bulbs were removed from a field at Parma at four different dates and inoculated with Fp spores and incubated at 90% RH and 39°C for two weeks. Bulbs were then cut open and scored for presence of internal defects. Disease levels were slightly higher in mid-July and early Aug although disease was observed at all times. This is consistent with rain events that occurred in 2015 and 2016 during a similar period. The initial theory that high temperatures in July and Aug were the cause of the disease is unlikely since similar temperatures have been high in all years between 2015-2018. To confirm this, monitoring of the disease and weather will continue as several years data will be required to support this hypothesis.   To determine the impact temperature and curing parameters on progress of Fp in onion bulbs during storage, onion bulbs were inoculated with 5 x 105 spores/ml, cured at 77, 86, 95 or 104°F for two days and stored at 41°F. Bulbs were destructively harvested at 4 or 6 mo. of storage and evaluated for percent of bulb rot. A general trend was observed that less bulb rot occurred when bulbs were cured at the higher temperatures, regardless of storage length. In addition, less bulb rot was occurred when bulbs were stored for 4 months rather than 6 months irrespective of the curing temperatures. The notable exception was onion bulbs cured at 104°F for two weeks exhibited significant bulb rot most likely resulting from not only the pathogen but tissue damage caused by long-term exposure to high temperatures. These assays were repeated to confirm that these data. This information will be used by the stakeholders as a cultural management tool for the control of Fp in storage.   New York (Nault, Hoepting, Pethybridge, Hay): A 2018 study was conducted to evaluate OMRI-listed fungicides for managing Stemphylium vesicarium on three onion cultivars (Bradley, Ailsa Craig, and Avalon). Plots were assessed visually three times during the season for percent leaf length blighted and bulbs were graded by number and weight into boiler, standard, jumbo, colossal or cull size classes. Badge X2, Kocide 3000-O and the non-OMRI-listed product Oso were all effective at reducing the incidence of SLB. Cultivars Bradley and Ailsa Craig had significantly less disease incidence than Avalon. Avalon had significantly higher marketable yield than Bradley, which in turn had significantly higher yield than Ailsa Craig. Thrips populations in the field may have resulted in lower yields of Bradley (thrips-susceptible) compared with Avalon (thrips-resistant). The OMRI-listed fungicides, Badge X2 and Kocide 3000-O, will be evaluated in 2019 in an on-farm field trial.   Oregon (Reitz, Shock): Recent increases in internal onion bulb decomposition of onion bulbs with underdeveloped scales in the neck region are thought to have resulted from unusually warm growing seasons.  A field trial was conducted to determine whether heat is a factor in bulb decomposition and whether or not treatments that increase or reduce the heat load in the soil and onion bulbs would affect the expression of internal bulb decomposition. Results show that total yield, marketable yield, and yield of bulbs larger than 4 in decreased with increasing bulb and soil temperature although differences among treatments in bulb rots was not evident.   Oregon/California (Dung (OR), Wilson (CA), Turini (CA)): White rot is a major fungal disease of onion and garlic in the western U.S. Field studies were conducted in Tulelake, CA and western Fresno County, CA that were planted to onion and garlic, respectively, to investigate an IPM solution for white rot that integrates sclerotia germination biostimulants and in-furrow fungicides. Main plot treatments consisted of sclerotia germination biostimulants (garlic juice or garlic oil) that were shank-injected in the spring and/or fall prior to planting. The Tulelake site also included allyl isothiocyanate (AITC) and metam sodium treatments. Sclerotia germination biostimulants were compared to non-treated plots and plots treated with diallyl disulfide (DADS) at both sites. Tebuconazole was applied in-furrow as a split-plot treatment at both sites at planting.    At the Tulelake site, the greatest reductions in sclerotia populations were observed in plots treated with garlic oil in the spring and fall (76%), DADS (70%), and garlic oil (spring) + AITC (fall) (66%). In-furrow applications of tebuconazole significantly increased onion stand and reduced late season onion leaf dieback and AUDPC values compared to the no-fungicide control (P ≤ 0.0002). Although not significantly greater than the untreated control, garlic oil (spring) + AITC (fall), garlic juice (spring), and garlic oil (spring and fall) exhibited the highest yields of disease-free onion bulbs. In-furrow applications of tebuconazole increased disease-free onion yield compared to the no-fungicide control (P < 0.0001). At the Fresno site, significant effect of germination stimulant on pre-plant sclerotia counts was not observed (P = 0.62), which may have been due to variability among plots in the commercial field. In-furrow applications of tebuconazole increased total garlic yield (P < 0.0001) and decreased the number of garlic bulbs with severe disease symptoms (P = 0.049). Sclerotia populations increased greatly from onion and garlic planting to harvest at both sites in plots not treated with an in-furrow application of tebuconazole at (P < 0.04), suggesting that tebuconazole may help prevent the buildup of sclerotia in fields after an Allium crop.   Pennsylvania (Gugino): A replicated multi-factorial center rot (P. agglomerans and P. ananatis) research trial was established to evaluate several bacterial inoculation methods (three methods) and inoculation timing (three plant growth stages). The goal was to identify a consistent inoculation method and time to inoculate the plants to achieve uniform disease distribution throughout the plots. This in turn would reduce variability in disease pressure across the trial and facilitate the more standardized evaluation of management tactics which could then be employed in multiple onion growing regions across the U.S. Unfortunately, the trial was terminated prematurely due to the extreme wet weather in the central and eastern parts of PA this past season.   Texas (Malla): Botrytis and Stemphylium leaf blight were observed in a seed production nursery where bulbs were transplanted in Uvalde, TX. Bravo (2 pt/A) was sprayed once early in the season when plants were at 3 to 4 leaf stage. Fungicide was not effective in controlling disease. Majority of seed scapes died late in the crop season. A study is needed to develop a better fungicide program to manage foliar diseases in onion.    Due to high thrips population in Uvalde, TX, leaf samples were sent to test for the tospovirus, Iris yellow spot virus, at Nischwitz Lab (Utah State University). All of the leaf samples were tested negative for IYSV. TAM researchers were also not able to detect tospovirus in tomato, pepper and melon in Uvalde and Weslaco, TX.   Washington (du Toit, Waters, Pappu): Finished a 3-year WSDA SCBG project on evaluating arbuscular mycorrhizal fungi (AMF) inoculants for enhancing onion production and management of soilborne pathogens in the Columbia Basin. Published results showing that that moderate to high soil P levels typically used by onion growers in this region significantly reduce root colonization by AMF, negating the benefits of AMF inoculants in onion crops.   A field trial was established in Pasco, WA to evaluate products for control of downy mildew in onion bulb production using infected plants that were generated using inoculum obtained from an infected, overwintered onion seed crop. Warm, dry conditions in the Columbia Basin in 2018 limited development of downy mildew to the point there was inadequate disease to differentiate efficacy of the products.   du Toit provided diagnosis and associated management recommendations for 30 onion samples from growers in the Pacific Northwest and western USA. Waters visited 20 commercial onion fields in Washington State to help producers identify pest and diseases issues and help develop control recommendations.   Objective 4. Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management.   California (Putnam): Putnam was approached by one seed company to expand this project into onion seed fields in other regions of California as well as by an agricultural services company about possibilities for collaboration.    Colorado (Uchanski, Bartolo, Gourd):  In Southern Colorado at Colorado State University’s AVRC, a Field Day event was conducted with a total of 150 participants. The tour included a mixture of growers, seed company representatives, and federal and state agency personnel. Research results will also be made available at the Colorado Fruits and Vegetable Growers Association (CFVGA) on February 25 and 26, 2019.  The 2017 results were shared at the 2018 CFVGA conference, also in Denver.   New York (Nault, Hoepting, Pethybridge, Hay): 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. Details of these interactions are included in the Presentations section.   Oregon (Reitz, Shock): An onion pest monitoring program and new insecticide recommendations allowed growers to reduce insecticide applications.   Pennsylvania (Gugino): In the first year of this project, emphasis was placed on disseminating results from the previous W2008 regional project at a number of local winter grower meetings and summer pest and disease walks. A total of five presentations reaching over 490 participants were given that included at least impart the identification and management of bacterial diseases of onion.   Washington (du Toit, Waters, Pappu): W-3008 annual meeting was held in Kennewick, WA on 13 Nov. 2018 with approximately 60 participants from across the US. Attendees shared updates on onion production in various states, and progress reports on onion research and extension projects. The meeting was followed by a field tour and packing facility/storage facility tour outside Pasco. Tim Waters and Lindsey du Toit were the local arrangements committee. Lindsey du Toit served as past chair of the W-3008 multi-state project in 2018. du Toit prepared a summary of the W-3008 annual meeting for publication in the January/February 2019 issue of Onion World based on the minutes of the meeting.   Washington State University Extension Onion Alerts, issued through the 2018 growing season, contributed timely information on diagnosis and management of onion insect pests and diseases in the Columbia Basin and Walla Walla regions of production. Onion Alerts were released online on 24 Apr, 23 May, 31 May, 3 Jul, 16 Aug, 27 Aug, 1 Oct, and 31 Oct 2018 to over 600 subscribers (<a href="https://us13.campaign-archive.com/?u=2eff8714011ff4bfba18a0704&id=d75dc96e7f">https://us13.campaign-archive.com/?u=2eff8714011ff4bfba18a0704&id=d75dc96e7f</a>).

Publications

du Toit, L.J., Derie, M.L., Holmes, B.J., Henrichs, B.A., Winkler, L.R., Waters, T.D., and Darner, J. 2018. The effects of arbuscular mycorrhizal fungal inoculants on pink root and yield in an onion crop near Paterson, WA, 2016. Plant Disease Management Reports 12:V102.   du Toit, L., and Yorgey, G. 2018. Onion stunting after cereal cover crops. Page 6. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Page 7. Efficacy of fungicide applications to manage onion stunting caused by Rhizoctonia spp. Pages 7-8. In: Strip-tillage for onions and sweet corn, Lorin Grigg. Farmer to Farmer Case Study Series on Increasing Resilience among Farmers in the Pacific Northwest. Washington State University Extension PNW702.   du Toit, L.J., Waters, T., Derie, M., Holmes, B., Darner, J., Henrichs, B., Knerr, J., Miller, C.E., Morgan, P., and Brouwer, L. 2018. Do AMF inoculants help onion crops? Pp. 11-12 in: 2018 Washington State University Onion Field Day Handouts. 13 pp.   Hoepting, C.A.  2018.  Effect of fungicide timing on Stemphylium leaf blight on onion, 2017.  Plant Disease Management Reports 12: V101.   Hoepting, C.A.  2018.  Efficacy of selected products for control of bacterial bulb decay in onion, 2017.  Plant Disease Management Reports 12: V143.   Hoepting, C.A.  2018. Effect of fungicide programs for control of Stemphylium leaf blight on onion, 2017.  Plant Disease Management Reports 12: V144.   Hoepting, C.A.  2018.  Efficacy of Fontelis for control of pink root in onion, 2017. Plant Disease Management Reports 12: V145.   Hoepting, C.A.  2018.  Efficacy of fungicide treatments for control of Stemphylium leaf blight on onion, 2017. Plant Disease Management Reports 12: V146.   Hoepting, C.A.  2018.  Efficacy of seed and in-furrow treatments for control of onion smut and damping off in onion, 2017.  Plant Disease Management Reports 12: ST007.   Kamal, N. and C.S. Cramer. 2018. Selection progress for resistance to Iris yellow spot in onions. HortScience 53:1088-1094.   Knerr, A.J., Wheeler, D., Schlatter, D., Sharma-Poudyal, D., du Toit, L.J., and Paulitz, T.C. 2018. Arbuscular mycorrhizal fungal communities in organic and conventional onion crops in the Columbia Basin of the Pacific Northwest USA. Phytobiomes 2: in press. <a href="http://dx.doi.org/10/.1094/PBIOMES-05-18-0022-R">http://dx.doi.org/10/.1094/PBIOMES-05-18-0022-R</a>   Leach, A. B., C. A. Hoepting and B. A. Nault. 2018. Grower adoption of insecticide resistance management practices increase with extension-based program. Pest Management Science: DOI 10.1002/ps.5150.   Leach, A., M. Fuchs, R. Harding, R. Schmidt-Jeffris and B. A. Nault. 2018. Importance of transplanted onions contributing to late-season Iris yellow spot virus epidemics in New York. Plant Dis. 102: 1264-1272.   Leach, A., B. A. Nault, and C. Hoepting. 2018. Insecticide sequences to manage onion thrips in onion in 2018. Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 14(10):  8-9.   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>.   Pfeufer, E.E. and B.K. Gugino. Environmental management factors associated with bacterial diseases of onion in Pennsylvania. Plant Disease. doi.org/10.1094/PDIS-11-17-1703-RE.   Waters, T.D., Darner, J., Adesanya, A., Walsh, D. and Kinion, D. Entomology Research Report for Onions. In: 2018 Washington State University Onion Field Day Handouts. 13 pp.   Winkler, L., du Toit, L., and Waters, T. 2018. Do onion growers benefit from mycorrhizal inoculants ? The effects of mycorrhizal inoculants on onion crops in the Columbia Basin. Onion World Nov. 2018: in press.   Other Activities   <ol> <li> Abstracts and Papers at International Professional Meetings</li> </ol>   du Toit, L.J., and Correll, J.C. 2018. Case studies of the complexity of seedborne and seed transmitted fungi affecting regional and global seed trade. Guest speaker, joint symposium of American Phytopathological Society (APS) and Società Italiana di Patologia Vegetale (SIPaV), 24th National Congress of SIPaV, 5-7 Sep. 2018, Ancona, Italy.   Leach, A., F. Hay, R. Harding, and B. Nault. 2018. Relationship between Stemphylium vesicarium and onion thrips (Thrips tabaci) in the development of Stemphylium leaf blight disease. Poster Presentation. International Congress of Plant Pathology. Boston, MA. July 29-August 3, 2018.   Leach, A., C. Hoepting and B. Nault. 2018. Successful adoption of action threshold-based insecticide programs for thrips management in onion. 9th International IPM Symposium. Baltimore, MD. March 21, 2018.   Tabassum, A., S.V. Ramesh, Y. Zhai, and H.R. Pappu. 2018. Molecular evolutionary genomics and population structure of Iris yellow spot virus (Family: Tospoviridae; Genus: Orthotospovirus). 11th International Congress of Plant Pathology, Boston, MA.  July 29-August 3, 2018.   <ol start="2"> <li> Abstracts and Papers at National Professional Meetings </li> </ol>   Fleischer, S., T. Elkner, C. McGrady, D. Roberts, B. A. Nault, T. Rusinek, E. Grundberg, J. Ali, S. Ray and B. Lingbeek. 2018. Allium leafminer: A new invasive threat to Allium crops in North America. ESA, ESC, and ESBC Joint Annual Meeting, Vancouver, CA. November 13, 2018   Leach, A., S. Reiners, M. Fuchs, C. Hoepting and B. A. Nault. 2018. IPM and the human element: developing programs to control onion thrips in onion. Purdue University entomology department seminar series, West Lafayette, IN. December 6, 2018.   Leach, A., C. Hoepting and B. A. Nault. 2018. Increasing use of action thresholds in managing onion thrips on New York onion farms. ESA, ESC, and ESBC Joint Annual Meeting, Vancouver, CA. November 11-14, 2018.   Leach, A., S. Reiners and B. Nault. 2018. Evaluating effects of nitrogen fertilizer and insecticide use in managing onion thrips (Thrips tabaci) in onion. Entomological Society of America’s Eastern Branch meeting. Annapolis, MD. March 18, 2018.   Malla, S., M. Khanal, D. Silwal, J. Jifon, B. Patil, K. Crosby, and E. Correa. Short Day Onion Germplasm Evaluation in Southern Texas. American Society for Horticultural Science, Washington, D.C. 31 July – 3 Aug. 2018.   Mandal, S. and C.S. Cramer. 2018. Breeding for Fusarium basal rot resistance in short-day onions, p. 106. In: Proc. 2018 American Society for Horticultural Science Annual Conf., C. Sams (Ed.) Washington, DC. (Abstr.)   Nault, B. A., A. Leach, C. Hoepting, E. Moretti, and J. Scott. 2018. Adoption and Success of an IRM Program for onion thrips in onion:  So good so far! ESA, ESC, and ESBC Joint Annual Meeting, Vancouver, CA. November 12, 2018   Nault, B. A., S. Fleischer, E. Grundberg, T. Rusinek, D. Roberts and T. Elkner. 2018. Biology and management of Phytomyza gymnostoma: a new invasive pest of Allium crops in the eastern US. Entomological Society of America’s Eastern Branch meeting. Annapolis, MD. March 19, 2018.   Nault, B.A., S.R. Reitz, T.D. Waters. 2017 Current and Future Management of Onion Thrips-Transmitted Iris yellow spot virus (IYSV) in Onion. Symposium on P-IE Section Symposium: Inspiring a New Cadre of Vegetable Specialists By Sharing Expertise Related to Piercing-Sucking Insects of Economic Importance in Vegetable Production. Entomological Society of America, Denver, CO, November 2017. Silwal, D., S. Malla, and M. Khanal. 2018. Short Day Onion (Allium cepa) Germplasm Evaluation for Agronomic and Disease Tolerance in South Texas. Southern Region American Society for Horticultural Science Meeting, Jacksonville, FL. 2-4 Feb. 2018.   <ol start="3"> <li> Reports at Grower Meetings and Field Days</li> </ol>   Bartolo, M. Colorado Produce Day, January 2018.   Bartolo, M. AVRC Field Day, September 2018.   Bartolo, M. Specialty Crops Program Field Day, August 29, 2018.   Cramer, C.S. 2017. Control of onion thrips and IYS through interplant N. cataria during onion seed production. Multistate Research Project W3008: Integrated Onion Pest and Disease Management, Annual Meeting, and 2017 Great Lakes Fruit and Vegetable Expo, Grand Rapids, MI, Dec. 4, 2017.   Cramer, C.S. 2017. Progress for breeding for Fusarium basal rot resistance in onions. Multistate Research Project W3008: Integrated Onion Pest and Disease Management, Annual Meeting, and 2017 Great Lakes Fruit and Vegetable Expo, Grand Rapids, MI, Dec. 4, 2017.   du Toit, L.J. Management of Fusarium basal rot of onion. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (200 people).   du Toit, L.J. Regionally appropriate fungicide programs for common onion pathogens in the Columbia Basin. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (200 people).   du Toit, L.J. Impact of fungicides on plant health. Invited presentation, Pest Management Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (175 people).   du Toit, L.J. Complexities and synergies in large-scale conventional and organic agriculture in Washington. Invited presentation, Organic Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (150 people).   du Toit, L.J. Case studies of the complexity of seedborne and seed transmitted fungi affecting regional and global seed trade. Guest speaker at the joint symposium of the American Phytopathological Society (APS) and the Società Italiana di Patologia Vegetale (SIPaV), 24th National Congress of SIPaV, 5-7 Sep. 2018, Ancona, Italy. (see Abstracts above) (~250 people).   du Toit, L.J. Conventional and organic disease control strategies for specialty crops. Invited presentation at 2018 Colorado Fruit & Vegetable Growers’ Association Annual Meeting, 19-20 Feb. 2018, Denver, CO (50 people).   du Toit, L.J. Allium, bean, and crucifer seed quarantines in Washington: Current status and future needs. Annual Basin Producers’ 2018 Pesticide Recertification Day, 19 Jan. 2018, Moses Lake, WA (175 people).   du Toit, L.J. A review of onion diseases – identification and management. 4-hour invited presentation at the 2018 Walla Walla Onion Growers’ Meeting organized by CHS Primeland, 18 Jan. 2018, Walla Walla, WA (12 people).   du Toit, L.J. Allium, bean, and crucifer seed quarantines in Washington: Current status and future needs. Columbia Basin Crop Consultants’ Assoc. Short Course, 17 Jan. 2018, Moses Lake, WA (150 people).   du Toit, L.J. Seedborne and seed transmitted plant pathogens. Columbia Basin Crop Consultants’ Assoc. Short Course, 17 Jan. 2018, Moses Lake, WA (100 people). Gugino, B.K. Managing bacterial diseases in vegetables, Instructor, Extension Program, New Holland Vegetable Day, Yoder's Restaurant and Buffet, 15 Jan 2018, New Holland, PA (50 participants).   Gugino, B.K. Vegetable disease management, Instructor, Extension Program, Ephrata Agway Vegetable Grower Meeting, Shady Maple Banquet Center, 20 Dec, 2017, East Earl, PA (250 participants).   Gugino, B.K. Disease management 101: Problems from 2017 and management recommendations, Quarryville Produce Growers Meeting. Hoffman Building at Solanco Fairgrounds, 14, Dec 2017, Quarryville, PA, (100 participants).   Gugino, B.K. Vegetable disease update and field walk, Instructor, Extension Program, Central Susquehanna Vegetable Twilight Meeting, Amos Martin Farm, 17 Jul 2018, Middleburg, PA., (72 participants).   Gugino, B.K. Pest and disease walk, Instructor, Extension Program, Sugar Valley Vegetable Grower Twilight Meeting, Amos Glick Farm, 16 July 2018, Loganton, PA, (15 participants).   Hoepting, C.A.  2018. Putting it all together; Improved SLB fungicide program – Effective, affordable and with Best Resistance Management Practices.  Empire State Producers Expo – Onion SLB Fungicide Resistance Workshop. Syracuse, NY, USA: January 16, 2018 (61 participants).    Hoepting, C.A.  2018. Managing Stemphylium leaf blight of onion with fungicides in New York.  Empire State Producers Expo – Onion SLB Fungicide Resistance Workshop. Syracuse, NY, USA: January 16, 2018 (61 participants).    Hoepting, C.A. 2018.  Managing Stemphylium leaf blight of onion with fungicides in New York.  Orange County Onion School.  Middleton, NY, USA: February 28, 2018 (50 participants).   Hoepting, C.A.  2018.  Fungicide trial demonstration in direct-seeded onion for control of Botrytis leaf blight and Stemphylium leaf blight.  Annual Oswego County Onion Growers Twilight Meeting.  Oswego, NY, USA: August 22, 2018 (45 participants).   Hoepting, C.A.  2018.  New seed treatment for control of onion smut.  Annual Oswego County Onion Growers Twilight Meeting.  Oswego, NY, USA: August 22, 2018 (45 participants).   Hoepting, C.A.  2018.  Noueautés sur le contrôle des ennemis de l-oignon/New arrivals on the control of the enemies of the onion.  Les Journées Horticoles & Grandes Cultures.  St. Rémi, Quebec, Canada: December 4, 2018 (105 particpants).   Jepson, P. and S. Reitz. 2018. Pesticide Resistance Management. Idaho-Malheur County Onion Growers Associations Annual Meeting.   Leach, A., R. Harding, M. Fuchs and B. A. Nault. 2018. Impacts of nitrogen fertilizer in muck onion production. Poster presentation. Great Lakes Fruit and Vegetable Expo, Grand Rapids, MI. December 4-6, 2018.   Leach, A., E. Moretti and B. A. Nault. 2018. First look at 2018 results for onion thrips and onion maggot management. Oswego onion grower twilight meeting, Oswego, NY. August 22, 2018.   Leach, A., S. Reiners, F. Hay, M. Fuchs, R. Harding, and B. A. Nault. 2018. Evaluating interactions between onion thrips and associated plant pathogens for improved management in onion. Sixty-seventh Annual Muck Vegetable Growers Conference.  Bradford, Ontario Canada.  March 28-29, 2018.   Leach, A., S. Reiners, M. Fuchs and B. A. Nault. 2018. Unravelling the interactions among variety, fertility, yield, onion thrips and diseases, and implications for improved management practices. Empire State Producers EXPO, January 17, 2018. Syracuse, NY. <a href="http://www.hort.cornell.edu/expo/proceedings/2018/Onions%20Unravelling%20Interactions%20Ashely%20Leach.pdf">http://www.hort.cornell.edu/expo/proceedings/2018/Onions%20Unravelling%20Interactions%20Ashely%20Leach.pdf</a>   Nault, B. A. 2018. Onion insect pest management update. Orange County Onion School.  Middleton, NY. February 28, 2018.   Putnam, A. Evaluation of weather-based models for management of onion downy mildew. California Garlic and Onion Symposium, UC Cooperative Extension, 12 Feb 2018, Tulare, CA.   Putnam, A. Downy mildew and other diseases of vegetables in desert production. Desert Research Symposium, UC Cooperative Extension and California Association of Pest Control Advisors, 28 Feb 2018, Palm Desert, CA.   Putnam, A. Management of downy mildew of vegetables in the Imperial Valley. Agronomic Crops and Irrigation Water Management Field Day, UC Cooperative Extension, 28 April 2018, Holtville, CA.   Putnam, A. Evaluation of weather-based models for management of onion downy mildew. Agronomic Crops and Irrigation Water Management Field Day, UC Cooperative Extension, 18 April 2018, Holtville, CA.   Reitz, S.R. 2018. Onion production tour. Malheur Summer Farm Festival, July 2018.   Reitz, S. 2018. Thrips/IYSV Management. Idaho-Malheur County Onion Growers Associations Annual Meeting.   Reitz,S. 2018. Thrips and IYSV Management in the Treasure Valley. Pacific Northwest Vegetable Association Annual Meeting.   Schroeder, B.K. Impact of temperature on Fusarium proliferatum and the development of bulb rot in storage. Idaho and Malheur County Onion Growers’ Association 58th Annual Meeting. 6 Feb 2018.   Shock, C. 2018. Incomplete Scale and heat enhance the infection of onion bulbs. Pacific Northwest Vegetable Association Annual Meeting.   Waters, T.D. Thrips Control in Dry Bulb Onions. Pacific Northwest Insect Management Conference, January 8, 2018 Portland, OR. (45 people).   Waters, T. D.  Insect IPM Update. Simplot Grower Solutions Meeting, February 6, 2018. Pasco, WA. (65 people).   Waters, T. D. Potato and Onion Insect IPM Update. Agrinorthwest Agronomy Meeting. February 6, 2018.  Kennewick WA. (45 people).   Waters, T.D. Insect Control in Potato and Onion. Corteva Regional Customer Meeting, February 15, 2018. Las Vegas, NV. (125 people).   Waters, T. D. Thrips and Seedcorn Maggot Control in Onions. 2018 Walla Walla Onion Growers’ Meeting organized by CHS Primeland, 18 Jan. 2018, Walla Walla, WA (12 people)   Waters, T.D. and L. duToit. WSU Extension Onion Field Day, 30 Aug. 2018, Hartley Farms, Benton City, WA. Presented onion mycorrhizae research update to growers, seed industry, extension personnel, researchers, etc. (125 people).   Water, T.D. Washington Pest Control Tour or central WA, Washington State Commission on Pesticide Registration, 24-26 Jul. 2018. Presented on vegetable seed production and research needs, including pathology research, to ~50 federal/state legislators or staff, agricultural industry representatives, WA State Dept. of Agriculture, Ecology, and Labor & Industries; WSU CAHNRS administrators, National Marine Fisheries Service, US Environmental Protection Agency, etc. on 25 Jul. near Othello, WA. (75 people).   Water, T.D. WSU Extension Onion Field Day, 30 Aug. 2018, Hartley Farms, Benton City, WA. Presented onion thrips research update to growers, seed industry, extension personnel, researchers, etc. (125 people).   <ol start="4"> <li>Newsletter Articles</li> </ol>   Hoepting, C.A. 2018.  Fungicide recommendations for Botrytis leaf blight in onion.  Veg Edge, 14(12): 9-10.   Hoepting, C.A. 2018. New developments for managing Stemphylium leaf blight in onion: Managing fungicide resistance is crucial.  Veg Edge, 14(13): 6-8.   Hoepting, C.A.  2018.  New recommendations for using Surchlor (a.i. sodium hypochlorite), as in “pool chlorine”) for bacterial diseases of bulb onion.  Veg Edge, 14(14): 6-7.   Hoepting, C.A.  2018.  Onion thrips management after Movento.  Veg Edge, 14(15): 5-6.   Hoepting, C.A. 2018. Time to protect onions from downy mildew.  Veg Edge, 14(16): 3-4.   Hoepting, C.A.  2018.  Leafminers in onion: Native vs. Invasive species.  Veg Edge, 14(16): 6-7.   Hoepting, C.A.  2018.  The rot race: Trying to avoid bacterial bulb rot in onion at harvest.  Veg Edge, 14(18): 1-3.   Hoepting, C.A.  2018.  Harvest and post-harvest tips for best onion quality.  Veg Edge, 14(18): 6-7.   Hoepting, C.A.  2018. Artificial curing significantly reduces onion bacterial bulb rot.  Veg Edge, 14(22): 4-5.   Hoepting, C.A.  2018. EverGol Prime – New seed treatment for onion smut available now.  Veg Edge, 14(23): 6-7.   Hoepting, C.A.  2018.  Onion growers should make 2019 a Trigard a seed treatment year for onion maggot control.  Veg Edge, 14(23): 8-9.   <ol start="5"> <li>Annual Reports</li> </ol>  Reitz, S. R. 2018. Monitoring Onion Pests Across the Treasure Valley - 2017. pp. 128-131. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2017, Department of Crop and Soil Science Ext/CrS 159. <a href="http://www.cropinfo.net/pdf/ar/2017/2017-013-OPMReport.pdf">http://www.cropinfo.net/pdf/ar/2017/2017-013-OPMReport.pdf</a>                                        Reitz, S. R., Shock, C. C., Feibert, E. B. G., Rivera, A., and Saunders, L. D. 2018. Thrips and Iris Yellow Spot Virus Management in the Treasure Valley. pp. 113-127. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2017, Department of Crop and Soil Science Ext/CrS 159. <a href="http://www.cropinfo.net/pdf/ar/2017/2017-012-InsecticideRotation.pdf">http://www.cropinfo.net/pdf/ar/2017/2017-012-InsecticideRotation.pdf</a>   Shock, C. C., Feibert, E. B. G., Rivera, A., Wieland, K. D., & Saunders, L. D. 2018. Onion internal quality in response to artificial heat and heat mitigation during bulb development. pp. 42-59. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2017, Department of Crop and Soil Science Ext/CrS 159. <a href="http://www.cropinfo.net/AnnualReports/2017/2017-004-OnionIntRotHeat.php">http://www.cropinfo.net/AnnualReports/2017/2017-004-OnionIntRotHeat.php</a>  Shock, C. C., Feibert, E. B. G., Rivera, A., & Saunders, L. D. 2018. Timing the Occurrence of Internal Quality Problems in Onion Bulbs. pp. 60-72. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2017, Department of Crop and Soil Science Ext/CrS 159. <a href="http://www.cropinfo.net/AnnualReports/2017/2017-006-OnionDiatom.php">http://www.cropinfo.net/AnnualReports/2017/2017-006-OnionDiatom.php</a> Shock, C. C. Feibert, E. B. G., Rivera, A., & Saunders, L. D. 2018. Evaluation of Chlorine and Diatomaceous Earth for Control of Internal Decay in Onion Bulbs. pp. 73-79. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2017, Department of Crop and Soil Science Ext/CrS 159. <a href="http://www.cropinfo.net/AnnualReports/2017/2017-006-OnionDiatom.php">http://www.cropinfo.net/AnnualReports/2017/2017-006-OnionDiatom.php</a>   <ol start="6"> <li>Internet Resources</li> </ol>   Alliumnet.com: Provides a list of research and extension specialists working on pests and diseases; focuses on collaboration among research, extension and industry <a href="http://alliumnet.bugwoodcloud.org">http://alliumnet.bugwoodcloud.org</a>   Colorado Research results are available on our web site: <a href="http://adamscountextension.com">http://adamscountextension.com</a> CSU Specialty Crops:  <a href="https://specialtycrops.agsci.colostate.edu/research-and-projects/">https://specialtycrops.agsci.colostate.edu/research-and-projects/</a>   Hoepting, C.A.  2018. Cornell onion fungicide “cheat sheet” for leaf diseases, 2018. Cornell Cooperative Extension - Cornell Vegetable Program. Online: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_689.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_689.pdf</a>.     Nault, B.A. and A. Leach.  2018. Guidelines for 2018 Onion thrips management in Onion. Decision Diagram. Cornell Cooperative Extension - Cornell Vegetable Program. Online: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_685.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_685.pdf</a>.   Oregon State University Malheur Experiment Station: <a href="http://Cropinfo.net">Cropinfo.net</a>   Pacific Northwest Vegetable Extension Group (PNW VEG), a tri-state (OR, WA, ID) consortium of 25 university and USDA ARS vegetable researchers and extension specialists met monthly by conference call during the 2018 field season, from May through October, to discuss vegetable production status in the region, including pest, disease, and other issues affecting production of onion and other vegetables. The team website was updated regularly, including the Photo Gallery and other resources for vegetable stakeholders : <a href="http://mtvernon.wsu.edu/path_team/diseasegallery.htm">http://mtvernon.wsu.edu/path_team/diseasegallery.htm</a>   Wohleb, C.H., Waters, T.W., and du Toit, L.J. 2018. Washington State University Extension Onion Alerts. Contributed disease information and photos for WSU Onion Alerts released online on 24 Apr., 23 May, 31 May, 3 Jul., 16 Aug., 27 Aug., 1 Oct., and 31 Oct. 2018. <a href="https://us13.campaign-archive.com/?u=2eff8714011ff4bfba18a0704&id=d75dc96e7f">https://us13.campaign-archive.com/?u=2eff8714011ff4bfba18a0704&id=d75dc96e7f</a>

