Brief Summary of Minutes of Annual Meeting

1) Call to Order-8:10 AM. Jeff M. passed around a printout of the roster, noting that the contact for several of those listed was out-of-date. Roster at: http://nimss.umd.edu/homepages/member.cfm?trackID=7516. Members should check & update this information. 2) Introductions 3) Approval of Agenda-No formal additions. 4) Correction/Approval of 2008 Minutes-one correction, for Idaho Report, Doug Boze should replace Greg Boze. Approved (I/II - Dan Hane/Doug Boze). 5) Report of the Western Association of Ag Experiment Station Directors (WAAESD) Administrative Advisor (Dr. Greg Bohach)- Mid-term Impact Statement will need to be prepared. This year is of special significance because it is a WAAESD review year. A fairly routine procedure, but of importance because it ensures the continued existence & funding for the project. Awards for the committee in 2008 included the regional WAAESD Outstanding Multidisciplinary Research Award. Certificates given to each member listed on the official roster (NIMSS System). Group did not get the national award but Greg encourages the group to apply again this year & feels the group stands a good chance to achieve this award. It includes national recognition, attendance at the national award meeting, & financial incentives to the group to fund guest speakers, etc. There is a very short turn around time to get this going. 6) Report of Seed Certification Personnel Oregon-Jeff M. reported it was a relatively 'average' year for Oregon in terms of acreage & disease levels observed in field & winter grow-outs. Growers struggled to find a replacement for the Alberta seed sources they had planned to plant but were not available due to the nematode situation. Alberta seed has become an increasingly important source of clean seed for Oregon growers. Varieties grown continued to diversify away from Russet Norkotah & Russet Burbank into several of the PVMI & Colorado varieties, but no replacement for Shepody was available. Idaho-Doug B. passed out a handout entitled 'Summary of Winter Test Plots 2002-2008'. Mosaic was stable in 2009 with a decrease in the number of ineligible lots. Rob Davidson felt the ID data showed that the seed programs were, by & large, working to keep virus down, though some failures still occur (as with R. Norkotah). Q:(Rob D.)Was the decrease in ineligible lots related to reduction in R. Norkotah lots? In Colorado they found that growers of R. Norkotah lots (and other latent varieties) had virus problems in all their varieties & when they quit growing R. Norkotah, PVY issues slowly went down, thus showing that these types of varieties should not be in the system! A:D. Boze)RN definitely a factor in management of mosaic in Idaho, PVY/PVA ELISA testing of all WGO lots is likely helping. No visual assessment is made of the lots, so any strains not giving +ELISA reaction would be missed. Q: Is PVA a problem? A:(Phil N.)Essentially all Mosaics were PVY not PVA, there are a few 'pockets' of PVA in Idaho but PVA does not seem to spread like PVY. Jonathan W. noted that basically 'you have to buy PVA' in the seed to get it. A discussion on the differences between PVY & PVA followed. Data has shown that infection rates for PVY & PVA were 80% vs. 20% in similar field environments. Thus reduced plant-to-plant transmission may be involved. Steve M. pointed out that some PVA strains can be very virulent, as described in Slack's paper in the 1990s. It was noted that if PVA kills the host plants, that may actually reduce plant-to-plant spread in the field. The host range of PVA is also narrower than PVY, thus reducing the amount of over-wintering host plant sources of PVA. Jorge A. pointed out that the aphid vectors are also different for these two viruses as well as their preferred host plants. Q:(Phil H.)Is Shepody was still considered a problem in regards to PVY management? A:yes. He noted cases in Oregon where Russet Burbank & Shepody fields with the same virus levels in the beginning of the season (and similar aphid exposure), were radically different at the end of the season, with mosaic levels in Shepody much greater than in RB. This has lead him to believe that the virus actually increases faster in Shepody than in RB plants. Q:(Mike T.)Do you follow the ineligible lots to see how they perform relative to eligible lots then next season? A:(Doug B.)No. Mike noted that anything over 0.5% should not be planted as seed. Q:(Phil H.)Are there areas in Idaho with more mosaic problems than others? A:(Doug)Yes, there are seed control districts & most of the 'problem areas' are outside these control districts. Q:(Phil H.)Have there been any PLRV issues in the seed lots in general? A: No, little PLRV was observed by any of the Agency present in 2008. Q:(Nina Z.) Was Idaho's ELISA program for summer lots? A: No just the WGO, where leaves from all 400 emerged plants (Idaho's standard lot size) are bulked by 5 & tested. In the summer program, all plants scored for mosaic are flagged, sampled, & tested for PVY & PVA also. Initially Idaho did a comparative test between visual & ELISA testing of the WGO and based on the results, switched over to an ELISA only system. Overall Idaho has been pleased with the ELISA only system for PVY/PVA in the WGO. Q:(Steve M.)What is the basis of the 400-tuber standard sample size in Idaho? A:(Doug B/Phil N.)The switch was somewhat imposed as a cost saving measure but was also based on work done by RE Lund & Mike Sun in 1985 ('Sample size determination for seed potato certification' Am. Pot. J. (62) 347:353) that showed little benefit in determining the accuracy of the % virus in the lots above the 400 tuber level. Steve M. pointed out that this conclusion assumed a truly random sample, which may not be the case for very large acreage lots if only 400 tubers are taken. Larger WGO lot sizes may better represent the entire lot (i.e. be more 'random'). In Idaho, they felt the cost saving of the 400-tuber standard lots size outweighed the potential drawbacks of not having a larger sample size. The concept of A & B samples for the WGO as also discussed (A=primary sample, B=backup sample in case of challenges on the results of the A sample). Kent S. pointed out that this system has worked well in solving grower challenge issues in Colorado, & that in general the B sample results confirmed the results of the A samples. Colorado-Kent S. presented slides showing the acreage change of several states from 1995 to 2008. Most were down (ND, WI, MI, ID) some were up (CO) some about the same (MT). Q:(Gary Franc)Does this downward trend means supply is down (short) or need is down; are adjustments needed? A:(Rob D.)Part of the reason acreage is down is that many of the 'poor growers' who produced rejected lots are no longer in the system, thus meaning that more of the acreages entered are accepted. (less 'lost lots'). In Colorado anyway, they have fewer growers & less acreage, but more 'serious/better growers'. An increase in seed yields over time has also helped offset acreage loss. Colorado, Nebraska, & Wisconsin are in the process of implementing a state seed law (i.e. requiring all potato acreage to be planted with certified seed). All other potato seed states have seed laws in place. Phil N. noted that Idaho has a seed law, but it