Impact Statements

The identification of two distinct virulence loci (plant toxin and reactive sulfur tolerance genes) that contribute in two distinct ways to the ability of the bacteria Pantoea to cause center rot has revolutionized our understanding of the pathogen. We believe the distribution of these virulence loci in the Pantoea population will serve as an excellent indicator for potential risk of post-harvest disease and yield loss. Diagnostic assays based on these loci are being developed to aid onion growers in their management decisions. Studies on the roles of plant toxin and reactive sulfur tolerance in the virulence of Pantoea will provide new avenues for the development of novel management strategies and potentially for the development of resistant onion cultivars.

Date of Annual Report: 09/21/2019

Report Information

Annual Meeting Dates: 07/24/2019 - 07/24/2019
Period the Report Covers: 10/01/2018 - 01/01/1970

Participants

Participants Attachment:

W3008 Final Report Draft.docx

Brief Summary of Minutes

The Chair Beth Gugino called the meeting to order at 10 AM.

Welcome and Introductions, W3008 status, 2020 annual report, comments from W-3008 Advisor Steve Loring

W-3008 Committee for 2019:

Beth Gugino, Chair - bkgugino@psu.edu

Bhabesh Dutta, Vice-Chair - bhabesh@uga.edu

Peter Rogers, Secretary - peter.rogers@vegetableseeds.basf.com

Christy Hoepting, Past-Chair - cah59@cornell.edu

Comments from Steve Loring via email communication to Beth Gugino: Not much to report from the national view. Most of you know that NIFA is moving to Kansas City despite objections from the land-grant system. Watch for RFPs in big areas and be prepared to collaborate.

Project level – State reports will be due to Bhabesh so that he can compile the annual report due in NMISS 60 days from this meeting in mid-September. Reminder about the importance of impact statements no just reports of activities.

State Report Summaries:

10:10 am Colorado – Mike Bartolo

Onion acreage reduced from 12,000 to 4000 A over recent years; labor contributing factor

Effort is being made to maintain the onion line Colorado 6

Thaddeus Gourd – conducted the 2019 northern Colorado onion variety trial with Sakata Farms

Created a planter box insert to convert a commercial Milton planter into a small plot planter

Tyler Mason – focusing on organic weed management. Testing capric acid for weed control acting as contact herbicide, available for organic farmers

Hiring a new insect vector virologist – Punya Nachappa

The Colorado Fruit and Vegetable Growers Association is very active and held their annual meeting in Denver

10:20 am Georgia - Bhabesh Dutta

Vidalia onion in GA has a $160 M farm gate value; grown on 11,000 A in 21 counties

Center rot and sour skin are major problems

Botrytis leaf blight was widespread but not severe in 2019. Conducted a fungicide trial – Omega 500 was superior, Rovral did not work well; program with Luna tranquility or Omega 500 or Miravis prime in rotation with Inspire Super and Scala were effective; growers rely on phosphites (ProPhyt vs Kphite) – ProPhyt was significantly better

In 2018 downy mildew was only at research station but in 2019 it was more widespread but only moderate– conducted a fungicide trial on commercial farm – Orondis Ultra + Bravo alt with Omega 500 + Bravo were effective.

10:30 am Idaho – Mike Thorton

Treasure Valley – 22,000 A and over 75% of growers have adopted drip irrigation compared to traditionally used surface irrigation

2019 crop – Wettest April in record. Herbicide issues and bulb mites caused low stands;

Three research groups working on onion
- James Woodhall – is spore trapping with a Burkhart sampler for Botrytis; conducting soilborne pathogen assays for soil pathogen through a Specialty Crop Block Grant looking at Fusarium proliferatum and Setophoma terrestris
- Brenda Schroeder – Working on Fusarium proliferatum and evaluating onion variety lines for resistance
- Mike Thorton – Evaluating use of Fontelis for Pink root through the drip; using remote sensing to map where pink root is most severe during the field in season to make management decisions later in the year; working on long-term storage issues caused by Botrytis alli or Fusarium proliferatum - prior to 2015 the issue was primarily Botrytis, in 2015-16 Fusarium became more problematic; most important issue seems to vary by year

10:40 am New Mexico - Chris Cramer

Good year for onion production; June 10^th, unusual 2 to 3 in. of rainfall with 60°F temperature flanked by hot days with temperature over 100 °F.

Working on breeding resistance to Fusarium bulb rot; application of mature bulb screening technique to 7 populations for FBR R (SD Granex types).

Also breeding resistance to Thrips and IYSV – germplasm evaluated (waxy vs glossy leaves); 4 Semi Glossy, 1 Glossy, and Rumba waxy. Measurements on same 10 plants per plot during the season were made

Trials arranged in a split-plot design evaluating the effect of irrigation treatments (well-watered vs limited water) with water status as whole plot and germplasm as split plot

10:50 am New York - Christy Hoepting and Brian Nault

7600 A in muck onion production

2019 was one of coldest and wettest springs; delayed planting and many acres planted later than desired; some acreage didn’t get planted (maybe 10%). Uneven stands due to planting wet but total stand was good

EverGol Prime - new smut seed treatment

Growers are getting good weed control, but injury was higher than usual

Last day of spring got 3 to 7 in. of rain in Oswego so there were 2500 A underwater, but plants recovered

End of June – finally warmed up – low disease and thrips pressure

Soilborne diseases –issues with PR and FBR, more than ever in 2018.
- Lead to 2019 trial to evaluate 17 in-furrow fungicides and biologicals treatments for control of pink root and Fusarium basal rot

Stemphylium and BLB/fungicide programs and timings were examined. Conventional and organic products were evaluated. Determined if Bravo interferes with performance of translaminar fungicide as it does with translaminar/systemic insecticides

Bacterial bulb rot trials, 2^nd year; 9 varieties tested
- No crop response to N last year up to 135 lbs/A. This year 10-30-60 lb/A was evaluated

Onion maggot projects –Evaluating relationships between onion maggot adult activity and onion maggot damage
- Identify how Spinosad protected onion seedlings from onion maggot if not systemic?
- Novel insecticide seed treatments
- Onion maggot transplanted onions – dipped with Entrust – interest in using plant tape and plug transplants
- Also entomopathogenic nematodes for OM

Onion Thrips projects_ Evaluating IPM tactics for Thrips & IYSV control, along with Stemphylium on organic onions

Allium leaf miner project with Penn State; Allium leaf miner (ALM) control, testing conventional insecticides and OMRI-listed products. Insecticide program for ALM control in conventional and organic onions
- Evaluating color patterns of sticky cards for monitoring of adults. Yellow does not work
- Degree-days study to determine emergence predictability

11:00 am Pennsylvania – Beth Gugino

Similar challenges with weather and crop emergence as NY;

Spanish cultivar Candy main cultivar grown. Transplants from AZ mainly. Planting March-mid April. Wet season as in NY.

Simply sweet onions branded in Pennsylvania. Ninety onion growers with 125 A. Growers are concerned that variety Candy will be not be available for sale. Testing variety Sunbelt Sweet that showed high susceptibility to bacterial pathogens. Panteoa (P. ananatis or P. agglomerans?) concerned as causal agents.

2019 IR-4 trial (same as Lindsay in WA) and timing inoculation method trial.

11:10 am Texas – Subas Malla

Conducted thrips studies in 2017-18 and 2018-19; studying population and insecticide treatments; no IYSV detected in 2018-19.

2018-19 downy mildew and Stemphylium nursery were used for germplasm screening in organic system

Hailstorm injury in past year followed by secondary bacterial infection

Evalauting NDVI correlation with disease in field with plant height, leaf number, and neck diameter

Onion seed production failed in 2017 but was able to produce a crop in 2018

Winrhizo software to characterize root in field with pink root vs. not

11:20 am Utah - Dan Drost

Acreage down 10-15% to 1800 A

90% acreage went in after 20^th April – every week plant later than Apr 15^th, lose 10% yield (stopped planting May 1^st). Spring rain excessive so ground prep was problematic

Establishment was good considering the poor seed bed condition; plant to plant variability was horrendous some at 3 leaf and some at 10 leaf stage – not sure what was contributing to non-uniformity

Growers are heavily invested in drip irrigation went from 5% on drip to 75% on drip – but growers still have a furrow irrigation mentality when using drip – once per week for 24 h (some only have access to water once per week) – so investing in ponds to hold water that can be used to meter out drip – state is invested in making this work – growers switching to drip also need to consider changing other practices like seed density – the spacing is wide so getting too many colossal and super colossal using furrow irrigation seeding rates

11:30 am Washington - Tim Waters and Lindsey du Toit

Columbia Washington basin - cold late spring with snow – delayed planting but things are looking good despite some hail storms

Downy mildew in bulb crops due to weather which is atypical usually see it in the seed crop

The onion alert system has been successful with 646 subscribers (started in 2007) – modeled off the potato alert system

Contributing to SCRI project to screen germplasm for resistance to Fusarium and Pink root

Fusarium basal rot trial using Fontelis to evaluate disease control

Cultivar trial – 40 cultivars – Aug 29^th field day

Thrips project with Tim Waters

SCRI project on bacterial disease, 4 million was recommended for funding. Not official yet. Twenty four people, 12 states and 1 other country. Many growers will be involved on this project.

Organizational Items

11:30 am Election of new officers – revisit discussion from last year

Two nominations last year resulted in Peter Rogers serving as Secretary in 2019 and David Burrell from National Onion Labs will serve in 2020. We welcome David Burrell to the W3008 Officers Committee for 2020.

11:35 am Discussion of 2020 annual meeting location & date

There was extensive discussion about where and when to host the meeting. The first option would be to hold it in conjunction with the 2021 Southeast Fruit and Vegetable Convention in Savannah, GA. Beth Gugino will check with Steve Loring to see if this is allowable since it does not fall in the 2020 calendar year. The second option is to have an airport meeting in Atlanta in fall 2020. Bhabesh Dutta and David Burrell will serve as local arrangements in either case.

12:00 pm Adjourn

Accomplishments

Objective 1. Evaluate onion germplasm for resistance to pathogens and insects. New Mexico (Cramer): In October 2018, onion bulbs were placed on the first and last bed of the study and at the front and back borders of the field study. In addition, seed of ‘NuMex Freedom’ was sown at the same time on every seventh bed to ensure that thrips are spread throughout the field the following year. On 7 January 2019, seed of four NMSU germplasm lines and ‘Rumba’, an IYS-susceptible cultivar was sown in flats at the Fabian Garcia Science Center in Las Cruces, NM. Ten plants were randomly-selected from each plot and identified with a plastic label. Starting on 8 May 2019 and four additional times two weeks apart, the number of adult and juvenile thrips were counted from each of the ten plants from each plot. On 5 June 2019, the severity of Iris yellow spot symptoms was rated for each of the ten plants. These ratings were repeated for two additional times two weeks apart. At 8, 10, and 12 weeks after transplanting, plants of ’Rumba’ possessed more juvenile and total thrips than plants of the four NMSU germplasm lines. At 12, 14, and 16 weeks, plants of ‘Rumba’ exhibited more severe Iris yellow spot disease symptoms than plants of all other four entries. New York (Nault, Hoepting, Pethybridge, Hay): Over the past two years, a study was conducted to evaluate multiple tactics to manage onion thrips in organically produced onion. Two mulch types (reflective and white), two semi-glossy “thrips-resistant” cultivars (‘Rossa di Milano’ and B5336 x B5351) and one waxy “thrips-susceptible” cultivar (‘Bradley’), and two insecticide treatments (Entrust and untreated control) were evaluated. Total numbers of thrips larvae were higher on onions grown on white mulch than on reflective mulch in 2019, but the opposite was true in 2018. In both years, more thrips were encountered in the Bradley cultivar than in the thrips-resistant cultivars, and more in untreated control plots than in Entrust-treated plots. In 2018, marketable bulb yields were highest on onions grown on reflective mulch compared with white mulch, higher in Bradley and B5336 x B5351 cultivars than Rossa di Milano, and higher in Entrust than the untreated control. Overall, the most effective tactics for reducing onion thrips infestations while maintaining acceptable marketable yields were to use either Bradley or B5336 x B5351 cultivars, reflective mulch and Entrust. Over the past two years, a study was conducted to evaluate the effect of onion variety and nitrogen on bacterial bulb rot.  In 2018 and 2019, two trials were conducted in commercial onion fields in ‘muck’ soil in Elba and Oswego, NY. Seven onion varieties were compared across 37, 100 and 150 lb/A of nitrogen.  Artificial toothpick prick and backpack sprayer inoculation techniques with Pantoea ananatis and P. agglomerans were also included.  In 2018, Nitrogen had no effect on yield or bacterial bulb rot, so data per variety was pooled across nitrogen treatments. Bacterial bulb rot pressure was moderate with natural infection levels greater than 10% and 25% in Oswego and Elba, respectively.  In both trials, Trailblazer had the least natural bulb rot, which was not significantly different from Saddleback and Braddock, while Red Wing had the most natural bulb rot, which was not significantly different from Montclair, Pocono and Catskill. Varieties that had the most natural bulb rot also had the largest neck diameter, while the varieties with the smallest neck diameter had the least bulb rot. Although there were no significant differences among varieties for bulb rot when they were artificially spray-inoculated, incidence of bulb rot was 16 to 40% higher than natural infection for all varieties except Red Wing. Artificial prick-inoculation increased bulb rot over natural infection in all varieties by 24 to 300% and differences among varieties for incidence of bulb rot was the not the same as natural infection.  For example, Red Wing did not have the highest level of bulb rot with artificial prick-inoculation. Instead, Red Wing was not significantly different then Trailblazer, which again had the least bulb rot.  In both trials, Montclair and Braddock were two of the top-yielding varieties, while the variety most tolerant to bulb decay, Trailblazer and the variety most susceptible to bulb rot, Red Wing had the lowest yields. Overall, these onion varieties were consistent in their relative susceptibility to bacterial bulb rot, with incidence increasing with days to maturity and neck diameter. Artificial inoculation techniques demonstrated promise for increasing disease incidence.   Oregon (Reitz, Dung and Shock): Thrips and IYSV are the most important pests of onions grown in the Treasure Valley of eastern Oregon and southwest Idaho. As part of ongoing onion variety trials conducted at the Malheur Experiment Station, varieties are rated during the season for thrips damage and severity of iris yellow spot. In 2018 trials, IYS was present in all cultivars, but at relatively low levels. Thrips feeding damage varied among cultivars. Red cultivars had greater levels of thrips feeding damage than with yellow cultivars. Within each color, there were significant differences among cultivars in terms of thrips feeding damage. Texas (Malla): During 2018-19 season, foliar disease complex of downy mildew, botrytis leaf blight and Stemphylium leaf blight was observed in onion. The foliar disease severity was higher in the seed production and organic nursery. The higher foliar severity also resulted in higher percentage of bulb rot. A total of 23 Texas A&M (TAM) lines were evaluated for yield in the organic system. The germplasm showed variation for foliar disease resistance. The foliar disease severity was rated on a scale of 0 to 9, where 0 = immune and 9 = highly susceptible. TAM Experimental (Expt) #50084 and TAM Expt #31034 had the least disease with a severity rating of 2, whereas TAM Expt #43053 and TAM Expt #43044 had the highest disease with a severity rating of 8. Elite yield trial, consisting of 23 TAM elite germplasm and 18 commercial checks, was evaluated for pink root resistance in the conventional system. The germplasm were evaluated in the pink root screening nursery, where the germplasm had been evaluated for pink root resistance for the third consecutive year. Pink root was rated during harvest on a percentage of root infection where 0% = immune and 100% = highly susceptible. Yellow H6 had the least pink root severity (10%) followed by TAM Expt #31034 (17.5%). TAM Expt #34036 had the highest disease severity of 85%. Advanced germplasm from TAM were also evaluated for pink root resistance. A total of 36 germplasm (23 advanced lines from TAM and 13 from commercial checks) were screened for pink root resistance in the nursery. TAM Expt #41066 had the least disease severity (7.5%) followed by TAM Expt #50020-2 (12.5%), whereas TAM Expt #40017 had the highest pink root severity (70%). A total of 220 TAM preliminary lines were also evaluated for pink root resistance in the preliminary yield trial in the pink root screening nursery. Ten germplasm (TAM Expt #: 33015, 40026, 40027, 40060, 40061, 40066, 40067, 90519, 92007 and 92021) had the pink root severity of 5% indicating that the germplasms have resistance against the disease. Washington (du Toit, Waters, Pappu): The Washington State University onion cultivar trial was planted in May 2019 near Connell, WA, with three replicate plots of each of 47 cultivars submitted by various onion seed companies. The plots were evaluated regularly for diseases and pests. In August, the plots were rated for percentage tops down as well as the severity of powdery mildew, a disease not often seen in the Columbia Basin but which showed up more than normal during the 2019 season with some significant differences observed among the cultivars in this trial. Bulbs will be harvested from the plots in September to assess yield, and 50 bulbs/plot will be placed in storage to evaluate for storage quality and storage rots in February 2020. Several cultivars and breeding lines were evaluated for their response to Iris yellow spot virus infection under field conditions. Symptom severity, final disease incidence and relative virus levels are used to as criteria to identify cultivars with virus resistance or tolerance.   Objective 2. Investigate the biology, ecology and management of onion thrips and other pests. New York (Nault, Hoepting, Pethybridge, Hay): A three-year experiment was conducted to identify an insecticide and rate that most effectively reduces a very high onion thrips infestation. Minecto Pro (abamectin plus cyantranilprole), Exirel (cyantraniliprole) and Radiant SC (spinetoram) were evaluated at their lowest and highest recommended rates. All treatments were applied twice one week apart beginning when the thrips larval density was 3-4 per leaf. Extremely high infestations occurred only in one of the three years of the study (2018). In that study, one week after the second application, only Radiant at 10 fl oz/A significantly reduced the thrips density to below 2.2 larvae per leaf (economic injury level).  Densities of larvae in the Minecto Pro and Exirel treatments were all above 4 larvae per leaf and 2.7 per leaf in the low rate of Radiant. The high rate of Radiant SC should be considered the best option for providing the greatest reduction of a high thrips infestation. In a two-year study, the best combinations of OMRI-listed insecticides and adjuvants were evaluated for managing onion thrips in organically produced onions. Four insecticides (Azera, Entrust, Neemix and PFR 97) and three adjuvants (M-Pede, Nu-Film and Trilogy) were applied weekly. Entrust co-applied with either M-Pede or Trilogy consistently provided the best thrips control. Insecticide seed treatment performance was evaluated for managing very high onion maggot infestations in 2019. Onion maggots killed nearly 100 percent of the plants in the fungicide-only control. Similarly, the percentage of plants killed in the Lorsban Advanced drench treatment was also near 100 percent. The seed treatment Regard significantly reduced the percentage of maggot damage compared with levels in the control and the Lorsban treatment, but still suffered over one-third of the plants being killed by maggots. The least amount of onion maggot damage occurred in BASF 450, which only had 5 percent plants killed by maggots. BASF 450 will be considered for future research as it has tremendous promise as an excellent new insecticide for onion maggot control. Insecticides that would effectively protect Allium crops from damage caused by the new invasive Allium leafminer (ALM) were also evaluated in 2018. Conventional and OMRI-listed products were applied weekly on bulb onion, leek and scallion. Pressure was moderate to high in the experiments. The most consistent and best performing conventional treatments included Scorpion (dinotefuran), Exirel (cyantraniliprole) and Radiant (spinetoram), while the best performing OMRI-listed product was Entrust (spinosad). Oregon (Reitz, Dung and Shock): Ongoing insecticide efficacy trials demonstrated effectiveness of new insecticide use programs to better manage thrips and IYSV in the Treasure Valley. As part of a USDA-SCRI grant (Pappu et al. Development and Delivery of Integrated Management Packages for the Most Serious Pest and Diseases Threatening the US Allium Industries), we are conducting field trials to assess how nitrogen fertilization combined with insecticide management programs based on sampling thresholds or scheduled applications affect thrips and iris yellow spot.    Field trials conducted in 2018 and 2019 demonstrate a decline in the efficacy of methomyl against thrips populations in the Treasure Valley. A regional pest-monitoring program provided information to growers on seasonal pest trends, including changing patterns in thrips and IYS incidence in the Treasure Valley. Washington (du Toit, Waters, Pappu): Previous study by the Walsh lab at the WSU IAREC in Prosser documented the universal incidence of resistance to pyrethroids among onion thrips populations in Washington State. Another class of insecticide commonly used for thrips control in onions is the carbamates, i.e., oxamyl (Vydate) and methomyl (Lannate LV). Methomyl and oxamyl are often applied multiple times to individual fields over the course of the growing season, and both have been used on onions for over 25 years. We evaluated the tolerance of onion thrips to field doses of oxamyl and methomyl. Commercial fields with a history of oxamyl and methomyl use contained thrips populations that were far less susceptible to those insecticides than thrips from fields where these insecticides had not been used. This demonstrated that resistance is present in thrips populations in the Columbia Basin of Washington State. We have confirmed again that when seedcorn maggot is present as a pest in a field, seed treatments can increase plant stand and, therefore, yield and quality of onion crops. Commercial producers are now aware of this technology and adoption is widespread. In conventional crops, we have shown that 4 active ingredients (dpinetoram, methomyl, abamectin, and cyantraniliprole) are highly effective for control and one (spirotetremat) is somewhat effective. Producers now need better information on the timing and appropriate sequences of application of these products. Organic producers still have limited options. One active ingredient (spinosad) has been shown to be effective, and the efficacy is enhanced with two different tank mix partners (azadiractin and a Burkolderia sp). Additionally, we determined that three organic products applied alone were ineffective for thrips control (Celite, Venerate, and AzaDirect).   Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens.   California (Putnam): Field trials were initiated in Holtville, CA (October 2018) and Brawley, CA (November 2018) to evaluate the utility of weather-based models to schedule fungicide applications to manage downy mildew of onions for processing. A weather station was established within the Holtville trial to measure standard parameters at a height of 2 m, plus temperature, relative humidity, and leaf wetness within the plant canopy. A weather station was not installed at the Brawley location due to slow crop development. None of the models were triggered at any time during the course of the monitoring period. Two applications of the standard calendar-based treatment were made based on subjective assessments of weather conditions. Downy mildew was not observed in the both trials, consistent with overall very low downy mildew pressure in the California desert in the winter of 2018-2019. Georgia (Dutta, Kvitko): We identified susceptible growth stages (first leaf senescence, bulb initiation and bulb swelling) of onion to P. ananatis-bulb infection. Multi-year field trials were conducted to evaluate if onion growth stage directed chemical protection can reduce center rot bulb incidence. Onion plants were protected with agrichemicals at all three growth stages. The field plots were aggressively protected with insecticides for thrips control. The results indicate that Kocide 3000 or Kocide 3000 with Actigard when applied at either bulb initiation or bulb swelling stage can significantly reduce disease incidence in bulbs compared with Actigard only and the untreated control. In 2019, field trial was designed to evaluate the growth-stage directed spray in conjunction with or without a thrips management program. For treatments where thrips management program was not utilized, non-bactericide treated check had significantly higher center rot incidence in bulb and also resulted in lower marketable yield compared to other treatments. Treatments with either Agrititan (nano-formulation of TiO2; 1% v/v) or Kocide 3000 (1.5 lb/A)+Agrititan (1% v/v) had significantly lower center rot bulb incidence and higher marketable yield compared to other treatments. For treatments where thrips management program was followed, non-bactericide treated check plots had significantly higher center rot incidence in bulb and lower marketable yield compared to other treatments. Treatment with Kocide 3000+Agrititan had significantly lower center rot bulb incidence and higher marketable yield compared to other treatments. Based on comparisons of the complete DNA sequences of onion virulent and non-virulent strains, two clusters of genes were identified that were strongly correlated with the ability of a Pantoea strain to cause disease on onion. We generated strains lacking these genes to determine what roles they play in center rot. The first cluster of disease-associated genes, HiVir, are required for Pantoea to cause damage to both onion leaves and bulbs and are consistent with genes that would allow the bacteria to produce a plant herbicidal toxin. The second cluster of disease-associated genes, alt, allow the bacteria to tolerate the noxious sulfur compounds released by damaged onions. We have found that both gene clusters combined are required for Pantoea to colonize onion bulbs. We have used these two disease-associated gene clusters as the basis for the development of simple diagnostic assays. The red onion scale clearing assay, which can identify strains that carry the HiVir toxin cluster, and a multiplex PCR assay that can identify both HiVir and alt cluster. These assays can readily distinguish disease-causing Pantoea from harmless environmental strains as well as identify strains that may pose an increased risk of post-harvest onion bulb disease. New York (Nault, Hoepting, Pethybridge, Hay): Two projects on Stemphylium leaf blight (SLB) have been completed in 2019 (NY Farm Viability Institute, Specialty Crop Block Grant SCG 16-008 and NIFA CPPM NYG-625591).  Stemphylium leaf blight has become a dominant foliar pathogen of onion in NY and phylogenetic analysis has confirmed the species involved as S. vesicarium.  A large proportion of the S. vesicarium population collected from onion around NY exhibited insensitivity in the laboratory to active ingredients in the FRAC 11 group (azoxystrobin and pyraclostrobin) and FRAC 7 (boscalid) group.  On the basis of this, and a recently observed decline in efficacy in the field (see below), the use of fungicides based solely on these active ingredients has been curtailed by the onion industry in NY.  Laboratory tests indicated a moderate level of insensitivity in the S. vesicarium population to FRAC 9 (cyprodinil and pyrimethanil).  This, coupled with observations of only moderate efficacy of fungicides based solely on these ingredients in the field suggests the development of fungicide resistance in this group.  FRAC 9 fungicides remain in use against SLB, often in mixtures with other FRAC groups, but will continue to be monitored for evidence of field failures against SLB.  There was little or no evidence of fungicide insensitivity to FRAC 7 (fluopyram and fluxapyroxad), FRAC 3 (difenoconazole), or FRAC 2 (iprodione) active ingredients in the laboratory, and products containing these ingredients currently remain the basis of fungicide management strategies for SLB in NY.  Ongoing sensitivity testing in 2019 has indicated further shifts in fungicide sensitivity.  Two field trials confirmed leaf debris from preceding onion crops was a significant source of inoculum of S. vesicarium into the following onion crop, and methods to encourage decomposition of debris over winter reduced disease incidence in the following crop early in the season.  S. vesicarium was detected rarely in weeds within and surrounding fields in Elba, NY soon after planting, indicating that weeds could be a source of inoculum, but may not be a significant source.  S. vesicarium was not detected in commercial organic seed lots of 13 varieties of onion harvested in 2016 (n = 1300 seeds), or 15 varieties harvested in 2017 (n = 1500 seeds). A field trial to screen OMRI listed products against SLB, identified Badge X2 and Kocide 3000-O as having moderate efficacy, with significantly lower disease severity than the non-treated control in a situation of moderate disease pressure.  Oso, which is currently undergoing consideration for OMRI listing, also provided a significant, but moderate level of control. Oregon (Reitz, Dung and Shock): White rot trials were conducted in Tulelake, CA and western Fresno County, CA on onion and garlic, respectively.  Main plot treatments consisted of biostimulants that were shank-injected in the spring and/or fall prior to planting. Tebuconazole was applied in-furrow as a split-plot treatment at both sites at planting. At the Tulelake site, the greatest reductions in sclerotia populations were observed in plots treated with garlic oil in the spring and fall, DADS, and garlic oil (spring) + allyl isothiocyanate (fall). In-furrow applications of tebuconazole significantly increased onion stand and reduced late season onion leaf dieback and AUDPC values compared to the no-fungicide control. Garlic oil (spring) + allyl isothiocyanate (fall), garlic juice (spring), and garlic oil (spring and fall) exhibited the highest yields of disease-free onion bulbs. In-furrow applications of tebuconazole increased disease-free onion yield compared to the no-fungicide control. At the Fresno site, in-furrow applications of tebuconazole increased total garlic yield and decreased the number of garlic bulbs with severe disease symptoms. Sclerotia populations increased greatly from onion and garlic planting to harvest at both sites in plots not treated with an in-furrow application of tebuconazole, suggesting that tebuconazole may help prevent the buildup of sclerotia in fields after an Allium crop. Pennsylvania (Gugino): During the 2019 production season, two onion center rot trials were conducted. One was in partnership with IR-4 to evaluate the performance of 14 commercial as well as experimental products for the management of center rot of onion caused by P. agglomerans and P. ananatis (considered a pest problem without a solution by IR-4). The treatments plus a non-treated control were evaluated in a randomized complete block design with four replicates. Applications were initiated prior to toothpick inoculation of the pathogens. Data on disease severity as well as harvest data were collected. A subset of marketable onions from each treatment has been placed in storage for evaluation in mid- to late October. The data collected to-date is in the process of being analyzed. A second replicated multi-factorial center rot (P. agglomerans and P. ananatis) research trial was established in partnership with the Pennsylvania Vegetable Growers Association to evaluate several bacterial inoculation methods (three methods) and inoculation timing (three plant growth stages). The goal being to identify a consistent inoculation method and time to inoculate the plants to achieve uniform disease distribution throughout plots in the field. Data on disease severity as well as harvest data were collected and are in the process of being analyzed. Texas (Malla): Trials were conducted to correlate Normalized Difference Vegetative Index (NDVI) , foliar disease severity and onion marketable yield A correlation between foliar disease rating and marketable yield was high (r = -0.80) in the elite yield trial in the organic system. A correlation was also high (r = -0.76) between NDVI and marketable yield. In the elite yield trial in pink root screening nursery (conventional system), a lower correlation (r = -0.27) was observed between pink root severity and marketable yield, but a higher correlation (r = 0.72) was observed between NDVI and marketable yield. The correlation between NDVI and pink root severity was -0.53. High-throughput phenotyping (HTP) using NDVI resulted in moderate to higher correlation among NDVI, disease severity and marketable yield. Washington (du Toit, Waters, Pappu): A field trial funded by the IR-4 Minor Crops program was planted in Pasco, WA in spring 2019 to evaluate the efficacy of 14 treatments (products) for control of bacterial leaf blight and bulb rots caused by Burkholderia gladioli pv. alliicola and Pantoea agglomerans, using a randomized complete block design with four replicate plots. Products applied to main plots (each 2 beds wide) included ManKocide, Kocide 3000-O, Champ WG, Oxidate 2.0, Kasumin 2L (at 2 rates), Nano-magnesium oxide, GWN 10120, SP8010 (alone with tank-mixed with Kocide 3000-O or SP2700), Lifegard WG, and Instill. Each product was applied three to seven times at weekly or 5-day intervals, depending on the label restrictions. Split plots (each a single bed x 15 feet) were either inoculated twice with the two bacterial pathogens or not inoculated (water), using a backpack sprayer to apply inoculum. The final application was completed the last week of August. Plots were rated weekly for the incidence and severity of foliar bacterial symptoms. Bulbs will be harvested in September, with 50 bulbs cut and rated for bacterial rots at harvest and another 50 bulbs placed in storage for evaluation of storage rots in February 2020.   Objective 4.  Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management. Georgia (Dutta): Two trainings for county extension agents and professionals in Georgia, 10 Georgia producer trainings, and 3 national or regional invited extension presentations were conducted to disseminate updated information on onion disease management. These meetings have covered onion disease management through transfer of information and technology in Georgia. Pennsylvania (Gugino) Research results were disseminated through one-on-one interactions with growers as well as participation in the 2019 International Allium Convention in Madison, WI in July. Washington (du Toit, Waters, Pappu): Newsletter articles were written and distributed to >600 subscribers, mostly in the Pacific Northwest USA, via the WSU Onion Alerts (<a href="https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792">https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792</a>). Time-sensitive topics covered in seven articles between May 30 and August 21 of 2019 included downy mildew, fungicides, thrips, nematodes, iris yellow spot, irrigation, and powdery mildew. A grant proposal titled ‘Stop the rot: Combating onion bacterial diseases with pathogenomic tools and enhanced management strategies’ was submitted to the USDA NIFA Specialty Crops Research Initiative (SCRI) in May 2019. The proposal was led by Lindsey du Toit from WSU, with 5 co-PIs, 18 other collaborators from 12 states in the USA and one other country, with guidance/input from 12 onion growers/stakeholders serving on the project Stakeholder Advisory Panel. The proposal was recommended for funding at $4.0 million with matching funding of $4.2 million. The 4-year project will start in fall 2019. New York (Nault, Hoepting, Pethybridge, Hay): 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. Details of these interactions are included in the Presentations section. Oregon (Reitz, Dung and Shock): We published an updated IPM Strategic Plan for Treasure Valley Onions that documents the current status of pest management for the industry and its critical needs (Murray, Reitz and Jepson. 2019. An Integrated Pest Management Strategic Plan for Treasure Valley Onions: Oregon and Idaho). The IPMSP will be available through the Western Region IPM Center <a href="http://westernipm.org/">http://westernipm.org/</a>.