is not well enforced, & some folks still 'get burned' planting uncertified seed. Although the initial seed laws were put in place to help control Bacterial Ring Rot, it was felt by the group that such 'certified seed only' requirements also help keep PVY under control (albeit to a lesser degree than BRR). Phil N. noted that no system is perfect but the primary issue is that 'what is sold needs to be controlled', not necessarily what is kept on the farm & not sold.. Kent also showed a slide on acres entered vs acres accepted 1975-2005. There was a steady increase in acres entered. Three periods of high rejections were noted: (1) late 1970 where PLRV rejections predominated; (2) early 1980 where Bacterial Ring Rot was a problem; (3) 2000-08 with rejections rising due to PVY. He also pointed out the years Russet Norkotah was introduced was not the year PVY issues stated, it took several years for the PVY inoculum to build up & cause general wide-spread problems. The BRR problem was caused when a commercial warehouse was used to store seed & exposed several seed lots to BRR, resulting in a very aggressive push by certification & the industry to control this disease in seed lots (many stars in the book). Development of good & fast test methods for this disease, implementation of the flush through system, & use of tissue culture, has created the overall control of BRR in Colorado (as else where). The move from many small farms to fewer & larger operations has also helped. Q:(Jeff Mc)What are the Russet Norkotah acreages being replaced with? A:(Kent/Rob D.)Many of the new PVMI varieties (Canela Russet, Classic Russet, Blazer Russet). Any early variety with good grade out & that have PVY resistance (but showing good PVY symptom expression) are potentials. Kent was particularly impressed with Classic Russet noting a case where a late-planted, late-harvested lot (which made it prone to getting PVY) ended up with very little mosaic in the WGO. Jonathan W. noted that Classic Russet is the perfect variety for PVY control because it has good resistance & good symptom expression allowing PVY to be rogued when present. Dan H. noted that Shepody is still an issue in PVY management because, as of yet, there is no good replacement for this very early processor. Colorado is still only a PVYo state, though PVYo5 strain (that gives a positive to PVYn antisera) is causing problems with shipments to Mexico(Alex talks about this more, see accompishments). PVYn may be present but is not at all widespread. Alex noted that any program that only uses monoclonals for PVY-ELISA detection could select for this problem. Q:(Phil H.)Are certification agencies routinely doing PVY strain surveys? A: No, because this PVY strain identification is not part of states standards, & most programs are based on visual mosaic (i.e. they only need to be sure the mosaic is viral caused, not which strain causes it). Above all, there is not yet available & affordable diagnostic test that differentiates all occurring strains. Q:(Mike T.)Has the Late Blight quarantine in CO has worked to limit this disease in CO? A:Yes, it seems to have worked. There are a few incidences but no blowups. Organic growers in areas of commercial potato sprayed for LB have seen less LB in their tomato crops, which Rob Davidson felt was due to a reduction of LB spores in the area. Montana-Nina Z. reported that her official year began in October, but she had spent part of the summer visiting growers in Montana. No PLRV was observed in 2008. The Winter Grow-out results pretty much mirrored the summer readings, with just a few downgrades or rejections. Russet Norkotah is still a problem for some growers in regards to PVY. Keeping levels below 2% can be challenging for these growers (no surprises). They do have one grower who has never had a +PVY in his Norkotah lots, he lives in an area with very severe winter weather, so this might help. Q: What is the tolerance for PVY in the Montana WGO. A: The WGO levels are for the grower's information only, they can advise the grower, but not reject lots based on the WGO level. They do have a 0.5% Mosaic limit for re-certification. Nebraska-Steve M. reported this was a good year for Nebraska lots, with few rejected. Nothing new to report. They note that mosaic occurred in previously 'clean' seed lots while grown near wild plum & chokecherry trees that occurs in hedgerows. Washington-Andy Jensen was present but had nothing to report. North Dakota-(this was given by Nick David on Thursday)N. Dakota & Minn. had a very wet spring & summer, resulting in much of the crop not being harvested this year. WGO results of 373 lots from ND & MN showed 80% of lots entered were eligible for recertification, 60% had no detectable virus. ND has very few Russet Norkotah so PVY is not as big of an issue in this state as other areas. PMTV is present, but not a problem. MN has not had a major problem with TRV. It is in 4 regions of the state but low volume applications of Vydate 4 times in the early season 3 weeks apart are effective in controlling the nematode vector. Discussion on how the depth of penetration affects the efficacy of Oxamyl in control of stubby-root nematode followed. It was noted that the nematodes follow the roots, so if the previous crop was a deep-rooted crop like corn, the Oxamyl would only be effective if it reached fairly deep into the soil. Othello & Hermiston Commercial Seed Lot Plots-Phil Hamm reported on strains studies done at the Othello & Hermiston Commercial Seed Lot Plots that showed most mosaic found were PVYo, though some PVYno, PVYn, & PVYntn was also present. Owners of these lots were notified. Incidence of PVYno was down. Alex pointed out that in France the reverse is true, that there was more PVYn than PVYo. Another report on the Othello Seed lot trials was given by Mark Pavek (see Accompishments). A Series of research updates were provided by the following(see accomplishments): Phil Nolte, Alex Karasev, Jonathan Whitworth, Darrin Hall, Phillip Hamm, Mark Pavek, Juan Alvarez, & Steve Marquerdt. Needed Research should include: 'Work on vectors & alternative host known to transmit/harbor PVY' & 'Improvement in practical detection methods for PVY & PVY strains'. 