Publications

Journal articles: Hay, F., Sharma, S., Hoepting, C.A., Strickland, D., Luong, K. and Pethybridge, S.J. 2019. Emergence of Stemphylium Leaf Blight of Onion in New York Associated with Fungicide Resistance. Plant Disease, (ja).   Knerr, A.J., Wheeler, D., Schlatter, D., Sharma-Poudyal, D., du Toit, L.J., and Paulitz, T.C. 2019. Arbuscular mycorrhizal fungal communities in organic and conventional onion crops in the Columbia Basin of the Pacific Northwest USA. Phytobiomes 2:194-207.   Leach, A.B., Fuchs, M. Harding, R.S. and Nault, B.A. 2019. Iris yellow spot virus prolongs the adult lifespan of its primary vector, onion thrips (Thrips tabaci). Journal of Insect Science 19(3):1-4. <a href="https://doi.org/10.1093/jisesa/iez041">https://doi.org/10.1093/jisesa/iez041</a>   Leach, A.B., Hay, F., Harding, R.S. Damann, K.C. and Nault, B.A. 2019. Relationship between onion thrips (Thrips tabaci) and Stemphylium versicarium in the development of Stemphylium leaf blight in onion. Annals of Applied Biology (in press).   Leach, A.B., Hoepting, C.A. and Nault, B.A. 2019. Grower adoption of insecticide resistance management practices increase with extension-based program. Pest Management Science 75:515-526.   Murray, M.K., Reitz, S. and Jepson, P. 2019. An Integrated Pest Management Strategic Plan for Treasure Valley Onions: Oregon and Idaho. Western Region Integrated Pest Management Center.  (in press)   Moretti, E.A., Harding, R.S., Scott, J.G. and Nault, B.A. 2019. Monitoring onion thrips (Thysanoptera: Thripidae) susceptibility to spinetoram in New York onion fields. Journal of Economic Entomolology. 112(3):1493-1497.   Rahimi, S., Hseih, S., Renlin, Xu., Avis, Tyler, A., Smith, D., Dutta, B., Gitaitis, R. and Tambong, J. 2019. Pathogenicity and a TaqMan real-time PCR for specific detection of Pantoea allii, a bacterial pathogen of onions. Plant Disease (in press).   Peer-reviewed technical reports: Dutta, B., Riner, C., Edenfield, J., Tyson, C., Tanner, S., Williams, Z., Shirley, A. and Earls, C. 2019. Evaluation of onion growth stage directed chemical applications on center rot incidence in onion bulbs in Georgia, 2018. PDMR13:V020.   Dutta, B., Edenfield, J., Tanner, S., Williams, Z. and Riner, C. 2019. Evaluation of fungicides to manage Downy mildew in Toombs County, Georgia, 2018. PDMR 13:V019.   Dutta, B., Foster, M.J., Donahoo, W.M., Coolong, T. and Riner, C. 2018. Evaluation of a pre-plant fumigant and a post-plant fungicide on the control of Fusarium wilt of watermelon in Toombs County, Georgia 2017. PDMR 12:V141.   du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Brouwer, L.R., Waters, T.D. and Darner, J. 2019. Effects of the arbuscular mycorrhizal fungi inoculant Mykos Gold Granular on pink root and yield in commercial onion bulb crops near Irrigon, OR, 2017. Plant Disease Management Reports 13:V008.   du Toit, L.J., Derie, M.L., Holmes, B.J., Morgan, P., Brouwer, L.R. and Waters, T.D. 2019. The influence of soil phosphorus levels on onion root colonization by mycorrhizal fungi from commercial inoculants, 2017. Plant Disease Management Reports 13:V009.   du Toit, L.J., Derie, M.L., Holmes, B.J., Henrichs, B.A., Winkler, L.R., Waters, T.D. and Darner, J. 2018. The effects of arbuscular mycorrhizal fungal inoculants on pink root and yield in an onion crop near Paterson, WA, 2016. Plant Disease Management Reports 12:V102.   Extension publications: Dutta, B., Schmidt, J., and Johnson, W.C.  2019. Challenges faced by the organic and the organic-transition Vidalia onion growers in Georgia. In: VSC News Magazine. April 2019.   Hayden, Z.D., Leach, A. and Nault, B. 2019. Nitrogen: Is less more? Studies in Michigan and New York highlight potential for reducing nitrogen rates on muck soils. Onion World  35 (5):14-16.   Hoepting, C. 2019. Control of onion downy mildew when disease pressure is high.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(15):3-5.   Hoepting, C. 2019. Onion diseases of August.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 16(17):6.   Hoepting, C. 2019. Stretching onion fungicide spray programs to preserve useful longevity of FRAC 3/7.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(17):3-4.   Hoepting, C. 2019. News on fungicide resistance in New York and consequent changes to 2019 fungicide recommendations for Stemphylium and Botrytis leaf blight in onion.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(12):6-8.   Hoepting, C. 2019. Control of onion downy mildew with fungicides.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(10): 9.   Hoepting, C. 2019. Scouting tips for identifying downy mildew in onion.  Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(10):8.   Hoepting, C. 2019. My big fat onion variety nitrogen rot project.  In: Proceedings of the 2019 Empire State Producers Expo, Syracuse, NY: 14-17 January, 2019. Online: <a href="http://www.hort.cornell.edu/expo%20/pdf/20190116-1-hoepting.pdf">http://www.hort.cornell.edu/expo /pdf/20190116-1-hoepting.pdf</a>.   Hoepting, C. and Nault, B. 2019. 2019 Cornell guidelines for onion thrips management in onion. Cornell Cooperative Extension, Cornell Vegetable Program Veg Edge. 15(14): 8-9.   du Toit, L. and Yorgey, G. 2018. Onion stunting after cereal cover crops. Page 6. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Page 7. Efficacy of fungicide applications to manage onion stunting caused by Rhizoctonia spp. Pages 7-8. In: Strip-tillage for onions and sweet corn, Lorin Grigg. Farmer to Farmer Case Study Series on Increasing Resilience among Farmers in the Pacific Northwest. Washington State University Extension PNW702.   Popular periodicals: Iglesias, L. and Nault, B. 2019. Tackling thrips in organic onions. Onion World 35(5): 7-9. Winkler, L., du Toit, L., and Waters, T. 2019. Mycorrhizal inoculants: Yea or nay? The effects of mycorrhizal        inoculants on onion crops in the Columbia Basin. Onion World Feb. 2019:10-14. https://issuu.com/columbiamediagroup/docs/feb_2019_onion_world_web?e=34405975/67413329   Other Activities   <ol> <li> Abstracts and Papers at International Professional Meetings</li> </ol>   du Toit, L.J., Waters, T.W., Derie, M.L. and Brouwer, L. 2019. Can onion growers benefit from mycorrhizal inoculants? 2019 combined meeting of the National Onion Association, National Allium Research Conference and International Allium Research Symposium, 24-27 July, 2019, Madison, WI. (Abstract)   Singh, N. and Cramer, C.S. 2019. Improved tolerance for onion thrips and Iris yellow spot in onion plant introductions after two selection cycles. Horticulturae 5:18. doi 10.3390/horticulturae5010018. Mandal, S. and Cramer, C.S. 2019. Progress made for Fusarium basal rot resistance, p. 17. In: Proc. 2019 International Allium Research Symposium. M. Havey (Ed.) Madison, WI. (Abstract)   Mandal, S. and Cramer, C.S. 2019. Selection for Fusarium basal rot resistance using an artificial inoculation mature bulb method, p. 29. In: Proc. 2019 International Allium Research Symposium. M. Havey (Ed.) Madison, WI. (Abstract)   Kvitko, B., Stice, S. and Dutta, B. 2019. The best offense is a good defense: plasmid-borne allicin tolerance genes make major contributions to Pantoea spp. virulence on onion. International Allium Research Conference, Madion WI, 24 July, 2019.   <ol start="2"> <li> Abstracts and Papers at National Professional Meetings </li> </ol>   Agarwal, G., Kvitko, B., Stice, S. and Dutta, B. 2019. Whole genome sequencing of Pantoea ananatis strains to identify variants linked to onion virulence. International Allium Research Conference, 24 July, 2019, Madion WI.   Ilyas, U., Raizada, M., du Toit, L.J. and McDonald, M.R. 2019. Mycorrhizal fungi in the roots of onion and carrot in relation to mycorrhizal fungal inoculant and soil phosphorus. Plant Canada 2019, 7-10 July, 2019, University of Guelph, Ontario, Canada. (Abstract 192)   Kvitko, B., Stice, S. and Dutta, B. 2019. A chemical arms race in onions: plasmid-borne allicin tolerance genes make major contributions to Pantoea spp. virulence on onion. American Phytopathological Society-Plant Health 2019. Cleveland, OH, 6 August, 2019.   Mandal, S. and Cramer, C.S. 2019. Identification of steroidal saponins in onion basal plate tissue involved in plant defense against Fusarium oxysporum f. sp. cepae, In: Proc. 2019 National Allium Research Conference. M. Havey (Ed.) Madison, WI. (Abstract)   Mandal, S. and Cramer, C.S. 2019. Progress made for Fusarium basal rot resistance. In: Proc. 2019 National Allium Research Conference. M. Havey (Ed.) Madison, WI. (Abstract)   Mandal, S. and Cramer, C.S. 2019. Selection for Fusarium basal rot resistance using an artificial inoculation mature bulb method. In: Proc. 2019 National Allium Research Conference.  M. Havey (Ed.) Madison, WI. (Abstract)   Scott, J.C., Jeliazkova, E., Cheng, Q., Qian, Y., Qian, M. and Dung, J.K.S. 2019. Evaluation of alternatives to soil fumigants and diallyl disulfide for the management of white rot. National Allium Research Conference, Madison, WI.   Stice, S., Dutta, B. and Kvitko, B.H. 2019. Gene cluster in onion bulb rotting bacteria contributes to virulence by conferring tolerance to reactive sulfur species. Annual Meeting of Southern Division American Phytopathological Society in Gainesville, FL (7-9 February, 2019)           <ol start="3"> <li> Reports at Grower Meetings and Field Days</li> </ol>   Cramer, C.S. 2019. Evaluation of onion germplasm to mitigate the effects of Iris yellow spot virus. Multistate Research Project W3008: Integrated Onion Pest and Disease Management, Annual Meeting, Madison, WI, 24 July, 2019.   Cramer, C.S. 2018. Progress for breeding for Fusarium basal rot resistance in onions. Multistate Research Project W3008: Integrated Onion Pest and Disease Management, Annual Meeting, and 2018 Pacific Northwest Vegetable Growers Association Annual Meeting, Kennewick, WA, 13 November, 2018.   Dung, J. 2019. White Rot Research: USDA-NIFA Grant Update. Invited speaker. California Garlic and Onion Research Advisory Board Allium Research Symposium. 11 February, 2019. Tulare, CA (~60 attendees)   du Toit, L.J. 2019. Specialty vegetable seed production. Invited presentation, Western Region IR-4 SLR/CLC Meeting, 9-10 April, 2019, Mount Vernon, WA. (25 people)   du Toit, L.J. 2019. Regionally appropriate fungicide programs. Invited presentation, Wilbur Ellis Grower Meeting, 21 Febuary, 2019, La Conner, WA. (50 people)   du Toit, L.J. 2019. Onion disease management. Invited presentation and discussion with Agri Northwest growers, 7 February 2019, Pasco, WA. (50 people)   du Toit, L.J. 2019. Late-season disease management in onion production. Invited presentation at Clearwater Supply Winter Growers’ Meeting, 6 February, 2019, Ontario, OR. (75 people)   du Toit, L.J. 2019. Regionally appropriate fungicide programs. Invited presentation, Columbia Basin Crop Consultants Association Short Course, 4-5 February, 2019, Moses Lake, WA. (150 people)   du Toit, L.J. 2019. Management of Rhizoctonia in onion seedbeds and direct-drilled crops, and postharvest management of black mold in onion crops. Invited presentation, KORKOM onion growers, 23 January, 2019, Ceres, South Africa. (15 people)   du Toit, L.J. 2019. Appropriate use of fungicides. Invited presentation, Columbia Basin Vegetable Seed Association Annual Meeting, 15 February, 2019, Moses Lake, WA. (75 people)   du Toit, L.J. 2019. Appropriate use of fungicides. Invited presentation, Annual Basin Producers’ 2019 Pesticide Recertification Day, 14 February, 2019, Moses Lake, WA. (275 people)   du Toit, L.J. 2018. Management of Fusarium basal rot of onion. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 November, 2018, Kennewick, WA. https://pnva.org/2018-pnva-conference-presentations/ (200 people)   du Toit, L.J. Regionally appropriate fungicide programs for common onion pathogens in the Columbia Basin. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention and Trade Show, 14-15 November, 2018, Kennewick, WA. https://pnva.org/2018-pnva-conference-presentations/ (200 people)   Ingham, R. and Waters, T.D. 2018. Nematode management in onions. Pacific Northwest Vegetable Association Annual Convention and Trade Show, Kennewick, WA. (200 people).   Malla, S. 2019. Vegetable & Wheat Spring Field Day. Texas A&M AgriLife Research & Extension Center, Uvalde, TX. May, 2019.   Mandal, S. and Cramer, C.S. 2019. Progress made for Fusarium basal rot resistance. 2019 National Onion Association Summer Convention, Madison, WI. July 24-27, 2019.   Mandal, S. and Cramer, C.S. 2019. Selection for Fusarium basal rot resistance using an artificial inoculation mature bulb method. 2019 National Onion Association Summer Convention, Madison, WI. July 24-27, 2019.   Mandal, S. and Cramer, C.S. 2019. Identification of steroidal saponins in onion basal plate tissue involved in plant defense against Fusarium oxysporum f. sp. cepae. 2019 National Onion Association Summer Convention, Madison, WI. July 24-27, 2019.   Reitz, S. 2018. Thrips and IYSV Management in the Treasure Valley. Pacific Northwest Vegetable Association Annual Meeting.   Reitz, S. 2019. Thrips/IYSV Management. Idaho-Malheur County Onion Growers Associations Annual Meeting Soilborne disease management in carrot, onion, brassica, and beetroot production in sandy soils of the Sandveld region of South Africa. Invited discussion/workshop with agronomists and production managers for Laastedrif Farm, 23 January, 2019, Ceres, South Africa. (12 people)   Waters, T.D. 2018. Thrips Management in Dry Bulb Onions. SW Ag Summit, Yuma, AZ. (100 people).   Waters, T.D. 2018. Thrips control in dry bulb onions. Pacific Northwest Insect Management Conference, Portland, OR. (60 people).   Waters, T.D. 2018. Insect control in potato and onion. Corteva Regional Customer Meeting, Las Vegas, NV. (60 people).   Waters, T.D. 2018. Thrips and seedcorn maggot control in onions. 2018 Walla Walla Onion Growers’ Meeting organized by CHS Primeland. Walla Walla, WA. (20 people).   Waters, T.D. 2018. Potato and onion insect IPM update. Agri Northwest Agronomy Meeting. Kennewick WA. (50 people).   <ol start="4"> <li>Newsletter Articles</li> </ol>   WSU Onion Alerts (https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792): Time-sensitive topics covered in seven articles between 30 May  and 21 August  of 2019 included downy mildew, fungicides, thrips, nematodes, iris yellow spot, irrigation, and powdery mildew.   Gugino, B.K. 2019. Black mold on onion and other common diseases on onion. Pennsylvania Vegetable Disease Update. 3 July, 2019. <a href="https://extension.psu.edu/vegetable-disease-updates-for-july-3-2019">https://extension.psu.edu/vegetable-disease-updates-for-july-3-2019</a>.   Putman, A.I. 2019. Downy mildew of vegetables in Imperial County. Imperial County Agricultural Briefs 22(3): 39-42. Putman, A.I. 2019. Transition period from downy mildew to powdery mildew. Imperial County Agricultural Briefs 22(4): 76-78.   Winkler, L., du Toit, L. and Waters, T. 2019. Mycorrhizal inoculants: Yea or nay? The effects of mycorrhizal inoculants on onion crops in the Columbia Basin. Onion World February, 2019:10-14. <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__issuu.com_columbiamediagroup_docs_feb-5F2019-5Fonion-5Fworld-5Fweb-3Fe-3D34405975_67413329&d=DwMGaQ&c=C3yme8gMkxg_ihJNXS06ZyWk4EJm8LdrrvxQb-Je7sw&r=FOfNcQR_IrAnsHDEWvKAuQ&m=PsHHIHBotsutSMAc4BrXEn2N8gznNQRY4na15p6bvT8&s=uAaY-dgQkltxJC61HzXq6gdG9jdbEMupY0AejqstPnc&e=">https://issuu.com/columbiamediagroup/docs/feb_2019_onion_world_web?e=34405975/67413329</a>   <ol start="5"> <li> Annual Reports</li> </ol> Cramer, C.S. Evaluation of onion germplasm to mitigate the effects of Iris yellow spot virus. Sustainable Agriculture Field Day. Las Cruces, NM. June 26, 2019. Dung, J. and Scott, J. 2018. Microplot evaluation of sclerotia germination stimulants for white rot control in garlic. Central Oregon Agricultural Research and Extension Center 2018 Annual Report: 26-28.   Reitz, S.R. 2019. Monitoring Onion Pests Across the Treasure Valley - 2018. pp. 111-115. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2018, Department of Crop and Soil Science Ext/CrS 161.   Reitz, S.R., Trenkel, I. Wieland, K., Shock, C.C., Feibert, E.B.G. and Rivera, A. 2019. Thrips and Iris Yellow Spot Virus Management in the Treasure Valley. pp. 116-134. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2018, Department of Crop and Soil Science Ext/CrS 161.   Reitz, S.R., Trenkel, I. Wieland, K., Shock, C.C., Feibert, E.B.G. and Rivera, A. 2019. Effects of Drip Applications of Fontelis Fungicide for Pink Root Management. pp. 111-115. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2018, Department of Crop and Soil Science Ext/CrS 161.   <ol start="6"> <li> Internet Resources</li> </ol> Pacific Northwest Vegetable Extension Group (PNW VEG) website (<a href="http://mtvernon.wsu.edu/path_team/vegpath_team.htm">http://mtvernon.wsu.edu/path_team/vegpath_team.htm</a>), a tri-state Extension team with resources on diverse vegetables grown in the PNW USA. Sections on onions include the Photo Gallery (<a href="http://mtvernon.wsu.edu/path_team/onion.htm">http://mtvernon.wsu.edu/path_team/onion.htm</a>) and IPM Resources (<a href="http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion">http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion</a>). Wyenandt, A., Koehler, A., Everts, Rideout, K.S. and Gugino, B. 2019. Fungicide Resistance Management Guidelines for Vegetable Crops Grown in the mid-Atlantic Region – 2019. <a href="https://extension.psu.edu/2019-fungicide-resistance-management-guidelines-for-vegetable-crops">https://extension.psu.edu/2019-fungicide-resistance-management-guidelines-for-vegetable-crops</a>. (contains a table for onion) Reitz, S.R. and Dung, J. 2019. <a href="http://Cropinfo.net">Cropinfo.net</a> <a href="https://agsci.oregonstate.edu/mes/malheur-experiment-station">https://agsci.oregonstate.edu/mes/malheur-experiment-station</a>

Impact Statements

Washington (du Toit, Waters, Pappu): Collaborative efforts and networking of W-3008 members led to successful submission and funding of a $4.0 million + $4.2 million matching funding, 4-year USDA NIFA SCRI grant to help onion stakeholders address the negative impacts of bacterial diseases on onion production in the USA. The project was ranked highly by the review panel, particularly the well-established national network of collaboration among 24 onion researchers and extension specialists with growers and other onion stakeholders across the USA. This productive collaboration has resulted, in part, from the many years of synergistic interactions through the W-1008, W-2008, and now the W-3008.

Date of Annual Report: 04/01/2021

Report Information

Annual Meeting Dates: 02/03/2021 - 02/03/2021
Period the Report Covers: 07/24/2019 - 02/03/2021

Participants

Participants Attachment:

W3008 Final Report Draft (2020-21) FSH edit (002).pdf

Brief Summary of Minutes

The meeting began promptly at 11:00 AM Eastern.

Welcome and Introductions: Bhabesh Dutta (Chair) led each participant to introduce themselves, describe their professional association and areas of interest.

Tracy Dougher - During the introductions, Tracy gave some feedback on the mid-term report that more highlight needs to be given to “your linkages and how you work as a multi-state group,” but that the reports are excellent. Tracy also mentioned the expiration of W-3008 and the submission deadline for the next project is no later than January 15^th of 2022, along with the comment that the annual report is due 60 days after this meeting (secretary note - April 3, 2021).

Bhabesh Dutta – Bhabesh reiterated that Peter Rogers will be responsible to collect state reports, David Burrell will be responsible for submitting the minutes of the meeting. After review by the officers Peter will then send both to Tracy. Bhabesh commented that each state has 20 minutes allocated for their presentation.

State Report Section - details in uploaded file

Election New Officers

2:50 PM

Bhabesh reported that Peter Rogers is in line to be the Chair, David Burrell is in line to be the Vice-Chair, and a Secretary was required, preferably from Academia. Much discussion occurred. Bhabesh reported that Sarah Pethybridge nominated Frank Hay from Cornell University New York, Mark seconded the nomination. Frank Hay was accepted as Secretary. Passed without opposition.

The officers for 2021-2022 are as follows:

Peter Rogers, chair - peter.rogers@vegetableseeds.basf.com

David Burrell, vice-chair – davidb@onionlabs.com

Frank Hay, secretary – fsh32@@cornell.edu

Bhabesh Dutta, past-chair – bhabesh@uga.edu

Annual Meeting Discussion

Discussion occurred regarding coordination of the W3008 meeting with the NOA Annual meeting, the NARC meeting and or the NW Regional Veg Grower meeting in Pasco WA. Many alternatives were discussed. Kerrick Bauman proposed an easy to fly into hub for the meeting. Denver and Salt Lake locations were suggested. Plan on Denver first then accept Salt Lake as a second location with exact dates to be determined.

W-4008 Discussion Proposal

W-3008 will end September 2022, so a W-4008 will be needed to be submitted no later than January 15, 2022. Brian Nault will lead the writing with contributions from various collaborators. Comments were shared that breeding support in both the public and private sector and cultivar evaluation might have been an underserved aspect of the W-3008 project.

The floor was opened by Bhabesh for comments.

Stuart Reitz commented that some new participants were involved, and that it might be beneficial to share the 2018 project documents with the new participants.

Kerrick Bauman commented that the group is very valuable and needs help with outreach to connect with the stakeholders. The outreach needs to be user friendly and the stakeholders have a huge resource that is under- utilized.

Discussion occurred regarding re-allocating any unused travel funds to help support the allium net development.

Discussion occurred that there is a huge need with packers / shippers to understand how the packing equipment is safe and sterilized. This is a huge area of interest regarding food safety. Discussion occurred if this should be a part of the W4008 project. Comments were shared for the group to be aware of this aspect of the food safety issue.

Comments were shared regarding interest in use of precision agriculture in Ag in Georgia. Food safety, precision ag, and disease management and breeding can become more focused. Comments were shared regarding interest in the relationship between plant nutrition and disease expression.

Bhabesh concluded the meeting with the comments that Peter Rogers will be responsible for compiling the state reports. David Burrell will be responsible for the writing the minutes of the meeting. Both of these will be submitted to the committee officers for review before they are submitted to Tracy.

Meeting closed

3:10 PM

Accomplishments

Objective 1. Evaluate onion germplasm for resistance to pathogens and insects. New Mexico (Cramer): Twenty-eight entries of original, intermediate, and advanced FBR-selected onion populations (4 reps) were sown in fields at the Fabian Garcia Science Center (FGSC) in October 2019. From late May to late June of 2020, bulbs were harvested once plants had reached maturity. After harvest, the basal plate of all bulbs was cut transversely and a 1 cm diameter plug of FOC isolate CSC 515 (spore concentration of 3 x 104 sporesml-1) was applied to the cut surface. Following 21 d of incubation, the basal plate was rated (1-9). Of the FBR-selected populations, recent selections of ‘NuMex Chaco’, ‘NuMex Crispy’, and ‘NuMex Mesa’ exhibited less disease than their original cultivar generation, the susceptible check and the resistant check. Results indicate that breeding for FBR resistance has been successful in producing more resistant germplasm. New York (Nault, Hoepting, Pethybridge, Hay): Fourteen onion varieties (95 to 120 days maturity) were evaluated for differences in susceptibility to bacterial bulb rot. An identical trial was set up that was artificially inoculated leaves at 10% lodging with a mixture of Pantoea agglomerans and P. ananatis 109 colony forming units (cfu)/ml. Both trials were set up as split-plot designs with copper bactericide (Badge 2 pt/A) as the main factor, which was applied to one-third of each plot length weekly beginning at first leaf senescence until 50% lodging. The varieties were divided into three maturity cohorts to ensure that copper application and artificial inoculation were consistent within crop stage. Varieties that tended to have lower incidence of bulb rot included Stanley, Red Mountain, SVNY1141 and Saddleback. Similarly, varieties that tended to have more rot included Red Wing, Ridgeline, SVNY1298 and Montclair. Catskill, Pocona and Braddock had mid-range bulb rot. Hamilton demonstrated good tolerance to bulb rot. There was no relationship between maturity and bulb rot Onion thrips management programs consisting of several different tactics were evaluated over two years. Treatments included a) two onion plant cultivars with semi-glossy leaves (‘Rossa di Milano’ and B5336A x B5351C) and one with waxy leaves (‘Bradley’), b) silver reflective and white plastic mulches, and c) with or without an application of a bioinsecticides (spinosad + neem oil). Thrips densities were counted weekly and bulbs weighed at harvest. The cultivar ‘Rossa di Milano’ had fewer thrips compared with ‘Bradley’ and B5336A x B5351C, but also had the lowest yield. Reflective mulch had lower thrips densities than white mulch, but had no effect on yield. Bioinsecticides were most effective at reducing thrips densities and increasing yield. No other tactics provided significant additional benefits to thrips management. Idaho (Schroeder, Thornton and Woodhall): Twenty cultivars of Spanish yellow storage onions were inoculated with 1 x 105 spores of Fusarium proliferatum per bulb in September, right after harvest and stored under commercial conditions at the Malheur Experiment Station. Bulbs were evaluated for percent surface area exhibiting rot 6 months after inoculation.  Second year of trial determined that Oloroso, Vaquero, Tucannnon, Sedona, Pandero were the most susceptible exhibiting rot between 20-25% of the surface area.  The most resistant cultivars included Scout, 16000, Avalon and Grand Perfection with less than 15% of the surface area exhibiting rot. Oregon (Reitz, Dung and Qian): Thrips and IYSV are the most important pests of onions grown in the Treasure Valley of eastern Oregon and in the southwest Idaho. As part of ongoing Onion Variety trials conducted at the Malheur Experiment Station, cultivars were rated during the season for thrips damage and severity of iris yellow spot as well as yield and quality. Bulbs from the 2020 trial are in storage awaiting grading in January.  Utah (Drost, Nischiwitz): Facilitated acquisition of and distribution of onion varieties for evaluation by grower cooperator Bret Fowers (Bear River City, Utah). Growers planted seed in early April 2020 and collected production data. Crop evaluated periodically during year and no differences in pest or disease pressure were noted. Assessed establishment and early growth of density trials planted (planted March 19-21, 2020) on Bennett and Norman Farms in Weber/Box Eder Counties. Evaluated impacts on growth, pest pressure and disease incidence. Grower management in trials was excellent and few pest or disease problems were noted. Washington (du Toit, Waters, Pappu): The Washington State University Onion Cultivar Trial was planted in April 2020 near Pasco, WA, with three replicate plots of each of 51 cultivars submitted by various onion seed companies. The plots were evaluated regularly for diseases and pests. Bulbs were harvested from the plots in September to assess yield, and 50 bulbs/plot were placed in storage to evaluate for storage quality and storage rots in February 2021.   Objective 2. Investigate the biology, ecology and management of onion Thrips and other pests. New York (Nault, Hoepting, Pethybridge, Hay): Combinations of fertilizer and insecticide use were evaluated for onion thrips management in commercial onion fields in 2019-20. Main plot treatments included no fertilizer, the grower’s full rate of fertilizer and the grower’s half rate of fertilizer. Sub-plots included either an action-threshold based insecticide program or a weekly insecticide application program. Thrips populations and marketable bulb yield were not affected by fertilizer treatment. The action-threshold based insecticide program was highly successful and controlled thrips with an average of two fewer applications than spraying weekly. Mechanisms of spinosad seed treatment for protecting onion seedlings from onion maggot were investigated. Results showed that spinosad was more than twice as lethal to one-week old larvae than two-week old larvae when it was ingested. In contrast, spinosad was equally toxic to both larval ages via contact exposure. In choice assays, larvae preferred feeding on untreated plants seventy-five percent of the time compared with spinosad-treated ones; however, without a choice, larvae fed and survived equally well on untreated and treated plants. These results provide valuable insight into the mechanisms for how spinosad protects onion seedlings against onion maggot. An insecticide trial was conducted to find a highly effective insecticide treatment that could be used in rotation with Radiant under high thrips pressure. A trial was initiated when thrips were 20 per leaf. After the first spray all treatments reduced thrips to the same extent as Radiant 10 fl oz/A (~69% control), except Exirel 20 fl oz + Lannate LV 3 pt/A + Warrior 1.9 fl oz/A, which had significantly fewer thrips than Radiant. After the second spray, Exirel + Lannate + Warrior, Exirel 20 fl oz/A + Lannate LV 3 pt, Minecto Pro 10 fl oz + Warrior and Exirel 20 fl oz resulted in 94 – 96% control of thrips with no difference among them and significantly fewer onion thrips than the Radiant 10 fl oz/A and Minecto Pro 10 fl oz/A.  Idaho (Schroeder, Thornton and Woodhall):  Analysis was completed for Fusarium proliferatum storage assays.  Storage assays evaluated the impact of Fusarium proliferatum on Vaquero under different curing temperatures and durations.  The bulbs were inoculated with 1 x 105 spores per bulb in September right after harvest cured at 25, 30, 35, 40°C for 2 days or 2 weeks and then stored at 5°C.  Bulbs were evaluated for percent surface area exhibiting rot 6 at 4 months and 6 months after storage.  With the 2 day curing assays it is apparent that the amount of bulb rot is reduced from ~40% for bulbs cured at 25°C to~25% for bulbs cured at 40°C.  Interestingly, when bulbs are cured for 2 weeks bulbs temperature did not appear to be a factor and all the bulbs across curing temperatures exhibited ~40% of the surface area with rot.  Oregon (Reitz, Dung and Qian): Ongoing insecticide efficacy trials demonstrated effectiveness of new insecticide use programs to better manage thrips and IYSV in the Treasure Valley. As part of a USDA-SCRI grant we completed a second year of field trials to assess how nitrogen fertilization combined with insecticide management programs based on sampling thresholds or scheduled applications affect thrips and iris yellow spot. In addition to these IPM field trials, we are conducting laboratory trials to assess susceptibility of local thrips populations to commonly used insecticides. In August, we established colonies of five thrips populations from commercial onion fields in the Treasure Valley for use in these trials.  A regional pest-monitoring program provided information to growers on seasonal pest trends, including changing patterns in thrips and IYSV incidence. Texas (Malla): Thrips monitoring using yellow sticky traps showed that the insect population slowly increased from the second week of February 2020 (average 82 thrips/trap; Trece Inc., OK) in the organic nursery. The insect population reached peak on the third week of March 2020 (avg 1,059 thrips/trap). Washington (du Toit, Waters, Pappu): Several insecticide efficacy trials were conducted to evaluate control options for onion thrips (Thrips tabaci) management. One trial featured new unregistered insecticides, one of which was nearly as efficacious as Radiant (spinetoram), which is currently the most effective insecticide available for use by producers. Another trial looked at products that are currently registered for use on onions, but that are not used to manage onion thrips. None of those insecticides provided consistent efficacy that compares to products that are currently already in use. In collaboration with Dr. Doug Walsh, we also evaluated insecticide resistance in onion thrips found in commercial fields. We tested for resistance to Radiant (spinetoram), Movento (spirotetremat), and Torac (tolfenpyrad). Results are still being evaluated. Alternative insecticides were also tested for control of seed corn maggot (Delia platura). Pest pressure was lower than anticipated and as such, we did not detect any differences among the insecticides screened. The genetic diversity of onion thrips (Thrips tabaci) in various onion-growing regions of the US is being determined. The 658 bp fragment of the COI-5ʹ was used to carry out barcoding. Haplotypes were generated using sequence polymorphism software (DnaSP 5.10). A total of 15 T. tabaci samples from eight locations (four states) were analyzed. Two T. tabaci haplotypes with haplotype diversity of 0.740 ± 0.030 and 14 polymorphic sites (SNPs) were found. Haplotype 1 was the most common haplotype.   Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens. California (Putnam): Field trials were initiated in October 2019 in Holtville, Brawley, and Sacramento Valley CA, to evaluate the utility of weather-based models to schedule fungicide applications to manage downy mildew of onions for processing (Holtville and Brawley) or seed (Sacramento Valley). A weather station was established within study area to measure standard parameters at a height of 2 m, including temperature, relative humidity, and leaf wetness within the plant canopy. The standard calendar treatment was initiated in late February at Holtville and Brawley and the second application was made at Brawley on March 13, 2020. Active downy mildew was observed at both Holtville and Brawley in mid-April, but disease was not observed at the Sacramento Valley location. To summarize the two trials in 2019-2020, at Brawley, the same control was achieved by either two applications (standard calendar) or one application (weather-based model) in a low disease incidence situation.  At Holtville, the model-based treatments could not be evaluated.  However, a single application of Ridomil Gold Bravo on February 25, approximately 14 days prior to a major weather event, provided complete numeric control of moderate to severe downy mildew. Georgia (Dutta, Kvitko): In a study, foliar treatments of acibenzolar-S-methyl (Actigard 50WG), cupric hydroxide (Kocide 3000), and Actigard + Kocide were evaluated for their effectiveness in the presence and absence of thrips infestation at two critical onion-growth stages; bulb initiation and bulb swelling.  Onion growth stage had no impact on effectiveness of either Kocide or Actigard.  In the absence of thrips, Kocide application resulted in reduced center rot incidence compared with Actigard, regardless of the growth stage.  However, when thrips were present, the efficacy of both Kocide and Actigard was reduced with bulb rot incidence not significantly different from the non-treated control. In independent greenhouse studies in the presence or absence of thrips, it was observed that use of protective chemicals (Kocide  or Actigard or combinations) at different rates also affected the incidence of bulb rot. These results suggest that thrips infestation can reduce the efficacy of protective chemical treatments against P. ananatis. Therefore, an effective center rot management strategy should likely include thrips management in addition to bactericides at susceptible growth stages of onion. In order to assess the distribution of HiVir and alt gene clusters, two PCR primer sets were designed. Two hundred fifty-two strains of Pantoea spp. were phenotyped using the red onion scale necrosis (RSN) assay and were assayed using PCR for the presence of these virulence genes. A diverse panel of strains from three distinct culture collections comprised of 24 Pantoea species, 41 isolation sources, and 23 countries, collected from 1946-2019, were tested. There is a significant association between the alt PCR assay and Pantoea strains recovered from symptomatic onion (P<0.001). There is also a significant association of a positive HiVir PCR and RSN assay among P. ananatis strains but not among Pantoea spp., congeners. This may indicate a divergent HiVir cluster or different pathogenicity and virulence mechanisms. Lastly, a combination of assays that include PCR of virulence genes [HiVir and alt] and an RSN assay can potentially aid in identification of onion-bulb-rotting pathogenic P. ananatis strains. New York (Nault, Hoepting, Pethybridge, Hay): Forty treatments including an untreated control were evaluated for Stemphylium leaf blight efficacy across two on-farm small-plot field trials in Elba, NY. Poor or no control of SLB was observed with 1) FRAC 7 fungicides a.i.s belonging to four sub-classes including fluopyram (Luna Tranquility/Experience), fluxapyroxad (Merivon), pydiflumetofen (Miravis Prime) and isofetamid (Kenja, note: not labeled on onion); 2) FRAC 3 fungicides with two active ingredients including difenoconazole (Inspire Super, Quadris Top) and propiconazole (Tilt); 3) FRAC 2 a.i. iprodione (Rovral); 4) FRAC 9 a.i. pyrimethanil (Scala); 5) FRAC M5 a.i. chlorothalonil (Bravo); 6) FRAC 22 a.i. zoxamide (Gavel); FRAC M1 a.i. copper hydroxide (Badge); 7) FRAC 29 a.i. fluazinam (Omega); and 8) FRAC 21 a.i. fenpicoxamid. Viathon 3 pt + Tilt 9 fl oz (FRAC 3 + 3) had significantly healthier plants than all other treatments in the trial.  In general, acceptable control of SLB only occurred with FRAC 3 + 3 combinations, Viathon alone (a.i. tebuconazole), Luna Tranquility 16 fl oz + Rovral 1 pt and high rates of Scala 18 fl oz + Rovral 1.5 pt.  The genetic basis of reduced effectiveness of FRAC 7 fungicides against Stemphylium leaf blight in NY was examined. Resistance of Stemphylium vesicarium to FRAC 7 fungicides was associated with at least eight single nucleotide polymorphisms in the succinate dehydrogenase genes, SdhB, SdhC and SdhD. Some 95-100% of S. vesicarium isolates considered insensitive (EC50>10µg/ml) to fluxapyroxad, fluopyram and penthiopyrad contained at least one of these mutations, with the most common mutations being C135R, H134R and G79R in the SdhC. For boscalid, 57% of isolates with EC50>10µg/ml had at least one of these mutations, with a predominance of C135R and H134R mutations in the SdhC. Many of these mutations appear to confer cross resistance amongst fluxapyroxad, fluoyram, penthiopyrad and boscalid, limiting the effectiveness of the FRAC 7 group for the control of Stemphylium leaf blight. Idaho (Thornton and Woodhall):  A LAMP assay was designed for S. cepivora which can detect the pathogen within 6 minutes in highly infested material. TaqMan assays for Stemphylium vesicarium and Pantoea agglomerans have been designed and have been used to detect both pathogens in rain splash traps. Stemphylium vesicarium was detected in Burkard spore traps. Field trials were completed to compare the efficacy of Fontelis applied via drip irrigation to commercial products (Fontelis + Proline, Elatus, Luna Experience, Velum Prime +Serenade) that contain mixtures of two different fungicides. The incidence of bulbs showing any symptoms of pink root ranged from 95 to 100% on July 7 and from 97 to 100% on July 29, indicating relatively high disease pressure.  Velum Prime and Elatus were the only treatments that had significantly lower incidence of disease on July 7 compared to the non-treated check.  Oregon (Reitz, Dung and Shock): We completed two field trials to assess cultural management techniques and bactericide efficacy on bacterial rot of onions. In the cultural management trial, we examined the effects of irrigation amount and timing, and nitrogen fertilization on bacterial rot. An additional factor was bacterial inoculation. One-half of the trial was inoculated twice and one-half was not inoculated. Efforts in another USDA-SCRI grant focused on integrated management of white rot. Diallyl disulfide (DADS), isopropyl disulfide, dipropyl disulfide (DPDS), and dimethylsulfoxide were evaluated alone at 0.1, 1, and 2 gal/A rates and in all two-, three-, and four-way combinations (1 gal/A each) in growth chamber trials. All individual compounds significantly reduced sclerotia counts in soil, with the lowest sclerotia counts recorded in DADS (1 and 2 Gal/A) or DPDS (2 Gal/A) treated soils. Additive or synergistic effects were not observed when sulfur compounds were combined. Novel fungicides were screened for white rot control in a garlic field trial. Pyraziflumid, pydiflumetofen, benzovindiflupyr were evaluated as in-furrow applications and compared to tebuconazole, penthiopyrad, and a non-treated control. All of the fungicides increased stand counts and plant heights and reduced disease severity in April. By June, plots treated with tebuconazole, pyraziflumid, and pydiflumetofen exhibited reduced disease severity. Tebuconazole and pyraziflumid significantly increased marketable yields compared to the non-treated control. Pennsylvania (B.K. Gugino): During the 2020 production season, 10 whole onion plants samples with characteristic center rot bacterial disease symptoms were collected from each of five fields in Centre, Clinton, and Lancaster Co., PA at two time points during the season (8 to 9 leaf stage and at harvest). From each plant, isolations were made on OEM and NA media and up to six unique bacterial colonies were selected from each media. A total of approximately 600 bacterial isolates were collected from PA fields and stored at -80C. Samples were also collected from NY onion fields and processed in a similar manner under an APHIS 526 permit for a total of 1238 isolates. An additional 136 bacterial isolates were obtained from NY post-harvest samples in Dec 2020/Jan 2021. DNA from approximately 500 isolates have been sequenced thus far and 160 isolates have undergone red scale pathogenicity testing with 93% being characterized as pathogenic. Colorado (Uchanski, Machado, Bartolo, Davey): Mark Uchanski and graduate student (Antoinette Machado) and new research associate (Jane Davey) conducted Stop the Rot field surveys in 2020 as well as conducted bactericide trials at ARDEC South with two cultivars of onions.  Utah (Drost, Nischiwitz): Onion bacteria disease management trial planted in March at the USU Kaysville Research Station in Kaysville, Utah. Trial inoculated with Pantoea allii. After bulbs initiated bulbs were treated weekly with a range of possible bactericides. Infection incidence was recorded for the inoculated, non-inoculated, and percent incidence calculated. In inoculated treatments, incidence ranged from 14-28% while in the non-inoculated plots, incidence of bacterial infection was 12-31%. Bulbs were harvested, cured, and stored to early December. Evaluations of bulbs for bacterial diseases is ongoing. Washington (du Toit, Waters, Pappu): In October 2019, metam sodium soil fumigation trials were set up in the Columbia Basin to assess the efficacy of 4 methods of application of Sectagon (chemigated at 40 gpa, shanked at 10” depth at 40 gpa, shanked at 4 and 10” depths at a total 40 gpa, and chemigated at 20 gpa + shanked at 10” depth at 20 gpa) compared to non-fumigated control plots. One trial was in a grower’s field near Othello that had a high population of stubby root nematode, and the other trial was near Pasco that had high populations of the pink root pathogen. In the Pasco trial, most metam sodium was at the 4” depth in chemigated plots, whereas shank applications distributed metam sodium more evenly from 6 to 10” deep. More metam sodium was detected in plots with shank applications compared to plots with chemigation. At the Othello trial, soil moisture was ~80% saturation during fumigation, (recommended soil moisture) for effective fumigation than the 50% at the Pasco trial during fumigation. Metam sodium levels in plots with chemigated + shanked applications were at least 4x greater in the Othello trial than the Pasco trial. This showed the importance of adequate soil moisture during fumigation with metam sodium. The results suggested very limited or no efficacy of the chemigated and shanked applications of Sectagon 42 for control of weeds, pink root, Fusarium basal rot, and nematodes. Research was initiated in fall 2019 on the project ‘Stop the rot: Combating onion bacterial diseases with pathogenomic tools and enhanced management strategies’. In 2020, 5 onion bulb crops were surveyed twice for symptoms of bacterial diseases. Isolations yielded >300 bacterial strains being identified using DNA sequencing, and tested for pathogenicity on onions. Strains will be part of the National Onion Bacterial Strain Collection. Nine onion field trials were set up in WA in 2020: 1) bactericide trial, 2) cultivar screening trial, 3) postharvest bulb treatments, 4) timing of topping onion bulbs, 5) undercutting onion bulbs, 6) rolling onion tops before harvest, 7) nitrogen fertilizer program, 8) frequency of irrigation, and 9) timing of terminating irrigation. Bulbs from the trials are in storage to be evaluated for bacterial rots.   Objective 4.  Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management. New York (Nault, Hoepting, Pethybridge, Hay): Despite safety restrictions for COVID-19 for a majority of the past year, some of our results were presented at meetings throughout New York and beyond. The Stop the Rot project is a multi-state, multi-disciplinary, multi-year and multi-million dollar USDA-NIFA project whose six co-PIs are members of W3008. 2020 marked the first year of research trials across the nation for the Stop the Rot project. Interaction with onion industry stakeholders include: 1) Stop the Rot project has a 15-member stakeholder advisory panel that includes onion growers and allied industry members from all major onion growing regions; 2) An article featuring an introduction to this ambitious project was published in Onion World (see publication section; and 3) Alliumnet website is going to be re-vamped to become the home for national onion collaboration content including i) National USDA-NIFA collaborative onion projects; ii) National Allium Research Conference (NARC), and iii) W4008. Georgia (Dutta, Kvitko): Four trainings for county extension agents and professionals in Georgia, 15 Georgia producer trainings, and 4 national or regional invited extension presentations were conducted to disseminate updated information on onion disease management. These meetings have covered onion disease management through transfer of information and technology in Georgia. Pennsylvania (Gugino) Aided in the diagnosis of onion and other allium samples submitted to the Penn State Plant Disease Clinic, as needed. Research results were disseminated through one-on-one interactions with growers as well as winter meetings with vegetable growers and training update for PDA inspectors. Washington (du Toit, Waters, Pappu): Newsletter articles were written and distributed to >600 subscribers, mostly in the Pacific Northwest USA, via the WSU Onion Alerts. The ‘Stop the Rot’ onion SCRI team met for 2 days at the Univ. of GA in February 2020 for orientation to the whole project and to plan the 1st of the 3 field seasons of the project. The meeting included a hands-on lab session to review basic methods to be used for the 12-state survey of onion bulb crops for bacterial diseases. Workshop was attended by 25 team members, including faculty, technical staff, post-doctorates, graduate students, and some of the Stakeholder Advisory Panel members.  California (Putnam): The partnership with a seed company will continue in the upcoming season to evaluate the model-based approach for downy mildew in seed production in CA. Oregon (Reitz, Dung and Shock): Regional pest monitoring results were sent weekly to growers and allied industry members, as were periodic newsletters. Research results and updates were communicated to the White Rot Advisory Committee via bi-monthly video conferences and at the California Garlic and Onion Research Symposium in February 2020. A webinar was presented in August 2020 as part of a brown bag seminar series hosted by the Washington State University Mt. Vernon NW Washington Research and Extension Center