9) Additional Business Greg Bohach addressed the group about (1) the need to prepare the report for this year; (2)the need to have the 2008 publications related to WERA089 of each participant included in the minutes (see publications); (3) Update individual member profile information on the NIMSS web site. (both the 'Appendix E: Participation' & 'Participants Directory') (http://nimss.umd.edu/homepages/home.cfm?trackID=7516). Jeff had circulated a printout of the current 'Participants Directory' information on the NIMSS site so members could see who & what was posted. Q: Should the NVMP be included in the list of publications? A: Probably not, it would be listed under impacts. It is important that these are updated, & the Impact & Accomplishment of the group be documented, because this is the 5 year project review & it will either be extended or disbanded based on this review. a) Impact & Accomplishment Statements - What is noted below refers to the items for the 'Submission Form for WAAESD Impact Statements' form that was handed out. Impact Nugget: The research & extension work done by this dynamic multidisciplinary committee has resulted in the characterization of critical emerging virus & virus-like problems that are threatening to impact potato production, exports, & global competitiveness of the United States. Issue: Stakeholders, consumers, & producers of the 4th ranked food crop in the US production & the most widely consumed vegetable. Specifically those benefited from the groups actions include: federal agencies, state & commodity commissions concerned with potato crops, Potato Association of America & the US Potato Board, potato grower associations, potato producers & consumers, potato marketing & trade groups. What has the project done so far?: Facilitating collaboration & maintaining dialog in the use & development of an array of state-of-the-art techniques used to address the problems associated with potato viruses, including scoping surveys, vector management, serological techniques, symptom identification, grower education, & fostering conferences. Impact Statements: 1. BLTVA: Role of psyllids in transmission of BLTVA & development of control strategies for the disease caused by this pathogen. 2. PVY Characterization: Identification of a new 1F5 antibody for accurate characterization of the 'O5' strain of PVY & refinement of the interactions between potato variety, PVY strains, & methods of inoculation. 3. Necrotic Virus Management Plan: Revised & updated, based on data obtained through the bi-lateral Scoping Survey work, thereby allowing trade between US & Canada to continue uninterrupted. 4. TRV/CRS work: Detection of the presence of TRV in states outside the Pacific Northwest, recognition of new symptoms, & recommending Vydate based control measures for this nematode-virus complex. Research Needs for Future Impacts: 1. Survey of virus strains & work on how they impact management of viruses. 2. Descriptions of foliage & tuber symptom expression of various viruses & virus strains in the potato cultivars grown in the US. 3. Improvement to the detection & characterization tools used for new strains of virus, & the development of practical, applied, large scare, tests for potato plants & tubers. b) Grant submissions-Greg went on to say the group neededs to rewrite the proposal for WERA089. It is due in 2010. Juan asked why it was important to get USDA approval for this group. A: States receive Hatch Act money, of which 25% must be used for activities like this group (i.e. to help defray travel expenses, etc.). In addition, having a recognized WERA title helps to 'legitimize' the group & makes it easier for those traveling on non-Hatch Act funds to get travel approvals for attending it's meetings, as well as receiving University recognition for their involvement. Other Items: Greg asked if the group wanted to try for the 'Outstanding Multidisciplinary Resource Award' in 2010. Details & the criteria for this award are listed on the ESCOP web site: http://escop.ncsu.edu/. The answer was 'yes' & a committee made up of Phil N., Phil H., Rob D., Gary F., Alex K., & Steve M. was formed to move the process along. Greg also mentioned that the minutes for this meeting must be approved & posted within 60 days, & should include publication reference citations of group members for 2008. Lastly, Greg asked what to do with the plaque received for the regional 'Outstanding Multidisciplinary Resource Award' last year. A: It should be kept with the 2010 Chair (Stewart Grey). It will help remind him to organize the 2010 meeting! Tuber testing for tuber necrosing viruses: Kent Sather asked the group about where they were sending samples (of tubers) to test for Necrotic Virus as mandated in the NVMP. He knew that Jim C. had been doing this but needed to back off the routine testing work. Currently Western Labs & Agdia are offering this service. Kent noted that they had had some unacceptable delays when they asked Western Labs to run this test (truck waiting at the border). Phil H. mentioned that they could run a limited number of these tests quickly if it was an emergency situation. 10) Election of Secretary Joseph Munyanza was unanimously elected Secretary (I/II Gary F./Juan A.) 11) 2010 Meeting Location & Date - after several suggestions, consensus was that the 2010 meetings be held in Tucson. The same hotel would be fine (though not required, the Best Western across the street was suggested as another option). Juan suggested that the chair negotiate with the hotel to see if we can get the meeting room for free, or at a reduced rate, in 2010. Appreciations: Juan wanted to give official appreciation to Greg B. for his efforts in nominating the group for the regional & national award in 2008. Thanks were also given to Steve M. for organizing this year's meeting. USDA Commodity Based Reference Guide-Gary F. (for Richard Zinc who was not able to attend this year due to weather related issues) presented a request to the group to help with a new guide that was being put together to produce a series of fact sheets on new & exotic export pests that would help inspectors when/if they encounter what might be a new exotic pest. They are looking for experts who could provide good images, descriptive text, & be listed as resource people on the publications. Gary showed several slides that listed many of these pests/disease that included: Old World Bollworm, Black Maize Bettle, Silver Y Moth, Rice Cutworm, Andean Potato Tuber Moth, Potato Wart, Potato Smut, Common Rust, & 9 viruses including PVT, PVU, PVV, Tomato Spotted Wilt Virus, Tobacco Ring Spot Virus, Potato Deforming Virus, Tobacco Torrado Virus, Potato Yellowish Virus. Gary will email more on this to the project, including the complete & correct list. 12) Adjourn - Meeting Adjourned at 11:45 AM

*Phil N.-Interactions between PVY & Rhizoctonia. He reported a study in ID during 2007-08 that suggests a link between the incidence of PVY & Rhizoctonia. Fields with high PVY also had high Rhizoc. Data compared PVY levels with yield produced, indicating a 1.5 cwt reduction for each 1% PVY. Fields of low mosaic vs high (>50%) had yields of 411 vs 300 cwt; with US#1 yields of 260 vs 160 cwt Most +PVY plants also had Rhizoc. Plants with & without PVY were dug & the roots were examined for Rhizoc; 81% of the Mosaic plants had Rhizoc while only 12% of the healthy plants had Rhizoc. Was yield reduction due to PVY or Rhizoc? Are PVY infected plants more susceptible to Rhizoc or are Rhizoc infected plants more susceptible to PVY? Q:Did the plants with PVY acquire Rhizoc the previous year & thus the effect was not purely seasonal? i.e. plants with PVY die down early, acquire Rhizoc, & it appears in year 2 A:Maybe, but the previous years field was out of potatoes 8 years so shouldn't have much Rhizoc. More RIGOROUS study may answer these questions. Jonathan W. noted that in his plots, PVY infected plants were more severely eaten by Colorado Potato Beetles than non-infected plants, whether this was because the beetles are attracted to higher sugar levels in the +PVY plants or if the feeding action reduced re-growth rates of the plants was not known. Rob D. noted that there are many cases in CO when a grower challenges a mosaic call, saying its 'just Rhizoctonia', but lab tests confirmed PVY presence. He also pointed out that, under CO conditions, the 1.5 cwt per 1% PVY rule does not hold true, fields with essentially 100% PVY were only yielding about 7-9% less than comparable clean fields, perhaps just a 'Colorado effect'. Phil N. said PVY & PVA vary in regards to being 'current season' or 'tuber perpetuated' with CS infection only reducing yield significantly if they occur early in the season. *Alex K.-PVYo5 in shipments to Mexico. Loads are being rejected at the border for PVYn. Results showed that it was PVYo5 which reacts + in the PVYn ELISA with 1F5 monoclonal Ab, the NAPPO required test for PVYn. Rules need to be changed to allow another antisera or PCR. The original 1F5 came from Peter Ellis & is a monoclonal. Extensive testing using indicator hosts, tuber inoculations, & isozyme analysis, has shown that PVYo5 is a strain of PVYo accounts & does not pose a risk to the Mexican potato industry. Only serology is different (based on a single nucleotide difference). Survey work has shown that PVYo5 is widely spread across the US, and 10-16% of the PVYo detections are PVYo5, perhaps as high as 25% in CO. Alex showed results indicating correct identification by different antisera suggesting NAPPO rules should be changed to allow this new protocol. *Jonathan W./Darrin H.-Tubers Symptoms of PVY in PNW Potato Varieties. Objectives were: (1) See how many PVY+ tubers could be expected with different strains of PVY; (2) See what tuber symptoms are expressed from strains (-ntn, -o, -no, & -n) on various potato varieties (Alturas, Blazer Russ, Premier Russ, Highland Russ, Russ Norkotah, Ranger Russ, Yukon Gold-current season infection). Procedure was: start with clean mini-tubers, inoculate young plants with a spray gun, & evaluate tubers for symptoms at harvest & after storage. Tuber symptoms were often mild at harvest & became more severe when stored. http://www.aphis.usda.gov/plant_health/plant_pest_info/potato/pvy_symptoms.shtml Different PVY strains caused differing symptoms in various varieties, i.e., PVYntn caused no tuber symptoms in A or PR, but other varieties were affected. (see the attachment under minutes for more details). *Jonathan W.-PVY Strain Survey Specialty Grant. Jonathan discussed a new Specialty Grant to monitor PVY strains in seed crops over time. He felt the most efficient way to accomplish this is to have certification agencies submit positive PVY samples in the WGO to him for PVY strain analysis. They don't want tubers/leaves, but feel there is enough virus left on a typical ELISA plate to conduct the analysis, thus the +samples could be circled, plates dried, & sent or samples could be dotted to Nitrocellulose, dried, & sent. To not bias the results, the +PVY samples should be from lots where the initial samples were taken randomly (like in ID), not just conformational samples taken from plants showing mosaic symptoms. They can't use federal funds for matching on this grant so an estimate of time spent by each agency would be used for 'payment in kind' on the grant. Results will be presented by variety. Industry input & direction is critical in obtaining this grant. Jonathan also discussed the need for a national isolation screen program that would compile 'PVY strain' x 'Potato Variety' information (i.e. leaves & tuber susceptibilities/symptom expression under field conditions). Two or three sites could be used. Wisconsin (Amy C.) has already expressed an interest in participating. He also showed promotional literature for 'Classic Russet' repeating an earlier statement that CR is the perfect variety for PVY management because it has good resistance & readily expresses symptoms when infected with PVY. http://www.pvmi.org/Storage/General/Classic Russet Flyer 1 09.pdf *Phillip H.-Screen House Study with PVY Isolates. He reported how various PVY strains react in various cultivars. Foliage & tuber symptoms were observed and they tested for PVX. The screen house environment was as close to field condition as they could get, with 20% shading which most experts said should not affect symptoms expression/virus behavior. Inoculation was via air spray gun on June 26th (same set-up as Jonathan W. used). ELISA testing was done July 9, Aug 1, & Aug 14. PVY strains: o(2), -ntn(2), -n:o(2). Cultivars: Yukon Gem, Yukon Gold, R. Norkotah, Blazer R., Ranger R., R. Burbank, Alturas, Premier R. Tubers were examined for external & internal symptoms. PCR was used to detect PVY strains on tubers. Plants were planted in 4 row blocks with netting around each block to prevent plants from touching. Phil summarized his data. In most cases, the PVY killed the plants by the end of the season. PVYo caused a variety of symptoms from distortion & vein burning in YGe, severe mosaic with no vein burn in BR, to very mild symptoms in YGo & RN. PVYntn gave very different symptom expression in the varieties inoculated, being very mild in YGe but more severe in RR & PR. Data on the % infection by strain & cultivar was shown, strain n:o was the highest, -ntn the lowest, but this varied in each cultivar. The amount of PVY infection by variety was also shown. Overall PR was the lowest, RN the highest. In A, PVYo infection was very low while PVYntn was very high, & one isolate of PVYno was high while the other was low. Yield effects of the virus were also shown & were not comparable to % infection levels, those plants with ntn had higher yields than those infected with PVYo, but this effect varied with variety. The two different PVYn:o strains behaved very differently in the various cultivars. Phil showed slides that compared yield effect on the time PVY gave +reactions in ELISA (the later the +reaction the less the yield effect). Phil N. noted that a longer growing season would likely have increased the differences observed between the strains. He also pointed out that PVY infection always results in a yield loss, but the magnitude depends on when the plant is infected. Tuber symptoms of PVY strains were also followed. Overall the healthy control & PVYo strain had no tuber symptoms. The -ntn strain showed tuber symptoms in most cultivars. Tuber symptoms with the -n:o strain varied between the two different n:o isolates used. Symptoms included arcs, spots, zones, circles, bruise-like areas, & black spots. PCR is the only fast/accurate test available. One important conclusion from the foliage & tuber part was that different strains of PVY react differently in various cultivars. Phil's conclusions: (1) Differing strains effect each cultivar differently & infection level is not proportional to symptom expression; (2) Resistance to PVYo does not mean resistance to other PVY strains; (3) PVY decreased yield, for all strains, in all cultivars, but the magnitude of this effect varied with cultivar & PVY strain; (4) Internal tuber symptoms varied with PVY strain & potato cultivar (See the attachment under minutes for more details). *Mark Paveck-Othello Seed Lot Trials. Data was by variety & included: # of lots by state/province for years 2001-08, & data for lots in the severe category (>10 plants per lot) for PLRV, Mosaic, & Blackleg. The # of total lots have been increasing each year. The highest mosaic levels were observed in RN & Shepody. The highest Blackleg incidence was observed in PR Very little PLRV was observed. Some states had over 40% of lots with severe mosaic, Montana had very few, & Canada