Publications

Publications (October 1, 2019 to December 30, 2020) (25906 characters w/spaces) Agarwal, G., Choudhary, D., Stice, S.P., Myers, B.K., Gitaitis, R.D., Venter, S.N., Kvitko, B.H., and Dutta, B. 2020. Pan-genome-wide analysis of Pantoea ananatis identified genes linked to pathogenicity in onion. BioRxiv doi: <a href="https://doi.org/10.1101/2020.07.24.219337">https://doi.org/10.1101/2020.07.24.219337</a> Alyokhin, A., B. Nault and B. Brown. 2020. Soil conservation practices for insect pest management in highly disturbed agroecosystems – a review. Entomol. Exp. Appl. 168: 7-27. https://doi: 10.1111/eea.12863. Beck, K. D., Reyes-Corral, C., Rodriguez-Rodriguez, M., May, C., Barnett, R., Thornton, M.K., Bates, A. A., Woodhall, J. W., B. K. Schroeder. 2020 First report of Fusarium proliferatum causing necrotic leaf lesions on onion (Allium cepa) and association with increased incidence of onion bulb rot in Southern Idaho. Plant Disease: 2020. https://doi.org/10.1094/PDIS-06-20-1399-PDN. Brown L, Harrington S, Harrington M, Murdock MR, Pizolotto CA, Woodhall JW (In press). Rhizoctonia solani AG 2-2 IIIB causing root rot of onion in Idaho. Plant Disease. du Toit, L.J., Brouwer, L.R., Derie, M.L., Henrichs, B.A., Holmes, B.J., and Waters, T.D. 2020. The effect of formulation and application method of commercial arbuscular mycorrhizal fungi inoculants on onion seedlings in a growth chamber study, 2016. Plant Disease Management Reports 14:V059. du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Brouwer, L.R., Waters, T.D., and Darner, J. 2020. Effects of three arbuscular mycorrhizal fungi inoculants on pink root and yield in a commercial onion bulb crop near Othello, WA, 2017. Plant Disease Management Reports 14:V061. du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Morgan, P., Brouwer, L.R., Waters, T.D., and Darner, J. 2020. Effects of Mykos Gold Granular, an arbuscular mycorrhizal fungi inoculant, on pink root, white rot, and crop growth in spring- and fall-planted sweet onion crops near Walla Walla, WA, 2017-2018. Plant Disease Management Reports 14:V060. du Toit, L.J., Derie, M.L., Holmes, B.J., Winkler, L.R., Waters, T.D., and Darner, J. 2020. Effects of an arbuscular mycorrhizal fungal inoculant and a mycorrhizal stimulant on pink root and productivity of dehydration onion crops near Paterson, WA, 2016. Plant Disease Management Reports 14:V062. Hay, F.S., Sharma, S., Hoepting, C., Strickland, D., Luong, K., Pethybridge, S.J. 2019.  Emergence of Stemphylium leaf blight of onion in New York associated with fungicide resistance.  Plant Disease 103, 3083-3092. <a href="https://doi.org/10.1094/PDIS-03-19-0676-RE">https://doi.org/10.1094/PDIS-03-19-0676-RE</a>. Hoepting, C.A. Onion smut: Old problem, new solution – Excellent debut by new seed treatment for onion smut in New York muck onions.  Onion World, 36(6): 6-9. Hoepting, C.A. and L.J. du Toit. 2020.  Stop the Rot! National team to combat bacterial diseases of onion with fierce collaboration.  Onion World, 36(5): 8-11. Hoepting, C.A., S.K. Vande Brake and E.R. van der Heide.  2020. Variety evaluation for bacterial bulb decay in onion, 2019. Plant Disease Management Report 14:V218. https://doi-org.proxy.library.cornell.edu/10.1094/PDMR14. Hoepting, C.A., S.K. Vande Brake and E.R. van der Heide.  2020. Efficacy of fungicide treatments for control of Stemphylium leaf blight and Botrytis leaf blight in onion, Sodus, 2019. Plant Disease Management Report 14:V219. https://doi-org.proxy.library.cornell.edu/10.1094/PDMR14. Hoepting, C.A., S.K. Vande Brake and E.R. van der Heide.  2020. Efficacy of fungicide treatments for control of Stemphylium leaf blight and Botrytis leaf blight in onion, Elba, 2019. Plant Disease Management Report 14:V220. https://doi-org.proxy.library.cornell.edu/10.1094/PDMR14. Hoepting, C.A., S.K. Vande Brake and E.R. van der Heide.  2020. Effect of fungicide application timing on control of Botrytis leaf blight and Stemphylium leaf blight in onion, 2019. Plant Disease Management Report 14:V221. https://doi-org.proxy.library.cornell.edu/10.1094/PDMR14. Hoepting, C.A., S.K. Vande Brake and E.R. van der Heide.  2020. Efficacy of early timed fungicide application on control of Botrytis leaf blight and relationship with Stemphylium leaf blight in onion, 2019. Plant Disease Management Report 14:V222. https://doi-org.proxy.library.cornell.edu/10.1094/PDMR14. Iglesias, L., and B.A. Nault. 2020. Onion maggot control using insecticide transplant treatments for onion, 2018. Arthropod Management Tests 45(1): tsaa093, <a href="https://doi.org/10.1093/amt/tsaa093">https://doi.org/10.1093/Amt/tsaa093</a>. Iglesias, L., and B. A. Nault. 2020. Onion maggot control using insecticide transplant treatments for onion, 2019. Arthropod Management Tests 45(1): tsaa069, <a href="https://doi.org/10.1093/amt/tsaa069">https://doi.org/10.1093/Amt/tsaa069</a>. Iglesias, L., and B. Nault. 2020. Bioinsecticides and cultural controls for onion thrips in organic onions. . Cornell Cooperative Extension, Cornell Vegetable Program. VegEdge 16(11):  6-7. Iglesias, L. and B. Nault. 2020. Allium leafminer is no minor inconvenience: Updates from the northeastern US. Onion World  36(3): 6-9. Iglesias, L.E., R.L. Groves, B. Bradford, R.S. Harding, and B.A. Nault. 2021. Evaluating combinations of bioinsecticides and adjuvants for managing Thrips tabaci (Thysanoptera: Thripidae) in onion production systems. Crop Protection 142 doi.org/10.1016/j.cropro.2020.105527. Iglesias, L.E., M.J. Havey, and B.A. Nault. 2021. Potential for managing onion thrips (Thrips tabaci) in organic onion production systems using multiple IPM tactics. Insects (in press). Koirala, S., Zhao, M., Agarwal, G., Stice, S., Gitaitis, R.., Kvitko, B., and Dutta, B. 2021. Identification of two novel pathovars of Pantoea stewartii subsp. indologenes affecting Allium sp. and millets. Phytopathology (in press). Leach, A. B., F. Hay, R. S. Harding, K. C. Damann and B. A. Nault. 2020. Relationship between onion thrips (Thrips tabaci) and Stemphylium versicarium in the development of Stemphylium leaf blight in onion. Annals Appl. Biol. 176(1): 55-64. <a href="https://doi:10.1111">https://doi:10.1111/Aab.12558</a>. Leach, A., B., S. Reiners and B. Nault. 2020. Optimizing integrated pest management: A case study managing onion thrips and bacterial bulb rot in onion. Crop Prot. 133 (<a href="https://doi.org/10.1016/j.cropro.2020.105123">https://doi.org/10.1016/j.cropro.2020.105123</a>).  Mandal, S. and C.S. Cramer. 2020. An artificial inoculation method to select mature onion bulbs resistant to Fusarium basal rot. HortScience 55:1840-1847 https://doi.org/10.21273/HORTSCI15268-20. Mandal, S., A. Saxena, C.S. Cramer, and R.L. Steiner. 2020. Comparing efficiencies of two selection approaches for improving Fusarium basal rot resistance in short-day onion after a single cycle of selection. Horticulturae 6:26. doi 10.3390/horticulturae6020026. Moretti, E. A., and B. A. Nault. 2020. Onion maggot control in onion, 2019. Arthropod Management Tests 45(1): tsaa007, <a href="https://doi.org/10.1093/amt/tsaa007">https://doi.org/10.1093/Amt/tsaa007</a>. Moretti, E.A., A.G. Taylor, K. Wickings, B.A. Nault. 2021. Insights into how spinosad seed treatment protects onion from onion maggot (Diptera: Anthomyiidae). J. Econ. Entomol. doi: 10.1093/jee/toaa332. Moretti, E.A., K. Wickings, and B.A. Nault. 2021. Environmental factors and production practices that affect Delia antiqua damage in onion fields. Agric. Ecosyst. Environ. (in press 2-21-21) Nault, B., and C. Hoepting. 2020. Onion seed treatment recommendations for 2021 featuring Trigard for onion maggot control. VegEdge 16(24):  4-5. Nault, B., and C. Hoepting. 2020. Insecticide programs to consider for onion thrips control in onion in 2020. VegEdge 16(14):  8-9. Nault, B.A., L.E. Iglesias, R.S. Harding, E.A. Grundberg, T. Rusinek, T. Elkner, B. Lingbeek and S.J. Fleischer. 2020. Managing allium leafminer (Diptera: Agromyzidae): an emerging pest of allium crops in North America. J. Econ. Entomol. 113(5): 2300-2309 (https://doi.org/<a href="http://dx.doi.org/10.1093/jee/toaa128">10.1093/jee/toaa128</a>). Resende, R., A.E. Whitfield, and H.R. Pappu. 2020. Orthotospoviruses (Tospoviridae). Encyclopedia of Virology. 4th edition. Elsevier Press. In press. Sharma, S., F. S. Hay, and S. J. Pethybridge. 2020. Genome resource for two Stemphylium vesicarium isolates causing Stemphylium leaf blight of onion in New York. Mol. Plant Microbe Inter. 33:562-564. <a href="https://doi.org/10.1094/MPMI-08-19-0244-A">https</a><a href="https://doi.org/10.1094/MPMI-08-19-0244-A">://doi.org/10.1094/MPMI-08-19-0244-A</a>. Stice, P., Shin, G.Y., Armas, S.D., Koirala, S., Galvan, G.A., Siri, M.I., Severns, P.M., Coutinho, T.A., Dutta, B., and Kvitko, B. 2021. The distribution of onion virulence gene clusters among Pantoea spp. Frontiers in Microbiology https://doi.org/10.3389/fmicb.2021.00184. Stice, S., Thao, K.K., Khang, C.K., Baltrus, D.A., Dutta, B., and Kvitko, B.H. 2020. Thiosulfinate tolerance is a virulence strategy of an atypical bacterial pathogen of onion. Current Biology 30:3130-3140. Stumpf, S., Leach, L., Srinivasan, R., Coolong, T., Gitaitis, R., and    Dutta, B. 2020. Foliar chemical protection against Pantoea ananatis in onion is negated by thrips feeding.  Phytopathology 111: 258-267. Willett, D., C. Filgueiras, J. Nyrop and B. Nault. 2020. Attract and kill: Spinosad containing spheres to control onion maggot (Delia antiqua). Pest Management Science <a href="https://doi.org/10.1002/ps.5818">https://doi.org/10.1002/ps.5818</a>. Willett, D., C. Filgueiras, J. Nyrop and B. Nault. 2020. Field monitoring of onion maggot (Delia antiqua) fly through improved trapping. J. Applied Entomology <a href="https://doi.org/10.1111/jen.12740">https://doi.org/10.1111/jen.12740</a>. Woodhall, J. W., Harrington, M., Keith, S. Oropeza, A., Thornton, M. and B. K. Schroeder. 2020. First report of root rot caused by Pythium myriotylum of onion in Idaho.  Plant Disease 104:9, 2529, https://doi.org/10.1094/PDIS-05-19-0991-PDN Other Activities   <ol> <li> Abstracts and Papers at International Professional Meetings</li> </ol>       <ol start="2"> <li> Abstracts and Papers at National Professional Meetings </li> </ol>   Hua, G.K.H., and Dung, J.K.S. 2020. Use of Alliums as trap crops to reduce white rot inoculum in infested field soil. American Phytopathological Society Plant Health 2020 Meeting. ePoster presentation. August 10-14, 2020. Online meeting. Iglesias, L., and B. A. Nault. 2019. Host-plant resistance and plastic mulches: Potential for managing onion thrips (Thrips tabaci) in organic onion production. Entomological Society of America Annual Meeting, St. Louis, MO, November 20, 2019. Mandal, S. and C.S. Cramer. 2020. Advancement in breeding for Fusarium basal rot resistance of onion. HortScience 55: S22 (Abstr). Nault, B. A., R. Harding, L. Iglesias, E. Grundberg, T. Rusinek, T. Elkner, B. Lingbeek and S. Fleischer. 2019. Management of Allium leafminer (Phytomyza gymnostoma): A new invasive pest of Allium crops in North America. Entomological Society of America Annual Meeting, St. Louis, MO, November 17, 2019. Leach, A. B., S. Reiners and B. A. Nault. 2019. Integrating pest management for onion thrips and bacterial bulb rot in onion production. Entomological Society of America Annual Meeting, St. Louis, MO, November 20, 2019. Moretti, E., and B. A. Nault. 2019. Influence of abiotic factors on onion maggot adult population dynamics and larval damage in commercial onion fields. Entomological Society of America Annual Meeting, St. Louis, MO, November 18, 2019. Leach, A. B., F. Hay, R. Harding and B. A. Nault. 2019. Role of onion thrips in the development of Stemphylium leaf blight in onion. Entomological Society of America Annual Meeting, St. Louis, MO, November 20, 2019. Regan, K., and B. A. Nault. 2019. Evaluating fertilizer rates and insecticide application frequency for management of onion thrips (Thrips tabaci) on onion. Entomological Society of America Annual Meeting, St. Louis, MO, November 17, 2019. <ol start="3"> <li> Reports at Grower Meetings and Field Days</li> </ol> Drost, D. and Nischwitz, C. Onion water Use; Onion Weed Control; National “Stop the Rot” project; Onion Stand Variability; Onion Leaf Miners and other Disease Issues; and Utah Legislative Update about Agriculture.  Winter Educational Meetings: February 11, 2020. Brigham City, UT. 50 attendee’s. Dung, J.K.S. 2020. Epidemiology and IPM of white rot in Allium crops. Invited speaker. Brown Bag Seminar. Webinar presentation. August 21, 2020. Online. du Toit, L.J. 2020. Onion bacterial diseases: Knowledge gaps and a federal grant to ‘Stop the Rot’. Invited presentation, 2020 Grower Education Conference & Industry Show, Wisconsin Potato & Vegetable Growers’ Association & University of Wisconsin Division of Extension, 4-6 Feb. 2020, Stevens Point, WI. Zoom videoconference (~20 people) du Toit, L.J. 2020. Onion fungal and bacterial bulb rots, and efficacious use of fungicides for disease control in onion production. Invited presentation, AgriNorthWest farm managers, 5 Feb. 2020, Kennewick, WA (50 people) du Toit, L.J. 2020. Effective identification and management of diseases impacting vegetable crops. Invited presentation, Columbia Basin Crop Consultants’ Association Short Course, 29-30 Jan. 2020, Moses Lake, WA. (~100 people) du Toit, L.J. 2019. Bacterial rots of onion: USDA SCRI project update and knowledge gaps. Pacific Northwest Vegetable Assoc. Annual Convention & Trade Show, 20-21 Nov. 2019, Kennewick, WA. (200 people) du Toit, L.J. 2019. Effective identification and treatment of diseases impacting onion. Pacific Northwest Vegetable Assoc. Annual Convention & Trade Show, 20-21 Nov. 2019, Kennewick, WA. (200 people) du Toit, L.J. 2019. Keeping our seed pathogen-free. Webinar presented at BC Seed Gathering 2019, Kwantlen Polytechnic University, 9 Nov. 2019, Richmond, BC. YouTube recording <a href="https://www.youtube.com/watch?v=DNub-iJXbHo&t=1s">https://www.youtube.com/watch?v=DNub-iJXbHo&t=1s</a> (20 people in person + online attendance) Dutta, B., and Gitaitis, R. 2020. Bacterial Diseases of onion in Georgia. University of Georgia Cooperative Extension Bulletin B1534. Dutta, B., and Tyson, C. 2021. Evaluation of harvesting methods on post-harvest incidence of center rot and sour skin in onion, Georgia 2020. PDMR 15:V025. Dutta, B., and Tyson, C. 2021. Evaluation of digging methods on post-harvest incidence of center rot and sour skin in onion, Georgia 2020. PDMR 15:V026. Dutta, B., Tyson, C., Edenfield, J., Williams, Z., Tanner, S., Shirley, A., Reeves, B., and Powell, S. 2021. Evaluation of onion growth stage directed chemical applications and thrips management program on center rot incidence in onion bulbs in Georgia, 2020. PDMR 15:V023. Dutta, B., Foster, M. J. and Donahoo, W.M. 2021. Evaluation of fungicides to manage Botrytis leaf blight in Georgia, 2020. PDMR 14:V024. Dutta, B., Foster, M. J. and Donahoo, W.M. 2020. Evaluation of fungicides to manage Botrytis leaf blight in onion in Georgia, 2019. PDMR 14:V129. Dutta, B., Tyson, C., Edenfield, J., Williams, Z., Tanner, S., Shirley, A., Reeves, B., and Powell, S. 2020. Evaluation of onion growth stage directed chemical applications and thrips management program on center rot incidence in onion bulbs in Georgia, 2019. PDMR 14:V091. Gugino, B.K. Integrated disease management with emphasis on cucurbits, tomatoes, and onions. Beginning Vegetable Growers Meeting Series, Lewisburg, PA. 29 February 2020. Gugino, B.K. Vegetable (bacterial) disease update. Pennsylvania Department of Agriculture Inspector Training. Webinar. 27 April 2020. Hay, F.S. 2020. Current status of Stemphylium leaf blight fungicide resistance in onion in New York. Empire State Producers EXPO. Cornell Coop. Extension. Syracuse, NY. January 15, 2020.  Attendees: 43. Hoepting, C.A.  2020.  Botrytis leaf blight in onion featuring 2020 on-farm trial results and onion scouting summaries.  Potato and Onion Twilight Meeting, Cornell Vegetable Program, Marion, NY: September 3, 2020.  Attendees: 25. Hoepting, C.A.  2020.  Sneak peak at results from 2020 on-farm onion thrips research trials.  Potato and Onion Twilight Meeting, Cornell Vegetable Program, Marion, NY: Sep 3, 2020.  Attendees: 25. Hoepting, C.A. and E.R. van der Heide.  2020. Big fat onion variety nitrogen rot project. Muck Donut Hour, Elba, NY: August 18, 2020. Attendees: 9. Hoepting, C.A. 2020.  First look at 2020 results from onion thrips “hammer” trial.  Muck Donut Hour, Elba, NY: August 11, 2020. Attendees: 8 Hoepting, C.A. and S.K. Vande Brake.  2020. Onion fungicide use summaries across major muck-onion growing regions in New York.  Muck Donut Hour, Elba. NY: July 28, 2020. Attendees: 10. Hoepting, C.A. 2020. New onion fungicide recommendations for onion.  Muck Donut Hour, Elba, NY: June 23, 2020.  Attendees: 10. Hoepting, C.A. 2020. New onion fungicide recommendations for onion.  Wayne County Onion Grower Meeting, Newark, NY: June 25, 2020. Attendees: 6. Hoepting, C.A. 2020. New onion fungicide recommendations for onion.  Orange County Onion Grower Meeting, Fulton, NY: June 25, 2020. Attendees: 8. Hoepting, C.A.  2020.  Mancozeb for early BLB control in onion.  Muck Donut Hour, Elba, NY: June 2, 2020.  Attendees: 6. Hoepting, C.A.  2020.  Results from 2019 onion fungicide trials for Stemphylium leaf blight.  Orange County Onion School, Pine Island, NY: March 6, 2020.  Attendees: 50. Hoepting, C.A. 2020. 2020 Vision: New fungicide recommendations for Stemphylium leaf blight in onion.  Empire State Producers Expo, SLB Onion Fungicide Resistance Workshop.  Cornell Cooperative Extension.  Syracuse, NY.  January 15, 2020. Attendees: 43. Hoepting, C.A. 2020. The Ever-changing field performance of fungicides for control of  Stemphylium leaf blight in onion.  Empire State Producers Expo, SLB Onion Fungicide Resistance Workshop.  Cornell Cooperative Extension.  Syracuse, NY.  January 15, 2020. Attendees: 43. Hoepting, C.A.  2020.  Onion disease management: Stemphylium, downy mildew and Botrytis.  2020 Ontario County Produce Auction Meeting, Stanley, NY: January 8, 2020. Attendees: 103. Hua, G.K.H., and Dung, J.K.S. 2020. White Rot Research: USDA National Institute of Food and Agriculture Grant. Invited speakers. California Garlic and Onion Research Advisory Board Allium Research Symposium. Oral presentation February 10, 2020. Tulare, CA. (~100 attendees) Moretti, E., and B.A. Nault. 2020. Influence of environmental factors on onion maggot larval damage in commercial onion fields. Cornell Cooperative Extension. Syracuse, NY. January 15, 2020. Attendees: 50. Nault, B.A., L. Iglesias, and F. Hay. 2020. Vegetable: Update on organic onion pest and disease management. Northeast Farming Organization of New York Winter Conference Workshop. January 27, 2020. Attendees: 30. Nault, B.A. and K. Regan. 2020. Onion thrips research round-up for 2019. Empire State Producers EXPO. Cornell Cooperative Extension. Syracuse, NY. January 15, 2020. Attendees: 43. Nault, B.A. 2020. Flies in the ointment: Update on onion maggot and allium leafminer management. Cornell Cooperative Extension. Syracuse, NY. January 15, 2020. Attendees: 50. Putman, A.I Evaluation of weather-based models for management of onion downy mildew. California Garlic and Onion Symposium, UC Cooperative Extension, February 10 2020, Tulare, CA. Reitz, S. 2019. Thrips and IYSV Management in the Treasure Valley. Pacific Northwest Vegetable Association Annual Meeting. Reitz, S. 2020. Thrips/IYSV Management. Idaho-Malheur County Onion Growers Associations Annual Meeting Reitz, S.  2020. Onion Variety Day – Self Guided Tour. Malheur Experiment Station, August 2020 Thornton, M. and K. Beck. Pink root – drip applied fungicides and remote sensing. Idaho – Malheur County Onion Growers Association Annual Meeting. Ontario, OR, February 4, 2020. Thornton, M. Herbicide and growth regulator effects on single centers. Idaho – Malheur County Onion Growers Association Annual Meeting. Ontario, OR, February 4, 2020. Thornton, M. Management of pink root in onions. Idaho Association of Plant Protection, (Virtual), November 4, 2020. Thornton, M. Opportunities for insect and disease management in drip irrigated onion production. Far West Agribusiness Association Conference, Virtual, December 17, 2020. Waters, T.D., and Reitz, S. 2019. Avoiding further resistance development and insecticide efficacy for onion thrips. Pacific Northwest Vegetable Association, Kennewick, WA. Invited. (200 people) Waters, T.D. 2019. Seedcorn maggot biology and control in organic production systems. Pacific Northwest Vegetable Association, Kennewick, WA. Invited. (200 people) Woodhall, J. Stemphylium Leaf Blight Identification and Control Strategies. Pacific Northwest Vegetable Association Meeting.   <ol start="4"> <li>Newsletter Articles</li> </ol> Drost, D and Nischwitz, C. Details of February 2020 Utah Onion Association meetings published in Onion World. Available online at <a href="https://issuu.com/columbiamediagroup/docs/onion_world_may-june_2020">https://issuu.com/columbiamediagroup/docs/onion_world_may-june_2020</a> Gugino, B.K. Pennsylvania Vegetable and Berry Production: Current issues for July 14, 2020. Pennsylvania Vegetable Disease Update. <a href="https://extension.psu.edu/pennsylvania-vegetable-and-berry-current-issues-for-july-14-2020">https://extension.psu.edu/pennsylvania-vegetable-and-berry-current-issues-for-july-14-2020</a> Gugino, B.K. Pennsylvania vegetable disease update for June 17, 2020. Pennsylvania Vegetable Disease Update. <a href="https://extension.psu.edu/pennsylvania-vegetable-disease-update-for-june-17-2020">https://extension.psu.edu/pennsylvania-vegetable-disease-update-for-june-17-2020</a> Gugino, B.K. Pennsylvania Vegetable and Berry Production: Current issues for June 16, 2020. <a href="https://extension.psu.edu/pennsylvania-vegetable-and-berry-production-current-issues-for-june-16-2020">https://extension.psu.edu/pennsylvania-vegetable-and-berry-production-current-issues-for-june-16-2020</a> Putman, A.I. 2020. Vegetable disease update: disease activity continues. Imperial County Agricultural Briefs 23(3): 33-35. Putman, A.I. 2020. Vegetable disease update: winter starts wet then turns dry. Imperial County Agricultural Briefs 23(2): 21-22. Reitz, S.R. 2020. Onion Variety Day – Self Guided Tour. Malheur Experiment Station, August 2020 Walsh, O.S., Thornton, M.,  Marshall, J.M.,  Morishita, D., Felix, J. and Hatzenbuehler, P.L. 2020. Adjusting cropping systems affected by COVID-19. IPC Potato Pulse. April 24 issue. WSU Onion Alerts. <a href="https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792">https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792</a>: Time-sensitive onion disease, pest, and production topics covered in regular articles between May and August of 2020.   <ol start="5"> <li> Annual Reports</li> </ol> Beck, K., M. Thornton, R. Portenier, O. Morgan, J. Ryu and J. Neufeld. 2020. Evaluating the use of hyperspectral remote sensing and spectral vegetation indices to diagnose onion pink root. Proc. of the Idaho/Malheur County Onion Growers Meeting. 11pp Feibert, E. B. G., Reitz, S., Rivera, A., Wieland, K. D. (2020). 2019 Onion Variety Trials (pp. 21-49). Oregon State University Malheur Experiment Station Annual Report 2019, Department of Crop and Soil Science Ext/CrS 163. <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report">https://Agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report</a>  Reitz, S., Trenkel, I., Feibert, E. B. G., Wieland, K. D., Rivera, A. (2020). Evaluation of Mastercop® for Disease Management—2019 (pp. 89-91). Oregon State University Malheur Experiment Station Annual Report 2019, Department of Crop and Soil Science Ext/CrS 163. <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report">https://Agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report</a>  Reitz, S. (2020). Monitoring Onion Pests across the Treasure Valley—2019 (pp. 92-96). Oregon State University Malheur Experiment Station Annual Report 2019, Department of Crop and Soil Science Ext/CrS 163. <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report">https://Agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report</a>  Reitz, S., Trenkel, I., Feibert, E. B. G., Wieland, K. D., Rivera, A. (2020). Thrips and Iris Yellow Spot Virus Management in the Treasure Valley—2019 (pp. 97-120). Oregon State University Malheur Experiment Station Annual Report 2019, Department of Crop and Soil Science Ext/CrS 163. <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report">https://Agsci.oregonstate.edu/mes/station-complete-annual-reports/2019-annual-report</a> Thornton, M., R. Portenier, O. Adams, and B. Simerly. 2020. Long term storage of onion cultivars. Proc. of the Idaho/Malheur County Onion Growers Meeting. 4pp. Thornton, M., J. Woodhall and R. Portenier. 2020. Pink root control in onions with drip-applied fungicides. Proc. of the Idaho/Malheur County Onion Growers Meeting. 9pp. Thornton, M., R. Portenier, and O. Morgan. 2020. Evaluation of herbicides for impact on the incidence of single centers in onions. Proc. of the Idaho/Malheur County Onion Growers Meeting. 6pp. <ol start="6"> <li> Internet Resources</li> </ol> du Toit, L.J. <a href="https://www.youtube.com/watch?v=FpmGHBUezVc&feature=youtu.be">https://www.youtube.com/watch?v=FpmGHBUezVc&feature=youtu.be</a>  (English) and <a href="https://www.youtube.com/watch?v=13k5H6oTzds&feature=youtu.be">https://www.youtube.com/watch?v=13k5H6oTzds&feature=youtu.be</a>  (Spanish) videos on basic identification of onion bacterial bulb rots compared to other causes of onion bulb rots or abiotic problems. Video available in English and Spanish. Hoepting, C.A.  2020.  Cornell Cheat Sheet: Seed treatments and in-furrow drenches for muck-grown direct seeded onion.  Cornell Cooperative Extension Cornell Vegetable Program website. online: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_937.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_937.pdf</a> Hoepting, C.A. 2020.  2020 fungicide status for control of Stemphylium leaf blight in onion. Cornell Cooperative Extension Cornell Vegetable Program website. online: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_888.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_888.pdf</a> Hoepting, C.A. and S.K. Vande Brake. 2020. Cómo diagnosticar la podrición bacteriana de bulbos de cebolla. VIDEO.  Cornell Cooperative Extension Cornell Vegetable Program website. online: <a href="https://www.youtube.com/watch?v=FpmGHBUezVc&list=PLMxaHBxUI9qbChbojOUBlozWK2ypCo50p&index=2&t=17s">https://www.youtube.com/watch?v=FpmGHBUezVc&list=PLMxaHBxUI9qbChbojOUBlozWK2ypCo50p&index=2&t=17s</a> Hoepting, C.A. and S.K. Vande Brake. 2020. How to diagnose onion bacterial bulb rot.  VIDEO.  Cornell Cooperative Extension Cornell Vegetable Program website. online: https://www.youtube.com/watch?v=13k5H6oTzds&list=PLMxaHBxUI9qbChbojOUBlozWK2ypCo50p&index=3 Nault, B.A., and C.A. Hoepting. 2020. Guidelines for 2020 Management of Onion Thrips in Onion.  Cornell Cooperative Extension Cornell Vegetable Program website. online: <a href="https://cvp.cce.cornell.edu/submission.php?id=587&crumb=crops|crops|onions|crop*20">https://cvp.cce.cornell.edu/submission.php?id=587&crumb=crops|crops|onions|crop*20</a> Pacific Northwest Vegetable Extension Group (PNW VEG) website (<a href="http://mtvernon.wsu.edu/path_team/vegpath_team.htm">http://mtvernon.wsu.edu/path_team/vegpath_team.htm</a>), a tri-state Extension team with resources on diverse vegetables grown in the PNW USA. Sections on onions include the Photo Gallery (<a href="http://mtvernon.wsu.edu/path_team/onion.htm">http://mtvernon.wsu.edu/path_team/onion.htm</a>) and IPM Resources (<a href="http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion">http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion</a>). <a href="https://alliumnet.com/projects/stop-the-rot/">https://Alliumnet.com/projects/stop-the-rot/</a> website added and updated regularly to include outline and progress on the USDA NIFA SCRI 'Stop the Rot' onion bacterial disease project. Reitz, S.2020.  <a href="https://agsci.oregonstate.edu/mes/malheur-experiment-station">https://Agsci.oregonstate.edu/mes/malheur-experiment-station</a>

Impact Statements

Utah onion growers used 25% less water while maintaining onion yields when irrigation water applications were closely monitored. With data collected from local irrigation studies, improved irrigation recommendations for both furrow and drip irrigated onions are being developed. These finding are critical to Utah onion growers as water resources are projected to be in short supply in 2021

Date of Annual Report: 04/25/2022

Report Information

Annual Meeting Dates: 02/28/2022 - 03/01/2022
Period the Report Covers: 02/04/2021 - 03/01/2022

Participants

Participants Attachment:

W3008 2022 Minutes Draft 4-19-22.pdf

Brief Summary of Minutes

Minutes Attachment:

W3008 2022 Minutes Draft 4-19-22.pdf

Accomplishments

Objective 1. Evaluate onion germplasm for resistance to pathogens and insects. New Mexico (Cramer): NMSU breeding lines exhibited a lower Fusarium basal rot (FBR) incidence and severity than a commercial FBR-resistant cultivar. Other NMSU breeding lines exhibited fewer thrips/plant, lower Iris Yellow Spot Virus severity, and greater bulb size than a commercial cultivar.    New York (Nault, Hoepting, Pethybridge, Hay): Onions with semi-glossy wax leaves and low levels of H-16 ketone have shown partial resistance to onion thrips.  The semi-glossy hybrid, cv. USDA Maia, and a waxy, thrips-susceptible cv., Bradley, were evaluated on two organic farms. Season total thrips densities were similar between the two cultivars, indicating a lack of thrips resistance in USA Maia.  Bacterial bulb rot was 20-40% greater, and marketable bulb yield was 2 to 3 times less in USDA Maia, than in Bradley.  There was no relationship between season total thrips densities and incidences of bacterial bulb rot at harvest. In 2021, thrips were assessed in an onion variety trial, with an early (Apr 6) and a late (May 4) planting.  There were significant differences in thrips feeding damage among variety, and between insecticide-treated and nontreated, as well as a variety-insecticide interaction (i.e. not all varieties responded the same to insecticide treatment).  Thrips feeding caused 7% to 26% reduction in plant height.  In general, thrips feeding damage increased as days to maturity decreased, but some varieties in each maturity class had more foliar thrips feeding damage than others.  In the nontreated plots, Trailblazer, Braddock and Red Wing appeared more susceptible to thrips damage in the early, main and late maturity classes, respectively.  Crockett (118 days) had the least thrips feeding damage in the trial. Idaho (Woodhall, Thornton and Schroeder): In fall of 2020, bulbs of 10 yellow onion cultivars and pre-commercial lines were collected and stored(36oF) . On 24 May and 28 June 2021, samples were removed from storage and evaluated for defects. Seven of the ten onion cultivars and lines reached >90% marketable bulbs on the 24 May. Most non-marketable bulbs were due to internal decay and translucent scale. Caldwell, OLXY14733, and SVNW1526 had a relatively high level of translucent scale (above 8%), while Crockett, Caliber, and OLYS15-50 had less than 2%. Vaquero, the industry standard, had >95% marketable bulbs on 28 June, above the long-term average for this variety. Utah (Drost, Nischiwitz): Onion germplasm trials were conducted with two growers and evaluated for emergence, plant growth, disease and insect incidence, top down maturity, bulb yield and storage potential. Onion growth was satisfactory and disease and insect pressure was low.   Objective 2. Investigate the biology, ecology and management of onion Thrips and other pests.   Idaho (Woodhall, Thornton and Schroeder): Thrips and IYSV control with a standard foliar insecticide program (Aza/M-pede, Movento, Minecto Pro, Radiant – 2 applications of each) was compared to programs where the Movento foliar applications were substituted with 2 applications of an insecticide from Gowan (GWN-12030) applied via the drip irrigation system.  All insecticide programs reduced thrips populations and IYSV incidence compared to the untreated, and foliar and drip programs provided equal efficacy.  The proportion of ≥3-inch diameter onions was also increased by insecticide programs.   The susceptibility of bulbs from 20 onion cultivars obtained from the OSU Cultivar trial to Fusarium proliferatum was assessed. For each cultivar, 4 replicates of 20 onion bulbs were inoculated with F. proliferatum at harvest and stored for 4 months.  The trial was repeated in two consecutive years.  For evaluation, bulbs were cut down the center and assessed for percent of the surface of the bulb exhibiting rot.  In both years, cultivars Grand Perfection, 16000 and Avalon developed significantly less bulb rot (7.5-12.5%) compared to Montaro, Oloroso, Swale, Vaquero, Tucannon and Sedona (20-23.8%), indicating resistance in some commercially available cultivars.     New York (Nault, Hoepting, Pethybridge, Hay):  Combinations of fertilizer and insecticide use were evaluated for onion thrips management in 9 commercial onion fields. Thrips populations and marketable bulb yield were not affected by fertilizer treatment. The action-threshold based insecticide program controlled thrips with up to 5 fewer applications (average 2.5 fewer) than spraying weekly, with no difference in yield. Results were similar to previous years. In a small-plot trial, high rates of isocycloseram (PLINAZOLIN® technology) and cyantraniliprole provided a commercially acceptable and equivalent level of onion thrips control, and both performed better than the high rate of spinetoram. Foliar applications of PLINAZOLIN® technology provided a similar and excellent level of allium leafminer (ALM) control in scallions, as Minecto Pro. PLINAZOLIN® technology seed treatment also exhibited some activity against onion maggot. The use of spinosyn insecticides, spinetoram and spinosad, for managing allium leafminer infestations in allium crops was optimized in field trials.   Each spinosyn insecticide was applied twice, spaced either one or two weeks apart beginning at various intervals after P. gymnostoma was first detected compared to a weekly spray program. Weekly applications of either insecticide provided ≥ 98% reduction of P. gymnostoma densities in scallions and leeks relative to the untreated control. Spinetoram applied twice, regardless of initial timing and duration between sprays, provided acceptable P. gynostoma control. Spinosad also was effective when applied twice with 85 to 95% reduction in densities relative to the untreated control. Management of P. gymnostoma with spinosyns can be successful with only two applications, but control tended to be best when first applied two to three weeks after initial detection. Texas (Malla): The relationship between thrips and epicuticular wax profile of 25 germplasm accessions (including 20 from Texas A&M) was assessed. The wax compound 16-Hentriacontanone was negatively correlated (r = -0.34) with thrips per plant in 2018, but not in 2019 (r = 0.08).   Some Texas A&M germplasm entries (e.g. 31034 at Uvalde and 50014 and 50084 at Weslaco) showed tolerance (2 thrips/plant) compared to others (17-45 thrips/plant). Oregon (Reitz): Onion thrips densities and marketable bulb yield were assessed in response to nitrogen fertilization rates, and insecticides applied either weekly, at an action threshold of 1 thrips larva/leaf, or no insecticide applications. Weekly soil and tissue sampling for nutrients was conducted and nitrogen was applied according to test results for the standard treatment or at 50% of the standard treatment for the reduced nitrogen treatment. Although onion thrips were significantly lower in plots receiving a weekly insecticide application than those following an action-threshold based insecticide program, they were kept below the economic injury level of 2.2 thrips larvae per leaf.  Fertilizer rate had no significant effect on onion thrips densities.   Washington (du Toit, Waters, Pappu): Data was collected on the efficacy of broflanilide to support potential future registration for management of seed-corn maggot (Delia platura), a challenging pest for growers in the PNW.  Broflanilide worked as well as the standard spinosad treatment and offers a potential new tool to manage seedcorn maggot, which is especially important with the recent loss of the use of chloropyrifos insecticide. The product PQZ and two new yet to be labeled insecticides were compared to a local grower standard (abamectin) for control of onion thrips and IYSV. PQZ was moderately effective at controlling thrips while both numbered compounds controlled thrips as well as abamectin. The development of new active ingredients is integral to continue to control onion thrips which can quickly develop insecticide resistance.   Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens. California (Putnam, Wilson): The efficacy of fungicides for management of white rot was evaluated.  Tebuconazole applied in-furrow and penthiopyrad banded at cultivation reduced diseased bulb yield by 94% compared to the untreated.  As part of the regional USDA-SCRI Stop the Rot project, bacterial disease samples were collected from throughout California to identify bacterial species.  Bactericides and the influence of irrigation method on the incidence and severity of bacterial diseases in onions was studied. Drip irrigation reduced foliar disease and bulb rot symptoms by more than 90% compared to sprinkler irrigation.  A study in Southern California suggested weather-based fungicide scheduling can reduce fungicide applications required for onion downy mildew control under no to low disease pressure, as could application made prior to, or immediately during, favorable weather conditions.      Georgia (Dutta, Kvitko): Twelve bactericides and plant defense inducers were evaluated for efficacy against internal bacterial rot of onion. Foliar symptoms were not observed in the field or during harvest. Percent internal bulb rot incidence was significantly lower for all treatments compared with the non-treated check except for treatment with Theia, a bio-fungicide.  Bacteria from symptomatic bulbs with internal rot were confirmed as  P. ananatis. The effect of digging methods on post-harvest incidence of bacterial bulb rot in onion was evaluated. A significantly higher incidence of internal rot was observed with the straight bed-ridge undercutter compared with the chain digger. An integrated approach that included copper-bactericide, insecticide (thrips control) and herbicide programs considerably reduced center rot incidence in bulb compared to the onion grower’s standard.  Growers can achieve a profit of $880 per acre using the integrated approach identified in this project, equating to a potential profit of $8.8 million if the strategy was used over the entire onion acreage in Georgia (10,000 acres).    Two distinct secondary metabolite biosynthetic clusters associated with onion pathogenic strains of bacteria were identified, the validated phosphonate cluster (HiVir) and a putative phosphonate biosynthetic cluster (Halophos).  The pepM genes from each cluster (HiVir and Halophos) are required for onion infection by P. stewartii subsp. indologenes and P. allii, but not for millet infection by P. stewartii subsp. indologenes. Conversely, the T3SS was important for millet infection by P. stewartii subsp. indologenes but not onion infection. Induction of the intact Halophos cluster was associated with the accumulation of a necrosis-inducing factor in culture, indicative of a phytotoxin. Seven of the eleven Halophos cluster genes are required for onion necrosis phenotypes. Results indicate a Halophos biosynthetic gene cluster to be associated with onion pathogenicity in strains of P. stewartii subsp. indologenes and P. allii.   Species-specific PCR assays were validated for the detection of P. ananatis, P. agglomerans, P. allii and P. stewartii. Two P. ananatis, one P. allii, one P. agglomerans and three P. stewartii published primers as well as newly developed P. agglomerans PagR primers were evaluated for specificity against 79 Pantoea strains, comprising 15 different species.  Previously described P. ananatis-specific PANA_1008, P. allii-specific allii-leuS, and P. stewartii-specific PANST_rpoB, 3614galE, and DC283galE primers and one newly designed P. agglomerans-specific PagR primer pairs accurately identified these strains to species and, in some cases, sub-species level.  This will facilitate rapid and reliable identification of Pantoea species.   New York (Nault, Hoepting, Pethybridge, Hay):  Management of Stemphylium leaf blight (SLB) has become challenging in NY due to the rapid development of resistance to fungicides despite considerable grower adoption of fungicide resistance management strategies.  The SDH genes of 234 isolates of S. vesicarium were sequenced and 11 mutations identified, which are associated with insensitivity to FRAC 7 fungicides. Currently, the FRAC 3 fungicides are the most effective against SLB in NY. However, in vitro testing has shown a shift towards insensitivity such that disease control can only can be achieved using high rates of combinations of FRAC 3 products (e.g. Viathon + Tilt).  Other studies confirmed volunteer onion as a source of SLB.  However barley, planted between rows as a windbreak for emerging onion seedlings, was not a significant host.  Idaho (Thornton, Woodhall and Schroeder):  Pink root control from drip applications of Fontelis at the first irrigation followed by a second application 4 weeks later were compared to Velum Prime or Velum Prime followed by Minuet at the same application timings.  All fungicide programs tended to reduce both disease incidence and severity in July and August compared to the untreated.  Reduced pink root was associated with an increased onion yield.  Results confirm those of previous years which showed that Velum Prime and Fontelis applied via drip provide equal suppression of pink root.    The efficacy of various rotations of foliar-applied Provisto, Pristine, Botran, Zing!, Badge SC and Reason fungicides on incidence of decay of Vaquero yellow sweet Spanish onion bulbs after 5 months in storage was studied.  Fungicides were applied mid-July through mid-August.  Decay incidence averaged 25% in the untreated and none of the fungicide programs reduced decay incidence.   In two consecutive years, cv. Vaquero onion bulbs were inoculated after harvest with Fusarium proliferatum and cured at 25, 30, 35 or 40°C then placed at 5°C (41°F) for long term storage.  Bulbs were cut from stem to basal plate and rated for bulb rot as a percentage of cut bulb surface exhibiting symptoms.  Bulb rot was assessed at 4 and 6 months after inoculation.  For the 2 day curing durations, the bulb rot was not significantly affected by curing temperature (around 30% bulb rot).  With the 2 week curing duration the same was observed, except for the 35°C curing temperature, where more bulb rot was observed at the 4 month storage, compared to 6 month.    Oregon (Dung, Qian): Formulations of germination stimulants to control onion white rot (Sclerotium cepivorum) were studied.  Garlic oil and diallyl disulfide (DADS) was successfully encapsulated with β-cyclodextrin with greater than 90% recovery. Considerable amounts of DADS and diallyl sulfide (DAS) were detected by gas chromatography-mass spectrometry in soils 27 days post-treatment. Naturally-infested soils treated with DADS, microcapsules of DADS, and microcapsules of garlic oil exhibited 78, 76, and 77% reductions in sclerotia, respectively, compared to non-treated controls. The relative amounts and timing of DADS and DAS detected over time depended on the soil type.   The ability of onion to stimulate sclerotial germination and be used as a trap crop for white rot control was evaluated.  Infested plots were either left fallow or planted to onions which were chemically terminated at the 2-6 true leaf stages. A 24-67% reduction in sclerotia was observed when onions were terminated at the 2nd leaf stage; however, sclerotia counts were similar to fallow plots by the 3rd leaf termination timing and were greater at all subsequent termination timings.  Greenhouse trials showed similar reductions in sclerotia when onions are terminated at the 2-leaf stage.   A garlic field trial evaluated Pyraziflumid applied at 3.1, 4.6, or 6.2 oz/A in-furrow for white rot management. All rates significantly increased stand counts and plant heights and reduced disease severity compared to the control. At harvest, plots treated with Pyraziflumid at 6.2 oz/A had significantly increased marketable yields compared to the non-treated.   Utah (Drost, Nischiwitz): Fertilizer trials showed a trend that high levels of available soil K increased symptom expression of IYSV in infected onions. The percent symptomatic plants more than doubled when soil K in potash treatments increased from 125ppm to 260ppm. However, the results were not statistically significant due to variation within replications. Treatments with potassium sulfate did not increase symptom expression but plants were smaller and less vigorous than with potash treatments. In our trials, soil K affected the uptake of Fe, Mn and Zn which increased with increasing K levels in the plant tissue. However, the mechanism behind the increased IYSV symptoms is unknown.   Washington (du Toit, Waters, Pappu): Five onion fields were surveyed during the 2021 growing season for symptoms of bacterial diseases and over 75 bacterial strains were obtained (c.f. ~300 strains in the 2020 survey).  Isolates are being identified by DNA sequencing and tested for pathogenicity on onions. Selected strains have been sent to the National Onion Bacterial Strain Collection at UGA for curation and further research on genomics and mechanisms of pathogenicity.   In the 2020 WA trials, copper and other bactericide treatments had no effect on incidence or severity of bacterial bulb rot at harvest or after 5 months of storage. Trials on undercutting, rolling tops, and the timing of topping showed no significant effects on marketable yield or bacterial bulb rots. Trials indicated no benefit to applying ozone or hydrogen peroxide + peroxyacetic acid products to onion bulbs in storage for managing bacterial rots, because the products do not penetrate the dry wrapper scales into the fleshy scales where infections reside. In the 2020 irrigation trials, earlier termination of final irrigation reduced bacterial rot without affecting marketable bulb yield.   To determine the genetic diversity and evolution of IYSV, the complete N gene sequences of 142 IYSV isolates from curated sequence data in GenBank was studied. In silico RFLP analysis, codon-based maximum likelihood studies, genetic differentiation and gene flow within the populations of IYSV genotypes were investigated. Bayesian phylogenetic analysis was carried out to estimate the evolutionary rate. IYSV isolates  grouped into two major genotypes viz., IYSV Netherlands (IYSVNL; 55.63%), IYSV Brazil (IYSVBR; 38.73%) and the rest fell in neither group [IYSV other (IYSVother; 5.63%)]. Genetic diversity tests revealed IYSVother to be more diverse than IYSVNL and IYSVBR. IYSVNL and IYSVBR genotypes are under purifying selection and population expansion, whereas IYSVother showed decreasing population size and hence appear to be under balancing selection. IYSVBR is least differentiated from IYSVother compared to IYSVNL genotypes based on nucleotide diversity. Three putative recombinant events were found in the N gene of IYSV isolates based on RDP analysis. Findings suggest that IYSV continues to evolve using population expansion strategies and the substitution rates are similar to other plant RNA viruses.   Pennsylvania (Gugino) As part of the Stop the Rot SCRI project, 10 whole onion plants samples with bacterial center rot disease symptoms were collected from each of five fields at 8-9 leaf stage and again at harvest. Up to three unique bacterial colonies were selected from isolations from each plant, with 161 bacterial isolates collected and stored (-80°C). Additional samples from NY were also obtained under an APHIS 526 permit for a total of 239 additional isolates. Of the 1501 isolates collected from the field (not post-harvest), 831 were characterized to genus and pathogenicity tested. A total of 46 unique genera were identified but only five (Burkholderia, Enterobacter, Pantoea, Pseudomonas, and Rahnella) contained isolates that were pathogenic based on the red scale assay. This was similar for both PA and NY in 2020 and in 2021.   A bactericide efficacy trial was highly variable in part due to weed pressure, so treatments had no  significant effect on either foliar disease incidence or neck rot (discolored internal neck scales when the onion is topped 2 to 3 inches from the bulb) at harvest. However, the incidence of neck rot was highest in the inoculated controls (20.1%) and lowest in the ManKocide (7.3%) treatment (P=0.328). The untreated uninoculated control had 5.8% neck rot.   A nitrogen rate and timing trial with four rates (0, 50, 105, and 160 lb N/A) at two timings (half and full season) was conducted to evaluate the effect on center rot disease incidence and marketable yield. Nitrogen rate and application timing had no significant effect on the total marketable yield or size class although numerically, the highest rate of nitrogen resulted in the highest total marketable weight. Plots receiving no nitrogen during the season yielded the same as those receiving nitrogen indicating that residual soil nitrogen levels from the previous small grain crop provided enough nitrogen and likely masked any effect of the nitrogen treatments. Unfortunately, there was significant variation between replicates on both the incidence of symptomatic plants and bulbs at harvest .  More disease was observed in the inoculated plots and in those that received the standard grower recommended rate of 105 lb/A.   Objective 4.  Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management. New York (Nault, Hoepting, Pethybridge, Hay):   In 2021, 20 commercial onion fields were scouted weekly in four counties.  Incidence and severity of insects and diseases was reported and research-based recommendations provided in weekly scouting reports, including the weekly Elba Muck Donut Hour.  Presentations were made to Oregon Processed Vegetable Commission Annual Meeting,  Syngenta’s North-Atlantic Innovation 2021 Meeting, 69th Annual Muck Vegetable Growers Conference (Ontario, Canada), W-4168 Multistate Annual Meeting and Empire State Producers Expo 2021.  The ‘2021 Cornell Onion (dry bulb) ‘cheat sheet’ for control of leaf diseases’ was provided on-line. Two articles on foliar disease were published in grower magazine VegEdge.  Guided tours of the SLB fungicide trials were given to growers, crop consultants, and chemical industry representatives.   Texas (Malla): A modified insecticide program was recommended in consultation with Nault and Waters to an onion grower in the Rio Grande Valley who had difficulty controlling thrips.  Oregon (Reitz, Dung and Shock): Research was presented at the Idaho-Malheur County Onion Growers Meeting, the Pacific Northwest Vegetable Association, and the annual California Garlic and Onion Research Symposium.   Research was published online on the Malheur Experiment Station website  and Central Oregon Agricultural Research and Extension Center website.   Washington (du Toit, Waters, Pappu): The Stop the Rot onion bacterial team reached onion stakeholders through grower meetings, field days, conferences, workshops, the Alliumnet website, industry newsletters, trade publications and extension videos. Growers in each of the onion-growing regions were recruited for participation in field surveys. Stakeholder Advisory Panel members, were engaged with research activities. Panel members represent onion farms, regional onion associations, and major vegetable seed companies (including onion breeders and plant pathologists) from across the U.S., with one international member. Panel members have conducted further outreach to their own networks on behalf of the project. <ul> <li>A 15-minute extension video was released on bacterial diseases of onion and options for management in the field.</li> <li>Articles on the Stop the Rot project in the WSU Onion Alert, circulated to >600 subscribers and in Onion World Magazine.</li> <li>Lindsey du Toit’s lab assisted with diagnosis of onion samples and queries from onion growers in the PNW and other states (CA, OR, NV, ID, CO) on disease diagnosis and management.</li> </ul>   California (Putnam): The California Garlic and Onion Advisory Board held a one day symposium to update industry representatives and growers on onion research, new product updates, and facilitate discussion on industry research needs and priorities.