none. Mosaic levels overall continued to rise from 2001-08. In 2008, 15% of the lots had severe levels of Mosaic, 4% had severe Blackleg levels, & only 3% had PLRV. *Juan Alvarez-Several Insect Vector Studies. (1) Characterization of the PVY virus receptors in Aphids. PVY has been shown to attach specifically to receptors inside the 5 um of the stylet tip. Previously it was believed that 20 microns were involved or that the virus simply contaminated the stylet. A micrograph showing this attachment site was shown. (2) Looking into the efficacy of insecticides for reducing transmission of PVY. Most insecticides reduce aphid populations, but few reduce virus transmission. Can virus transmission be prevented with insecticides? Rows of potatoes were exposed to viruliforious aphids, sprayed with various insecticides a few days later, then tested by ELISA at several subsequent dates to find out how much virus transmission took place. Insecticides: Provado, Monitor, Movento, Platinum, & Fulfill, alone & in various combinations. They could only use PVYo. Green Peach & Potato Aphids were counted each week after introduction to the plots to compare control. Two applications of insecticides, the 1st at 1 day & the 2nd at 2 weeks after aphid introduction. In summary, Vydate & mineral oil worked poorly in the reduction of virus spread. Some of the others worked fairly well. Mineral oil might have worked better if >2 applications had been used, however phytotoxicity & application cost may have become a problem (in Europe they use at least 6 per season & often combine it with a pyrethroid). The major confounding problem encountered with the treatments was due to the aphids not colonizing the plant block and/or aphids coming off other blocks. (3) The role of Hairy Nightshade in the spread of PLRV & PVY. PLRV infected potato were planted in treatment blocks of: clean HN & PLRV infected HN. The spread in plots of PLRV-HN almost equated the plots with only HN, & both were much greater than the spread in plots without HN or with PLRV infected potato plants. They did the same type of experiment with PVY & HN and found similar results i.e. that HN was a major factor in the spread of PVY within the plots, pointing out the critical nature of controlling HN in potato fields to help control both PLRV & PVY spread. They also studied the efficacy of different aphids in virus transmission on these plots including Green Peach Aphid, Potato Aphid, & Bird Cherry Oat Aphid. They concentrated on the BCOA because aphid traps had shown that at times of the year when they were only trapping 5 GPA & PA, they were trapping 3,000 BCOA, & 300 RGA (tall tube traps that represent a 50 mile radius). Even though transmission efficacy may be lower in BCOA (compared with GPA & PA) it may play a more significant role in virus transmission. In these studies they were finding the GP had 71% transmission efficiency, PA had 29%, & BCOA had 11.5%. Sheer numbers of BCOA thus would outweigh lower transmission efficiencies. For all aphid types, PVY transmission was higher in HN plots than plots without HN. PA showed the highest transmission, perhaps due to greater mobility within the plot (the GPA tended to stay on the original leaves). Juan said this experiment showed him that if you want to find PVY in a potato field, look at the HN. The role of HN in PVY spread should not be underestimated. The seed is viable in the soil for a long time. Aphids can move & transmit virus on up to 4 HN plants before loosing the virus & maintain viruliferous for up to 6 hours after feeding. Winged forms of aphids have the potential to really spread the virus especially if HN is in the picture. They are currently looking into effects of HN volatiles in transmission of PVY. Juan noted that the differences of transmission efficiency indicates there are biological effects on virus-stylet interactions that effect attachment-detachment i.e. it's not just a matter of release upon probing/feeding. It was pointed out that some years you find high levels of spread with low levels of aphids, indicating that aphids must be able to spread to many plants after they acquire the virus. On the other hand, some years there are a lot of aphids present & little spread of the virus, indicating a complex biological interaction far from the original 'dirty needle' transmission theory. Q:(Nina Z.)Could individial aphids be monitored as a means of predicting potential spread. A:No, there can be a lot of un-attached viruses on the stylet, but only the attached virus seems to be important in the transmission. Andy J. pointed out that the same is not true for PLRV where there is a direct correlation between level of virus in the aphid & transmission rates. Juan noted there is also a host effect. When an aphid lands on a plant it doesn't like (and thus only feeds a short while), there is often greater transmission than on plants it likes. It has been demonstrated that the longer an aphid feeds on an infected plant the less likely it is to acquire the virus. Aphids feeding for 1 minute on an infected plant were more likely to transmit the virus to a healthy plant than those that had fed for 2 minutes. Using an insecticide will not reduce the ability of aphids to acquire a virus from infected plants, but will reduce the number of aphids that build up reducing subsequent secondary infield spread. (4)Interactions of Potato Variety Virus Strain on transmission efficiency. A study in which the % infection rates & concentration of virus in the plant was compared between aphid & mechanical transmission. PVY strains: -o,-n:o, & -ntn. Potato varieties: Ranger R., Yukon Gold, Premier R. Effects varied with variety. PR-aphids were unable to transmit PVYo, there was a low transmission using mechanical means. YG-both aphids & mechanical means successfully transmitted the virus (though at different efficiencies, 68% vs 87%). The titer of the virus was much greater with mechanical means. PR-aphids had a low level of infection with PVYn:o, when it occurred there was a very high titer. A discussion of the transmission of these strains followed, including the significance of the differences that transmission & plant titer may have on virus spread. The first is a measure of 'at the time' effect, the latter is an 'after the event' phenomena. Juan emphasized that in regards to effects of this virus on potato varieties (transmission rates & symptom expression) aphid transmission does not equal mechanical transmission. *Revisions were made to the Necrotic Virus Management Plan. Steve Marquerdt lead the discussion on two aspects of the NVMP. (The complete revised text is in the Attachment under minutes)(1) 'Strawman' proposal to revise the current PVY management plan. (2) Revision of the 'Canada/US-Management Plan for Potato Viruses that Cause Tuber Necrosis'. *Alex: They have found a new strain of PVY in ID that typed-out as PVYntn that is not necrotic in tobacco indicator hosts. The difference between this PVY & their 'type strain' was a single nucleotide substitution. This shows just how confusing & complex characterizing the PVY strains can become. Rob D: Why 'all of a sudden' are there so many 'new' strains of PVY? Alex: In the last 10 years or so there have been some shifts in potato varieties grown, resulting in a large change in selection pressures. The increased production of RN & Shepody have raised the pool of inoculum so high that these strains have been able to increase without initial notice. There have been varieties introduced with only partial resistance to PVY; these have increased the selection pressure on PVY to develop new strains (a situation similar to using sub-lethal does of insecticides & insect resistance). It isnt known for sure if the new strains were already here & are just increasing due to selection pressures, or if they are truly new recombinants. Jonathan mentioned he has pictures from the 1940s of the variety 'Chippewa' with what look like PVY induced ring spots. Phil H. thought that in the past some PVY infected tubers might have been misdiagnosed (i.e. one slide showing known PVY tuber symptoms looked like it could have been caused by Fusarium). Alex pointed out that Potyviruses are the most successful virus type in the world & show an amazing ability to evolve into new successful strains. *PLRV is essentially 'out but not quite gone'. Few states are finding PLRV anymore in seed lots. Phil N. pointed out that as PLRV has decreased PVY has increased, could there be a link? Perhaps the increased use of Admire in potato fields is associated, but surely other factors are involved. Is Admire widely used in other crops? Unknown, maybe canola. Alex noted that the new strains of PVY that were emerging in N. America are not new. They have been in Europe for a long time & are just now undergoing selection here. It may be inevitable that we are seeing an increase due to various selection factors. *PMTV-Phil Hamm has been doing work on this virus-fungus complex (with Powdery Scab). PMTV in tubers have been reported from Quebec, parts of the US, & is wide spread in Europe. Symptoms of PMTV in tubers were shown (distinct necrotic arcs). Phil went on to describe the original survey by Canadian scientists that was made on symptomless US processing potatoes (chips) & one seed sample coming into Canada. In this original study PMTV was found in seed from 9 states & in 1 to 33 lots per individual state. Due to the dire political ramifications of these results (i.e. quarantine-wise), this study led to the alarm about PMTV in US seed sources, resulting in PMTV survey of ALL US seed sources. In the US survey, the only +PMTV finds were in Maine. For more information contact Phil. Phil presented slides showing results of a study soil from Powdery Scab where infested fields were tested for PMTV via PCR. The objective of his study was to test Powdery Scab infested soils for PMTV from as many potato-producing areas as possible. This was done by planting tobacco in the soil in the GH, looking for symptoms, & then testing the resulting symptomatic plants for PMTV. Q:(Phil N.)Europe has a problem with PMTV so why the difference? A: Probably climatic differences moderating symptom expression, & possibly variety related. Juan also pointed out that there are different strains of Powdery Scab, some transmit PMTV well & others do not. There may be different PS strains in Europe than the US. Q:(Jeff)Is it possible that some PMTV plants are mistakenly being scored as Alfalfa Mosaic Virus? A:Not likely, PMTV is rather distinct & generally occurs at the bottom of the plant whereas AMV is generally at the top. PMTV does not always occur on stunted plants, as might be inferred by the name of the Virus. Phil said he needs more soil samples in 2009 to continue this work. Samples should be about ½ gal & taken from fields known to have a PS history. He will be contacting everyone. *TRV-Jim C. showed slides showing tuber symptoms of Corky Ring Spot disease which is caused by TRV & vectored by Stubby Root Nematodes. These are found in Potato Progress Vol VIII #1 http://www.potatoes.com/PotatoProgress.cfm in the Research Library section, contact Andy J. for a password. He noted that there are not many requests for TRV testing from his lab, though he suspects that is because the growers know what TRV/CRS looks like & do not need lab confirmation. It certainly is still around in some fields. Q:(Rob D.)Is there any value in fumigating a field as protection against CRS if only low numbers of stubby root nematodes are found? A:(Phil H.)Yes. Phil H. showed a slide of deformed sprout symptoms caused by TRV. Initially they thought it was a herbicide problem, as there were no foliar symptoms of TRV in the fields. He then showed aerial photos from 3 fields in Columbia Basin that demonstrated how devastating this nematode/virus can be, causing poor emergence & large dead areas that can sometimes affect 30% of the field. Q:(Rob. D.)How long does it take from the initial infestation of a field before a grower might observe these type of dead areas. A:(Jim C.)The nematode moves very slowly under normal conditions, so it may easily take 10 years for major field damage to be observed. However, it depends on the rotational crops. Stubby Root N. increases very quickly in corn, so if corn is in the rotation, damage may be observed sooner/more severely. Jim C. noted that often plants with TRV also have Rhizoctonia (or look similar) & he suspects that in the initial stages of a build-up, the TRV infected plants are simply called Rhizoc infections. Q:(Mike T.)Are the poor areas associated with soil type i.e. like sandy ridges? A:(Rob D.)Perhaps. CRS pockets are often associated with sandy ridges in CO. The common denominator of all three fields shown was that they were not treated with Telon II, did not have Vydate in-furrow, & had not used any Temik. In the same season/area fields that had been treated with Vydate were fine, no Vydate = rejection. To View symptoms of TRV in foliage, including the deformed sprouts: http://oregonstate.edu/potatoes/Symptoms%20of%20TRV%20in%20Potato%20-%20Final.pdf. Jim C. pointed out that studies/observations they had done demonstrated that early infection of potato plants with TRV might show some foliage symptoms but did NOT result in tuber symptoms while late season infections resulted in CRS. This is because the virus moves poorly in potato plants (it doesn't need to move easily in the plant because it is spread by soil vectors, not above-ground insect vectors). CRS symptoms are caused when infected nematodes feed on tuber-producing stolons, not when they feed on other parts of the root system. Q:(Rob D.)Why is 'Sprang' such a big problem in Europe & not here, does it have anything to do with the instability of the virus. A:Symptoms are best expressed under cool cloudy conditions, as found in N. Europe, but not so much in US production areas. Phil H. showed a slide that indicated that Telon II, Vydate, & Temik worked well in controlling the nematode, Mocap worked sometimes, & water run metham sodium did not work. Q:How is TRV spread field-to-field? A:(Jim C.)In the Columbia Basin it is already widespread but at very low levels. It is likely the presence of various favored host-weed species in the preceding crop that contribute to it 'just showing up' in a potato field in any particular year. Q:(Rob D.)Does R. Norkotah show CRS symptoms? He asked this because CO has had fields that looked fine for years with no weeds to speak of, then all of a sudden after a RN crop, CRS showed up even though the RN tubers did not have symptoms. Could RN be a 