Publications

Agarwal, G.,  Gitaitis, R.D., and Dutta, B. 2021. Pan-genome of novel Pantoea stewartii subsp. indologenes reveals genes involved in onion pathogenicity and evidence of lateral gene transfer. Microorganisms 9: 1761. https://doi.org/10.3390/ microorganisms9081761   Agarwal, G., Choudhary, D., Stice, S.P., Myers, B.K., Gitaitis, R.D., Venter, S.N., Kvitko, B.H., and Dutta, B. 2021. Pan-genome-wide analysis of Pantoea ananatis identified genes linked to pathogenicity in onion. Frontiers in Microbiology <a href="https://doi.org/10.3389/fmicb.2021.684756">https://doi.org/10.3389/fmicb.2021.684756</a>.   Beck, K. D., Reyes-Corral, C., Rodriguez-Rodriguez, M., May, C., Barnett, R., Thornton, M.K., Bates, A. A., Woodhall, J. W., B. K. Schroeder. 2021. First report of Fusarium proliferatum causing necrotic leaf lesions and bulb rot on storage onion (Allium cepa) in Southern Idaho. Plant Disease: 2021. <a href="https://doi.org/10.1094/PDIS-06-20-1399-PDN">https://doi.org/10.1094/PDIS-06-20-1399-PDN</a>.   Brown, L., Harrington, S., Harrington, M., Murdock, M. R., Pizolotto C. A., and J. W. Woodhall. 2021. Rhizoctonia solani AG 2-2 IIIB Causing Root Rot of Onion in Idaho. Plant Disease 105:2, 498-498   Cramer, C.S., S. Mandal, S. Sharma, S. Shahabeddin Nourbakhsh, I. Goldman, and I. Guzman. 2021. Recent advances in onion genetic improvement. Agronomy 11:482. <a href="https://doi.og/10.3390/agronomy110300482">https://doi.og/10.3390/agronomy110300482</a>.   Greenway, G., N. Kamal, S. Shahabeddin Nourbakhsh, and C.S. Cramer. 2021. Estimating potential changes in costs and returns from use of a partially onion thrips-resistant cultivar and action-based spray thresholds in Idaho and Eastern Oregon. Southwestern Entomologist. 46:349-356. <a href="https://doi.og/10.3958/059.046.0206">https://doi.og/10.3958/059.046.0206</a>.   Kamal, Harding, R.S., and B.A. Nault. 2021. Onion Thrips control in onion, 2020. Arthropod Management Tests 46(1): tsab022, <a href="https://doi.org/10.1093/amt/tsab022">https://doi.org/10.1093/amt/tsab022</a>.   Hay, F.S., S. Stricker, B.D. Gossen, M.R. McDonald, D.W. Heck, C.A. Hoepting, S. Sharma, and S.J. and Pethybridge. 2022. Stemphylium leaf blight of onion: A re-emerging threat to onion production in eastern North America. Plant Dis. PDIS-05-21-0903-FE. On Just Published. 8 December 2021. <a href="https://doi.org/10.1094/PDIS-05-21-0903-FE">https://doi.org/10.1094/PDIS-05-21-0903-FE</a>.   Hay, F.S., D.W. Heck, S. Sharma, A. Klein, C. Hoepting, and S.J. Pethybridge. 2021. Stemphylium leaf blight of onion. Disease Lesson. The Plant Health Instructor R2 submitted 8 October 2021. In Press.   Hay, F.S., D.W. Heck, A. Klein, S. Sharma, C.A. Hoepting, and S.J. Pethybridge. 2021. Spatiotemporal attributes of Stemphylium leaf blight epidemics and effects of residue management in New York onion fields. Plant Dis. PDIS-07-21-1587-RE. On First Look. 19 November 2021. <a href="https://doi.org/10.1094/PDIS-07-21-1587-RE">https://doi.org/10.1094/PDIS-07-21-1587-RE</a>.   Hay, F.S., and S.J. Pethybridge. 2021. Stemphylium leaf blight of onion. Allium Chapter in World Handbook of Vegetables. In Press.   Hoepting, C.A. 2021. Running out of fungicide options for control of Stemphylium leaf blight in onion. Veg Edge, 17(18): 4-5.   Hoepting, C.A. 2021. Onion downy mildew prevention the ‘crutch’ for ‘limping’ SLB fungicides to manage DM-SLB complex. Veg Edge, 17(14): 8-9.   Hoepting, C.A. and Hay, F.S. 2021. Part II: Onion fungicide research updates and new recommendations for control of Botrytis and Stemphylium leaf blights, 2021. Veg Edge, 17(13): 8-9.   Hoepting, C.A. and Hay, F. S. 2021. Part I: Onion fungicide research updates and new recommendations for control of Botrytis and Stemphylium leaf blights, 2021. Veg Edge, 17(12): 8-10.   Iglesias, L.E., R.L. Groves, B. Bradford, R.S. Harding, and B.A. Nault. 2021. Evaluating combinations of bioinsecticides and adjuvants for managing Thrips tabaci (Thysanoptera: Thripidae) in onion production systems. Crop Protection 142 https://doi. org/10.1016/j.cropro.2020.105527.   Iglesias, L.E., M.J. Havey, and B.A. Nault. 2021. Potential for managing onion thrips (Thrips tabaci) in organic onion production systems using multiple IPM tactics. Insects (in press).   Moretti, E.A., A.G. Taylor, K. Wickings, B.A. Nault. 2021. Insights into how spinosad seed treatment protects onion from onion maggot (Diptera: Anthomyiidae). J. Econ. Entomol. doi: 10.1093/jee/toaa332.   Moretti, E.A., K. Wickings, and B.A. Nault. 2021. Environmental factors and crop management that affect Delia antiqua damage in onion fields. Agric. Ecosyst. Environ. 314:  107420.   Nault, B.A., R.K. Sandhi, R.S. Harding, E. Grundberg, and T. Rusinek. 2022. Optimizing spinosyn insecticide applications for allium leafminer (Diptera:  Agromyzidae) management in allium crops. J. Econ. Entomol. <a href="https://doi.org/10.1093/jee/toac016">https://doi.org/10.1093/jee/toac016</a>.   Regan, K. and B. Nault. 2021. Less is more: Reducing inputs benefits onion production in muck soil. Onion World  37(4): 8-10.   <ol start="2021"> <li>S. Shahabeddin Nourbakhsh, and C.S. Cramer. 2021. Reduced Iris yellow spot symptoms through selection within onion breeding lines. Horticulturae 7:12. <a href="https://doi.og/10.3390/horticulturae7060012">https://doi.og/10.3390/horticulturae7060012</a>.</li> </ol>   Koirala, S., Zhao, M., Agarwal, G., Stice, S., Gitaitis, R.., Kvitko, B., and Dutta, B. 2021. Identification of two novel pathovars of Pantoea stewartii subsp. indologenes affecting Allium sp. and millets. Phytopathology 111:1509-1519.   Mandal, S. and C.S. Cramer. 2021. Comparing visual and image analysis techniques to quantify Fusarium basal rot severity in mature onion bulbs. Horticulturae 7:156. <a href="https://doi.og/10.3390/horticulturae7060156">https://doi.og/10.3390/horticulturae7060156</a>.   Mandal, S. and C.S. Cramer. 2021. Improving Fusarium basal rot resistance of onion cultivars through artificial inoculation and selection of mature bulbs. Horticulturae 7:168. <a href="https://doi.og/10.3390/horticulturae7060168">https://doi.og/10.3390/horticulturae7060168</a>.   Mandal, S. and C.S. Cramer. 2021. Screening of USDA onion germplasm for Fusarium basal rot resistance. Horticulturae 7:174. <a href="https://doi.og/10.3390/horticulturae7060174">https://doi.og/10.3390/horticulturae7060174</a>.   Shin, G.Y., Smith, A., Coutinho, T.A., Dutta, B., Kvitko, B. 2022. Validation of species-specific PCR assays for the detection of Pantoea ananatis, P. agglomerans, P. allii and P. stewartii. Plant Disease (first look).   Stice, S., Shin, G.Y., Armas, S.D., Koirala, S., Galvan, G.A., Siri, M.I., Severns, P.M., Coutinho, T.A., Dutta, B., and Kvitko, B. 2021. The distribution of onion virulence gene clusters among Pantoea spp. Frontiers in Plant Science <a href="https://doi.org/10.3389/fmicb.2021.00184">https://doi.org/10.3389/fmicb.2021.00184</a>.   Stice, S., Thao, K.K., Khang, C.K., Baltrus, D.A., Dutta, B., and Kvitko, B.H. 2020. Thiosulfinate tolerance is virulence strategy for an atypical bacterial pathogen of onion. Current Biology 30: 1-11.    Stumpf, S., Leach, L., Srinivasan, R., Coolong, T., Gitaitis, R., and Dutta, B. 2021. Foliar chemical protection against Pantoea ananatis in onion is negated by Thrips feeding.  Phytopathology 111: 258267.  <a href="https://apsjournals.apsnet.org/doi/10.1094/PHYTO-05-20-0163-R">https://apsjournals.apsnet.org/doi/10.1094/PHYTO-05-20-0163-R</a>   Tabassum, A., S.V. Ramesh, Y. Zhai, R. Iftikhar, C. Olaya, and H.R. Pappu (2021). Viruses without Borders: Global analysis of the population structure, haplotype distribution, and evolutionary pattern of Iris yellow spot virus (Family Tospoviridae, Genus Orthotospovirus). Frontiers in Microbiology. <a href="https://doi.org/10.3389/fmicb.2021.633710">https://doi.org/10.3389/fmicb.2021.633710</a>   Woodhall, J. W., Harrington, M., Keith, S. Oropeza, A., Thornton, M. and B. K. Schroeder. 2020. First report of root rot caused by Pythium myriotylum of onion in Idaho.  Plant Disease 104:9, 2529, <a href="https://doi.org/10.1094/PDIS-05-19-0991-PDN">https://doi.org/10.1094/PDIS-05-19-0991-PDN</a>   Woodhall, J. W., Harrington, M., Brown, L., Jensen, J. and K. Painter. 2022. Development of a Real-Time Loop-Mediated Isothermal Amplification Assay for Stromatinia cepivora in Response to an Outbreak in Northern Idaho. Plant Health Progress 23:1, 24-27.   Yannuzzi, I. M., E.A. Moretti and B.A. Nault. 2021. Comparison of bioassays used to determine onion thrips (Thysanoptera: Thripidae) susceptibility to spinetoram. J. Econ. Entomol. 114(5): 2236-2240.   Zhao, M., Kvitko, B.H., Gitaitis, R.D., and Dutta, B. 2021. Bacterial streak and bulb rot of onion. Plant Health Instructor  DOI: <a href="https://www.doi.org/10.1094/PHI-E-2021-0421-01">10.1094/PHI-E-2021-0421-01</a>.   Zhao, M., Tyson, C., Chen, H.C., Paudel, S., Gitaitis, R., Kvitko, B., and Dutta. B. 2021. Pseudomonas allivorans sp. nov., a plant-pathogenic bacterium isolated from onion leaf in Georgia, USA. Systematic and Applied Microbiology 45 (1):126278. doi: 10.1016/j.syapm.2021.12627   Plant Disease Management Reports:   Belo, T., du Toit, L., Waters, T., Derie, M., and LaHue, G. 2021.  Effects of irrigation frequency and final irrigation timing on onion bacterial diseases in the Columbia Basin of Washington, 2020. PDMR 15:V109 <a href="https://doi.org/10.1094/PDMR15">https://doi.org/10.1094/PDMR15</a>   du Toit, L.J., Derie, M.L., Gundersen, B., Waters, T.D., and Darner, J. 2021. Efficacy of bactericides for management of bacterial leaf blight and bulb rots in an onion crop in Pasco, WA, 2020. PDMR 15:V107.  <a href="https://doi.org/10.1094/PDMR15">https://doi.org/10.1094/PDMR15</a>   du Toit, L.J., Derie, M. L., and Gundersen, B. 2021. Efficacy of disinfectants applied to onion bulbs in storage for control of bacterial bulb rots, Pasco, WA, 2020-2021. PDMR 15:V102. <a href="https://doi.org/10.1094/PDMR15">https://doi.org/10.1094/PDMR15</a>   du Toit, L.J., Derie, M. L., and Gundersen, B. 2021. Efficacy of late-season cultural practices on bacterial leaf blight and bulb rots in an onion bulb crop in Pasco, WA, 2020. PDMR 15:V100. <a href="https://doi.org/10.1094/PDMR15">https://doi.org/10.1094/PDMR15</a>   du Toit, L.J., M. L. Derie, B. Gundersen. 2021. Efficacy of disinfectants applied to onion bulbs in storage for control of bacterial bulb rots, Pasco, WA, 2020-2021. PDMR 15.V102.   Dutta, B., and Tyson, C. 2021. Evaluation of harvesting methods on post-harvest incidence of center rot and sour skin in onion, Georgia 2020. PDMR 15:V025.   Dutta, B., and Tyson, C. 2021. Evaluation of digging methods on post-harvest incidence of center rot and sour skin in onion, Georgia 2020. PDMR 15:V026.   Dutta, B. 2021. Evaluation of individual fungicides for downy mildew control in cucumber in Tift County, Georgia, 2020. PDMR 15:V021.   Dutta, B., Tyson, C., Edenfield, J., Williams, Z., Tanner, S., Shirley, A., Reeves, B., and Powell, S. 2021. Evaluation of onion growth stage directed chemical applications and thrips management program on center rot incidence in onion bulbs in Georgia, 2020. PDMR 15:V023.   Dutta, B., Foster, M. J. and Donahoo, W.M. 2021. Evaluation of fungicides to manage Botrytis leaf blight in Georgia, 2020. PDMR 14:V024.   Dutta, B., and Foster, M. J. 2021. Evaluation of bactericides and plant defense inducers to manage center rot of onion in Georgia, 2020. PDMR 15:V027.   Dutta, B., Foster, M. J. and Donahoo, W.M. 2020. Evaluation of fungicides to manage Botrytis leaf blight in onion in Georgia, 2019. PDMR 14:V129.   Hoepting, C.A., Caldwell, S.K., and van der Heide, E.V. 2021. Efficacy of fungicide treatments for control of Botrytis Leaf Blight and Stemphylium leaf blight in onion, Elba, 2020. Plant Disease Management Reports 15: V162.   Hoepting, C.A., Caldwell, S.K., and van der Heide, E.V. 2021. Effect of fungicide application timing on control of Botrytis leaf blight and Stemphylium leaf blight in onion, 2020. Plant Disease Management Reports 15: V163.   Hoepting, C.A., Caldwell, S.K., and van der Heide, E.V. 2021. Efficacy of fungicide treatments for control of Botrytis Leaf Blight and Stemphylium leaf blight in onion, Oswego, 2020. Plant Disease Management Reports 15: V123.   Hoepting, C.A., Caldwell, S.K., and van der Heide, E.V. 2021. Efficacy of fungicide treatments for control of Stemphylium leaf blight in onion, Elba, 2020. Plant Disease Management Reports 15: V155.   Hoepting, C.A., Caldwell, S.K., and van der Heide, E.V. 2021. Efficacy of fungicide combinations for control of Stemphylium leaf blight in onion, Elba, 2020. Plant Disease Management Reports 15: V156.   Hua, K., and Dung, J.K.S.. 2021. Comparison of fungicides for control of white rot on garlic in Oregon, 2019-2020. PDMR 15:V032.   Other Activities <ol> <li> Abstracts and Papers at International Professional Meetings</li> </ol>   Belo, T., du Toit, L., Waters, T., Derie, M., Schacht, B., & LaHue, G. (2021, 7-10 November). Combating Onion Bacterial Diseases Through Nitrogen Fertility Management [Poster Presentation]. 2021 ASA, CSSA, SSSA International Annual Meeting, Salt Lake City, UT.   MacKay et al. 2021. Combating onion bacterial diseases with pathogenomics tools and enhanced management strategies: Research objectives and preliminary results. Research on Demand presentation for American Phytopathological Society’s annual meeting, Plant Health 2021 Online, 2-6 August 2021.   <ol start="2"> <li> Abstracts and Papers at National Professional Meetings </li> </ol>   Heck, D.W., F.S. Hay, A. Klein, C. Sharma, C. Hoepting, and S.J. Pethybridge. 2021. Spatiotemporal dynamics of Stemphylium leaf blight in New York onion fields. APS NE and Potomac Division Meeting (virtual).   Heck, D.W., F.S. Hay, A. Klein, C. Sharma, C. Hoepting, and S.J. Pethybridge. 2021. Spatiotemporal dynamics of Stemphylium leaf blight in New York onion fields. APS Annual Meeting (virtual).   Lai, P.-C., L. Iglesias, and B.A. Nault. 2021. Optimizing onion Thrips management programs in organic onion production. Entomological Society of America Annual Meeting, Denver, CO, November 2, 2021.   Nault, B. A. 2021. Thrips ecology and management. In PIE Member Symposium: Four decades of adapting, advancing and transforming IPM: Honoring the career of Dr. Anthony Shelton. Entomological Society of America Annual Meeting, November 3, 2021, Denver, CO.   Nault, B. A. 2021. Impact of the Lorsban ban in onion in New York. In Symposium: The fate of chlorpyrifos in the US and beyond. Entomological Society of America Pacific Branch Meeting, April 7, 2021. Virtual.   Nourbakhsh, S.S. and C.S. Cramer. 2021. Evaluating onion breeding lines for thrips numbers and plant size when grown using water deficient conditions. HortScience 56: S106.   Qian, Y.P., Dung, J.K.S., Hua, G.K., and Qian, M. 2021.  Encapsulation of garlic oil and diallyl disulfide with β-cyclodextrin for garlic white rot control. American Chemical Society Spring 2021 Meeting. Poster presentation. April 5-30, 2021. Virtual.   Regan, K.H., and B.A. Nault. 2021. Less is more: Evaluating reduced applications of fertilizer and insecticide use for management of onion thrips (Thrips tabaci) on onion. Entomological Society of America Annual Meeting, Denver, CO, November 3, 2021.   Regan, K.H., and B.A. Nault. 2021. Less is more for onion management: Reducing inputs pays off in integrated pest management programs for onion thrips (Thrips tabaci). Entomological Society of America Eastern Branch Meeting, Virtual Format. March 2021.   <ol start="3"> <li> Reports at Grower Meetings and Field Days</li> </ol> Chitturi, A., Feibert, E. B. G., Wieland, K. D., Reitz, S. 2021 Management of Onion Thrips with Threshold-Based Insecticide Applications and Reduced Nitrogen Fertility–2020 (pp. 170-181). Oregon State University <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report">https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report</a>.   Drost, D. 2020. Utah Onion Variety Report. Utah Onion Association meeting, Brigham City, UT   Feibert, E. B. G., Reitz, S., Wieland, K. D. 2021. 2020 Onion Variety Trials (pp. 39-61). Oregon State University <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report">https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report</a>.   Gugino, B.K. Vegetable pathology program update (included onion bacterial disease projects). Lehigh Valley Vegetable Meeting (webinar). 25 May 2021.   Gugino, B.K. Vegetable field walk (covered onion diseases). Juniata County Vegetable Twilight Meeting. Richfield, PA. 27 July 2021.   Gugino, B.K. Identification and management of common foliar and bulb diseases of onion. Keystone Family Farms Onion Meeting. Madisonburg, PA. 24 January 2022.   Gugino, B.K. Identification and management of common foliar and bulb diseases of onion. 2022 Mid-Atlantic Fruit and Vegetable Convention. Hershey, PA. 1 February 2022.   Hay, F., Heck, D., Hoepting, C., Klein, A., Pethybridge S.J. 2021. Stemphylium leaf blight – Current status of fungicide insensitivity.  Update for W3008 Multistate Project Annual Meeting, February 3, 2021 (by Zoom).   Hoepting, C.A.  2021.  Tour of on-farm Oswego onion fungicide trial, Oswego, NY: August 27, 2021 (11 participants).   Hoepting, C.A.  2021.  Tour of on-farm Elba onion fungicide trials, Elba, NY: August 24, 2021 (9 participants).   Hoepting, C.A.  2021. New onion fungicide recommendations for 2021.  Annual Oswego County Onion Growers Twilight Meeting, Oswego, NY: June 24, 2021 (51 participants).   Hoepting, C.A.  2021. New onion fungicide recommendations for 2021.  Elba Muck Donut Hour, Elba, NY: June 22, 2021 (8 participants).   Hua, K., and Dung, J. 2021. Comparison of Fungicides for Control of White Rot on Garlic in Oregon, 2019-2020. Central Oregon Agricultural Research and Extension Center 2020 Annual Report:17-18. <a href="https://agsci.oregonstate.edu/sites/agscid7/files/assets/coarec_annual_report_2020_updated.pdf">https://agsci.oregonstate.edu/sites/agscid7/files/assets/coarec_annual_report_2020_updated.pdf</a>   Hua, K. and Dung, J. 2021. Use of Alliums as Trap Crops to Reduce White Rot Inoculum in Infested Soils. Central Oregon Agricultural Research and Extension Center 2020 Annual Report:19-20. <a href="https://agsci.oregonstate.edu/sites/agscid7/files/assets/coarec_annual_report_2020_updated.pdf">https://agsci.oregonstate.edu/sites/agscid7/files/assets/coarec_annual_report_2020_updated.pdf</a>   Nault, B.A. 2021. Onion Thrips update and maggot control in a world without Lorsban. Great Lakes Fruit, Vegetable and Farm Market EXPO. Grand Rapids, MI. December 8, 2021. Virtual Speaker, 45 min.   Nault, B.A. 2021. Onion maggot management in the Great Lakes region. Agriculture and Agri-Food Canada’s Pesticide Reduced Risk Webinar for Root Pests of Carrot and Onion. (Ontario, Canada). Virtual. November 30, 2021. Speaker, 25 min.   Nault, B.A. 2021. Update on management tactics for onion insect pests in New York. Sixty-ninth Annual Muck Vegetable Growers Conference (Ontario, Canada). Virtual. April 1, 2021. Speaker, 25 min.   Nault, B.A. 2021. New York vegetable entomology update. Syngenta’s North-Atlantic Innovation 2021 Meeting, March 16, 2021. Virtual. Speaker, 15 min.   Nault, B.A. 2021. Seedcorn maggot biology and management in vegetable crops with an emphasis on seed treatments. Oregon Processed Vegetable Commission Annual Grower Meeting. Virtual. January 25, 2021. Speaker, 40 min.   Nault, B.A. 2021. Past, current and future management of onion maggot using seed treatments. New York State Report for the W-4168 Multistate Annual Meeting, October 15, 2021. Geneva, NY. Speaker, 20 minutes.   Nischwitz, C. 2021. Stop the Rot: Update on Utah’s Survey and Field Trials. Utah Onion Association meeting, Brigham City, UT   Nischwitz, C. 2021. Utah’s Disease Survey and Field Trials. Onion Association Field Day, Ogden, UT   Regan, K. and B. Nault. 2021. Less is more: Reducing inputs pays off in muck onion systems. Cornell Cooperative Extension Presentation, Elba Muck Donut Hour, Elba, NY. 10 August 2021. Co-author, 20 minutes.   Reitz, S. 2021 Monitoring Onion Pests across the Treasure Valley–2020 (pp. 138-144). Oregon State University <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report">https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report</a>.   Reitz, S., Feibert, E. B. G., Wieland, K. D. 2021 Effects of Irrigation and Nitrogen Fertility Management on Bulb Rots in Onion–2020 (pp. 158-169). Oregon State University <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report">https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report</a>.   Reitz, S., Wieland, K. D., Feibert, E. B. G. 2021 Management of Bacterial Bulb Rots in Onion–2020 (pp. 145-152). Oregon State University <a href="https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report">https://agsci.oregonstate.edu/mes/station-complete-annual-reports/2020-annual-report</a>.   Schroeder, B. K. 2021. Bacterial Diseases of Onions. Idaho and Eastern Oregon Crop Protection Meeting. Virtual Feb. 2, 2021.    Schroeder, B. K., Sankaran, S., and Khot, L. FAIMS (Field asymmetric ion mobility spectrometry) Detection of Bulb Rot Pathogens in Storage. Idaho and Malheur County Onion Growers’ Association 60th Annual Meeting. Feb. 4, 2020.    Thornton, M. 2021. Soil-borne diseases. Idaho and Eastern Oregon Onion Crop Protection Meeting, virtual, February 2, 2021.   Thornton, M., N. Olsen, R. Hendricks and L. Woodell. 2021. Pre-harvest bruise factors. AgriNorthwest Agronomy Team Meeting, virtual, February 3, 2021.   Thornton, M. 2021. Pink root and single centers in onions. AgriNorthwest Agronomy Team Meeting, virtual, February 3, 2021.   Thornton, M., R. Portenier, O. Morgan, K. Beck and B. Simerly.  2021.  Long term storage of onion cultivars.   Proc. of the Idaho/Malheur County Onion Growers Meeting. 4pp.   Thornton, M., J. Woodhall, R. Portenier, K. Beck and O. Morgan.  2021.  Pink root control in onions with drip-applied fungicides.   Proc. of the Idaho/Malheur County Onion Growers Meeting. 6pp.   Woodhall, J. Onion disease update, featuring bacterial diseases. 2021. Idaho-Malheur Co. Onion Growers Meeting, Nampa. February 1, 2022   Woodhall J. Stemphylium leaf blight: a re-emerging disease of onions?  U of I, EPPN departmental seminar. 12th April 2021.   Woodhall J. Stop the Rot: Diagnostic and Survey Results. PNW Vegetable Association meeting 2021. 17th November. Kennewick.   Woodhall J. Use of Models and Trapping in Pest Management. PNW Vegetable Association meeting 2021. 18th November. Kennewick.   Woodhall J. Foliar diseases of onion in the Treasure Valley. Onion Crop Protection Meeting. Virtual. February 2nd 2021   <ol start="4"> <li>Newsletter Articles</li> </ol> Cramer, C.S. and I. Guzman. 2021. Breeding for resistance to Iris yellow spot. Onion World. July/August, pp. 10-13. Drost, D. 2020. Bouncing Back. Onion World Vol. 36(4):6-7. <a href="https://onionworld.net/magazine/">https://onionworld.net/magazine/</a>   Drost, D. 2021. Utah Growers Zoom in on Latest Research. Onion World Vol. 37(4):6-7. <a href="https://onionworld.net/magazine/">https://onionworld.net/magazine/</a>   Drost, D. 2021. Utah State Heads to the Shed and On to Outside. Onion World Vol. 37(7):30-31. <a href="https://onionworld.net/magazine/">https://onionworld.net/magazine/</a> du Toit, L.J., Waters, T., Derie, M., and Darner, J. 2020. Battling onion bacterial diseases with bactericides. Onion World, December 2020:6-11. <a href="https://issuu.com/columbiamediagroup/docs/onion_world_december_2020">https://issuu.com/columbiamediagroup/docs/onion_world_december_2020</a>. du Toit, L., and Waters, T. 2021. To disinfect or not? Can postharvest applications of disinfectants reduce bacterial bulb rots in storage? Onion World, July/August 2021:6-9. <a href="https://issuu.com/columbiamediagroup/docs/onion_world_july-august_2021/6">Onion World Magazine July/August 2021</a> Dutta, B., Grey, T., and Schmidt, J. 2022. Neglecting weeds can lead to late-season disease in organic onions. Specialty Crop News. March 2022.   Dutta, B., DevKumar, G., Kvitko, B.H., and Naikare, H. 2021. Studying Salmonella contamination in onion. Vegetable and Specialty Crop News, August 2021.   Dutta, B. 2021. Onion disease management in Georgia. Vegetable and Specialty Crop News, February 2021.   Dutta, B and Gitaitis, R.D. 2020. Disease quiz II. Onion World Magazine. January 2021.   Dutta, B and Gitaitis, R.D. 2020. Disease quiz I. Onion World Magazine. July 2020.   Gugino, B.K., K. Demchak, and S. Fleischer. 2021 PA Vegetable and Berry Production: Current issues: June 10. Online: <a href="https://extension.psu.edu/2021-current-issues-for-pa-vegetable-and-berry-crops-june-10">https://extension.psu.edu/2021-current-issues-for-pa-vegetable-and-berry-crops-june-10</a>   Gugino, B.K. 2021 Pennsylvania Vegetable Disease Update: June 23 Online: <a href="https://extension.psu.edu/2021-pennsylvania-vegetable-disease-update-june-23">https://extension.psu.edu/2021-pennsylvania-vegetable-disease-update-june-23</a>    Gugino, B.K., K. Demchak, and S. Fleischer. 2021 PA Vegetable and Berry Production: Current issues: July 6. Online: <a href="https://extension.psu.edu/2021-pa-vegetable-and-berry-current-issues-july-6">https://extension.psu.edu/2021-pa-vegetable-and-berry-current-issues-july-6</a>   Gugino, B.K. 2021 Pennsylvania Vegetable Disease Update: July 14 Online: <a href="https://extension.psu.edu/2021-pennsylvania-vegetable-disease-update-july-14">https://extension.psu.edu/2021-pennsylvania-vegetable-disease-update-july-14</a>   Hoepting, C.A.  2021.  2021 Cornell Onion (Dry Bulb) Fungicide Cheat Sheet for Control of Leaf Diseases.  Cornell Cooperative Extension Cornell Vegetable Program. Website: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_982.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_982.pdf</a>   Hoepting, C.A.  2021.  Example Onion Fungicide Spray Program for Control of Leaf Diseases in Onion, 2021.  Cornell Cooperative Extension Cornell Vegetable Program. Website: <a href="https://rvpadmin.cce.cornell.edu/uploads/doc_984.pdf">https://rvpadmin.cce.cornell.edu/uploads/doc_984.pdf</a>   Hua, G.H.H. and Dung, J.. 2020. Here Today, Gone Tomorrow: Can Early Terminated Onion Trap Crops Reduce White Rot Infestations? Onion World (November 2020):32-33.   Lameiras, M.M. 2020. UGA researchers discover genes that allow bacteria to resist onion’s natural defenses. CAES News and Events, July 2020.   Mazzone, J.D. and B.K. Gugino. 2021. What have we learned from two decades of onion cultivar research at Penn State? Online: <a href="https://extension.psu.edu/what-have-we-learned-from-two-decades-of-onion-cultivar-research-at-penn-state">https://extension.psu.edu/what-have-we-learned-from-two-decades-of-onion-cultivar-research-at-penn-state</a>.   Nischwitz, C. 2021. Bacterial Bulb Rot Diseases in Utah. Utah Pests Quarterly. Spring edition. Vol. 15: 11 and 15. (<a href="https://extension.usu.edu/pests/files/up-newsletter/2021/UtahPestsNews-spring21.pdf">https://extension.usu.edu/pests/files/up-newsletter/2021/UtahPestsNews-spring21.pdf</a> )   Robinson, A. 2020. Fungicide Update for Vegetable Crops. Vegetable and Specialty Crop News, March 2020.   Thompson, C. 2020. Organic Vidalia Onion Industry: Challenges in sour skin management. Onion World Magazine. December 2020.   Thompson, C. 2020. Vidalia onion crop looks ‘favorable’ despite presence of downy mildew disease in localized areas. Vegetable and Specialty Crop  News, April 2020. (edits provided by B. Dutta)   Woodhall JW, Murdock M, Beck K, Thornton . Pink root of onion. University of Idaho Extension press. BUL 1000. <ol start="5"> <li> Annual Reports</li> </ol> LaHue, G.T., Waters, T., and du Toit, L., 2020. Revisiting nitrogen management recommendations in the context of onion bacterial diseases. Progress report Columbia Basin Onion Research Committee. Submitted 31 October 2020. <ol start="6"> <li> Internet Resources</li> </ol> Wohleb, C.H., Waters, T.W., du Toit, L.J., and LaHue, G. 2021. Washington State University Extension Onion Alert, 1 September 2021. <a href="https://mailchi.mp/wsu/wsu-onion-alert-sept1-2021-1305808?e=72ba613792">https://mailchi.mp/wsu/wsu-onion-alert-sept1-2021-1305808?e=72ba613792</a>  du Toit, Lindsey, MacKay, Heather, Kilgore, Darrell, and Ziegler, Matthew. Combating bacterial diseases of onion: How do we stop the rot? 14.41 min. Posted Dec. 15, 2020. <a href="https://youtu.be/VLpZqCrQuPw%20(1,613">https://youtu.be/VLpZqCrQuPw</a>

Impact Statements

The nation-wide Stop the Rot project is developing management practices for bacterial diseases in onion bulb crops, and is benefitting onion growers across the USA and internationally. Molecular diagnostic tools being developed and tested in the ‘Stop the Rot’ project will help farmers to quickly identify the particular pathogen causing bacterial disease in their crops, and ascertain the threat it poses to the crop. New information for managing and reducing the risks of bacterial disease using improved irrigation, fertility, cultural and bactericide treatments has been developed. Several treatments currently in use for preventing internal bacterial bulb rots in storage were identified as ineffective, and this could offer potential financial savings to producers.