'latent host' for TRV? A:(Jim C.)I do not think RN was a latent host for TRV & that such occurrences after RN were probably just coincidental in nature. He noted that in the last few years there we have experienced warmer drier weather, with more irrigation, & changes in the weed hosts present in fields (nightshade) that have likely contributed to situations where CRS just 'showed up'. *Phytoplasma-Joe M. showed slides & reviewed work done on Beet Leafhopper Transmitted Viroid Agent (BLTVA) that is prevalent in potatoes in the Columbia Basin (aka Purple Top). Trial #1 was a 3-year study of susceptibility of various potato cultivars to BLTVA. Varieties included R. Norkotah, Alturas, Umatilla, R. Burbank, Ranger R., Shepody, FL 1867, & FL 1879 grown in 5 row blocks, & naturally exposed to infected Leaf Hoppers. Symptomatic plants were flagged & later some were sent for confirmation of infection. RN had the highest infection rates, RB & FL 1867 had the lowest. A study was also conducted where caged plants were exposed to infected leafhoppers. At 35 days all varieties showed symptoms of BLTVA except RB which did not develop symptoms for 90 days. Q:(Nick)Were non-symptomatic plants also tested for BLTVA? A:Yes, some were tested (and were negative), but +scores were based on symptoms (only). Q:Could symptomatic plants be caused by some other phytoplasma? A:(Jim C.)In the Columbia Basin they have only found 'Group 6' phytoplasma. Joe said it was possible that some of the symptomatic plants may have been PLRV, but based on testing/experience this was probably less than 1% of the +plants. Trial #2 was a time of infection study that involved sequential exposure of previously caged plants to infected leafhoppers (naturally, i.e. rows of pre-emerged potato plats were caged to prevent exposure to LH & portions of the rows were removed each week). The plants were then examined for Purple Top symptoms. The data presented showed: most infection 10-15 days, little infection at 30-40 days, no infection after 50 days. Joe was not sure if this was due to mature plant resistance or changes in the leafhoppers. In 2009 they plan on introducing +BLTVA leafhoppers into caged plants each week to see if/how the potato plants get infected. That should help answer the question. Phil H. said that RDO felt they were getting infection damage late in the season. Joe said it is possible that plants infected at 53 days just didnt have enough time to show symptoms & would later in the season. Phil also mentioned that in the Hermiston area, growers who were spraying against leafhoppers in late May-early June were protecting their crop from developing Purple Top symptoms. The LH were present all season, but (evidently) were not transmitting BLTVA. Does this mean that BLTVA is not present all season or just that the LH can't effectively transmit it later on? Perhaps it is just a matter of the date symptom expression? Q:(JMc)Where does the original early season BLTVA come from? A:(Joe)Aphids collected off certain over-wintering weeds had lots of BLTVA. The BLTVA is transmitted through the eggs, which are laid on newly emerging potatoes, they then hatch on the potatoes & the nymphs infect the new potato plants. Thus over-wintering weeds in the 'wild areas' around fields are the original source of this phytoplasma. In June, as these areas dry down, the LH leave them & head to other green areas, which happen to be the new potato plants. If the borders were kept green, or a LH-susceptible crop was grown on the edges, this might reduce BLTVA spread to the crop. Soybean borders will not work (as they do for aphids) because leafhoppers dont like soybeans. Phil H. mentioned using Temik treated grass around the potatoes to trap & kill the LH (he does point out this is not a registered use for Temik). Trial #3 involved the study of the translocation of BLTVA from the plants into the tubers. Joe mentioned that the fry data for infected/non-infected tubers were the same. Do infected plants result in infected tubers? If so, how many? The same procedure was used, i.e., allowing potatoes to get naturally infected, flag +symptom plant, test for the presence of BLTVA, harvest +BLTVA plants individually & then test tubers for BLTVA. Results: Most tubers were infected (60-90%) though infection rates varied among varieties. Russet Burbank had the lowest infection rates (25%). Trail #4 involved a grow-out of the infected tubers & observed if they produced symptomatic/+BLTVA plants. Tubers had been stored at 48 F, 700 tubers were observed. Results: 35% of the infected tubers yielded infected plants. Tubers produced were small; in fact so small they would not have been harvested, making this a self-eliminating disease. There were no defects in the tubers produced. Q: Why were so many tubers from infected plants not infected? A: Perhaps it has to do with distribution of BLTVA in the tubers themselves (non-uniform). Jim C. said when they test these tubers they take 2 cores through the center of the tubers, but no work has been done to study the actual distribution of BLTVA in individual tubers. *Other Viruses US Plant Introduction Station-Jorge A. (USDA) in Beltsville, MD gave reported on how potato material is accepted, tested, & released into the US from abroad. The basic process of introduction: acquire material, tissue culture, test for Potato Spindle Tuber viroid (if plus discard), then PCR for Carlavirus, Leutovirus, & Potyvirus. If + they are put into therapy (thermo+virazol), if - run tests DNA for phytoplasma, Ralstonia, & ZC (?& other diseases?), if - release. Time from receipt to release is 3-4 months (if no virus), & additional time if therapy is required (up to 1yr). RT PCR is new to program. They intercepted two potential new viruses in 2008, one a seed-transmitted virus that causes rugosity ('frog-skin'-type symptoms) in potato leaves. Could not mechanically transmit this virus to a new host, could only transmit by grafting. Thus they have added grafting to the screen. The second virus intercepted was an easily mechanically transmitted Nepovirus. It was also seed-borne in true potato seed & had obvious symptoms in tobacco. They have also intercepted a new isolate of PVS from S. America. It had 94% homology with ordinary & Andean PVS strains, giving a strong + in PVS-ELISA, but having no symptoms on indicator host for PVS. Jorge commented that in the Andes where PMTV evolved, the bright yellowing symptoms induced by the virus was a 'sign of a good year'. He related how a local grower was upset that he was roguing the PMTV plants. He explained that the vector (Spongospora subterranea - Powdery Scab) did well in cool rainy seasons & these were the conditions that lead to a good crop! PMTV did not seem to be a concern in that area. Only 5-10% of the tubers from a PMTV infected plants become infected with PMTV. Disease status of selection received: Q:(Rob D.)Are selections received from Europe generally clean? A:Yes, if from Netherlands, Germany, Sweden, & Scotland. No, (PSTV & PVS)if from Poland & some other 'east block' countries. Selections from S. America caused the most problems (except those received from CIP which are normally clean but sometimes have PVS). Selections from Chili often have PVS. Q:(Alex)What type of therapy is used? A:Virazol+heat therapy. They are trying some new chemicals; one is a bacteriostatic chemical that slows down cell-to-cell movement of the virus. Therapy is only used if a virus is found in the initial screen, not routinely. Jorge also noted that they only keep the released lines for about ½ a year after release & then discard them (they dont have resources to keep them much longer). Besides being sent to the requestor, Un-protected varieties are sent to Sturgeon Bay (potato germplasm repository) after release. Variety ID is not part of the program. Recently many transgenic varieties are coming through the facility especially for BASF. McDonalds & Frito-Lay use to request potatoes in the past but not anymore. *Zebra Chip Update - Jim Crosslan gave what will likely be the last Zebra Chip report to the group because this disease is now known to be caused by a bacteria called Liberobacter. (See the attachment under minutes for more info).

Abad, J. A., J.W. Moyer, G.G. Kennedy, G.A. Holmes, and M.A. Cubeta. 2005. An Epidemic of Tomato spotted wilt virus on Potato in Eastern North Carolina. Amer. J. of Potato Res. 82:255-281. Abad, J. A., C. Loschinkohl, and M. Smither. 2008. Detection of an unknown virus in potato seedlings grown from true seed introduced from South America. 2008. Phytopathology 98:S9. Abad, J. A., M. Bandla, R. D. French-Monar, L. W. Liefting, and G. R. G. Clover. 2009. First report of the association of 'Candidatus Liberibacter' species with Zebra Chip (ZC) disease of infected potato plants in the USA. Plant Disease 93:108. Bolotova, Y., Karasev, A.V., and McIntosh, C. Statistical Analysis of the Laboratory Methods Used to Detect Potato Virus Y. Amer. J. Potato Res. 86, 2009 (in press, published on-line). Brown, C.R., H. Mojtahedi, J.M. Crosslin, S. James, B. Charlton, R.G. Novy, S.L. Love, M.I. Vales, and P. Hamm. 2009. Characterization of resistance to corky ringspot disease in potato: a case for resistance to infection by tobacco rattle virus. Am. J. Pot. Res. 86:49-55. Crosslin, J.M. and G. Bester. 2009. First report of Candidatus Liberibacter psyllaurous in zebra chip symptomatic potatoes from California. Plant Dis. (in press). Crosslin, J. M., and J.E. Munyaneza. 2009. Evidence that the zebra chip disease and the putative causal agent can be maintained in potatoes by grafting and in vitro. American Journal of Potato Research (in press). Crosslin, J.M., P.B. Hamm, K.S. Pike, T.M. Mowry, P. Nolte, and H. Hojtahedi. 2008. Management of Diseases caused by Viruses and Virus-like Pathogens. Potato Health Management 2nd Edition. APS Press. Chapter 17 (pages 160-170). Crosslin, J.M., and J.E. Munyaneza. 2008. Phytoplasma diseases of potatoes in the Northwest United States, pp. 128-129. In: S. Chiru, G. Olteanu, C. Aldea, and C. Badarau [eds.], 'Potato for a changing world'. Transilvania University of Brasov Publishing House, Brasov, Romania. Gudmestad, N.C., I. Mallik, J.S. Pasche, and J.M. Crosslin. 2008. First report of Tobacco rattle virus causing corky ringspot in potatoes grown in Minnesota and Wisconsin. Plant Dis. 92:1254. Hu, X., Meacham, T., Ewing, L., Gray, S.M., and Karasev, A.V.. A novel recombinant strain of Potato virus Y suggests a new viral genetic determinant of vein necrosis in tobacco. Virus Res. 2009 (in press). Karasev, A.V., Meacham, T., Hu, X., Whitworth, J., Gray, S.M., Olsen, N., and Nolte, P. Identification of Potato virus Y strains associated with tuber damage during a recent virus outbreak in potato in Idaho. Plant Dis. 92: 1371-1371, 2008. Kirk, W.W., S.L. Gieck, J.M. Crosslin and P.B. Hamm. 2008. The First Report of Corky Ringspot caused by Tobacco Rattle Virus on Potatoes (Solanum tuberosum) in Michigan. Plant Disease 92:485. Lin, H., H. Doddapaneni, J.E. Munyaneza, E.L. Civerolo, V.G. Sengoda, J.L. Buchman, and D.C. Stenger. 2009. Molecular characterization and phylogenetic analysis of 16S rRNA from a new 'Candidatus Liberibacter' strain associated with zebra chip disease of potato (Solanum tuberosum L.) and the potato psyllid (Bactericera cockerelli Sulc). Journal of Plant Pathology 91: 213-217. Munyaneza, J.E., A.S Jensen, P.B. Hamm, and J.E. Upton. 2008. Seasonal occurrence and abundance of beet leafhopper in the potato growing region of Washington and Oregon Columbia Basin and Yakima Valley. American Journal of Potato Research 85: 77-84. Munyaneza, J.E., and J.M. Crosslin. 2008. Zebra chip, a new potato disease in North and Central America, is associated with the potato psyllid, pp. 124-127. In: S. Chiru, G. Olteanu, C. Aldea, and C. Badarau [eds.], 'Potato for a changing world'. Transilvania University of Brasov Publishing House, Brasov, Romania. Munyaneza, J.E., J.L. Buchman, J.E. Upton, J.A. Goolsby, J.M. Crosslin, G. Bester, G.P. Miles, and V.G. Sengoda. 2008. Impact of different potato psyllid populations on zebra chip disease incidence, severity, and potato yield. Subtropical Plant Science 60:27-37. Munyaneza, J.E., V.G. Sengoda, J.M. Crosslin, G. De la Rosa-Lozano, and A. Sanchez. 2009. First report of Candidatus Liberibacter psyllaurous in potato tubers with zebra chip disease in Mexico. Plant Disease (in press). Munyaneza, J.E., J.M. Crosslin, J.E. Upton, and J.L. Buchman. 2009. Incidence of BLTVA phytoplasma in local populations of Circulifer tenellus (Hemiptera: Cicadellidae) in Washington State. Journal of Insect Science (in press). Navarre, D.A., R. Shakya, J. Holden, and J.M. Crosslin. 2009. LC-MS analysis of phenolic compounds in tubers showing zebra chip symptoms. Am. J. Pot. Res. (in press). Nitzan, N., R.A. Boydston,D. Batchelor, J.M. Crosslin, L. Hamlin, and C.R. Brown. 2009. Hairy nightshade is an alternative host of Spongospora subterranea, the potato powdery scab pathogen. Am. J. Pot. Res. (in press). Ottoman, R.J., D.C. Hane, C.R. Brown, S. Yilma, S.R. James, A.R. Mosley, J.M. Crosslin, and M.I. Vales. 2009. Validation and implementation of marker-assisted selection (MAS) for PVY resistance (Ryadg gene) in a tetraploid potato breeding program. Am. J. Pot. Res. http://www.springerlink.com/content/8205108r86227147/fulltext.html DOI 10.1007/s12230-009-9084-0 Srinivasan, R., and J.M. Alvarez, 2008. Hairy nightshade as a potential Potato leafroll virus (Luteoviridae: Polerovirus) inoculum source in Pacific Northwest potato ecosystems. Phytopathology. 98: 985-991. Srinivasan, R., J.M. Alvarez, N. Bosque-Perez, S. Eigenbrode, and.R. Novy. 2008. Effect of an alternate weed host, hairy nightshade, Solanum sarrachoides (Sendtner), on the biology of the two most important Potato leafroll virus (Luteoviridae: Polerovirus) vectors, Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas) (Aphididae: Homoptera). Environmental Entomology. 37: 592-600. Srinivasan, R., and J.M. Alvarez, 2007. Effect of mixed-viral infections (Potato virus Y-Potato leafroll virus) on the biology and preference of vectors, Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae). Journal of Economic Entomology. 100: 646-655. Whitworth, J.L., R.G. Novy, D.G. Hall, J.M. Crosslin, and C.R. Brown. 2009. Characterization of broad spectrum Potato virus Y resistance in a Solanum tuberosum ssp. andigena-derived population and select breeding clones using molecular markers, grafting, and field inoculations. Am. J. Pot. Res. http://www.springerlink.com/content/bl05568j57nk2r18/fulltext.html DOI 10.1007/s12230-009-9082-2