Brief Summary of Minutes of Annual Meeting

1) Call to order (8:10 AM). Stewart requested copies of hotel receipts for rebate and registration was set at $40. He announced that no Administrative Advisor was present this year (Greg Bohach has left UI). He reminded attendees that a new proposal to renew WERA089 project is needed. It was suggested to set a small committee to help prepare the proposal; this committee will include Jeff McMorran, Stewart Gray, Rob Davidson, and Phil Hamm. 2) Approval of minutes: minutes were approved; however, it was brought to the attendee attention that the committee (Phil N., Phil H., Rob D., Gary F., Alex K., and Steve M.) that was supposed to work on the process of the Outstanding Multidisciplinary Resources Award for 2010 - failed to do so. 3) Introductions. See list of attendees (above). 4) Agenda: approved 5) Stewart Gray briefly discussed the - Schultz Virus Collection - currently being maintained at ARS Beltsville and was in the process of being gotten rid off; the discussion was set to continue the following day. 6) Reports on Seed Certification Washington - Mark Pavek mentioned that PVY levels came down this past season and nothing else unusual had been observed. Rob D. asked whether all the seed lots were tested with ELISA and the answer was no; the inspection was only done visually. Jim Crosslin reported one zebra chip-infected plant found in the WA seed lot trial at Othello; the liberibacter-infected plant was found in only one seed lot that originated from Wyoming. Oregon - Jeff McMorran mentioned that nothing unusual was observed during the season; he however reported that there were some issues with chemicals that had been previously applied for mint in the potato fields. California - Pablo Guzman discussed PVY issues with different potato planting dates. An early (February)-planted seed lot was rejected because of PVY. This happened only in one location and the reasons for the high PVY/aphid levels were unknown. There was also a problem with potato tuber skin cracking (var. White Rose) and a couple of tubers were found with PVY-N. Alex K. does not think it was a PVY issue with that particular field because testing did not really reveal PVY infection. There is a probability that the cracking was due to herbicides. Colorado - Kent Sather reported that potato acreage decreased about 2,000 acres mainly because of rejections of Norkotah (about 1,800 acres) during the summer inspection. No PLRV was seen in CO this year. Post harvest testing was conducted in Yuma, AZ. Plots in Yuma looked good except for Norkotah lots which showed distinctive PVY symptoms. Rob D. reported that there was a lot of rain in cropping areas and a lot of Norkotah were not harvested because of ring rot. He also mentioned that a lot of aphids (all species) were observed because of warm season, leading to very high levels of PVY. Norkotah is not making it to G3. Although a lot of Norkotah are being grown because of high fresh market demand, Norkotah seed production is declining because of PVY. All growers are now required to plant certified seed (PVY tolerance levels: 2% summer inspection, 4% winter grow-out, and 10% at planting). A substantial discussion on state seed PVY related re-certification laws ensued. Idaho - Doug Boze provided a handout summarizing results of winter tests from 2002-2009 and explained that rejection for PVY was reduced in 2009. More Norkotah are being grown but PVY situation has improved. Winter test was conducted in CA and 100% PVY ELISA testing was conducted. Alex K. and Phil N. reported testing samples for PVY strains. Some cultivars were more hard hit than others and none of the lots visited was under 20% infection. However, because of seed shortage of some varieties, the seed was planted anyway. When the plants emerged, no PVY symptoms were apparent, but when testing was conducted, 10-15% more PVY infection was detected, especially in Russet Burbank. Alex and Phil are conducting a survey on PVY necrotic strains in seed lots and mixed infections of PVYo and PVYntn have been observed/detected. The research is being funded by the state and CSREES-SCRI grants. Montana - Nina Zidack reported that a severe frost led to about 15% seed field loss. Very low levels of PVY were observed this year. Rejection of only 2 lots took place. Winter grow-out was conducted in Hawaii, which is a very good location to pick symptoms of PVY. Nebraska - Steve Marquardt reported that the seed acreage is almost staying the same. About 90% of the seed lots passed inspection/certification and the only reason for rejection was PVY. No PVY pressure in commercial production was observed. 7) Research and Extension Reports Alex Karasev - talked about the identification and molecular characterization of the new L26 PVY strain. L26 strain was isolated from potatoes in Idaho and induces typical necrotic NTN symptoms in Yukon Gold tubers. It also induces potato tobacco necrosis (PTNRD). L26 is a recombinant between PVYz and PVYntn and the suggested genetic classification is PVYz/ntn. Phil Hamm - talked about the impact of PVY strains on 8 potato cultivars. Conducted a study in the screenhouse to determine above and belowground symptoms caused by PVYo, PVYntn, and PVYn:o. Varieties tested include Premier, Alturas, Yukon Gem, Ranger, Norkotah, Yukon Gold, Russet Burbank, and Blazer Russet. There was substantial yield loss due to PVY. Yukon Gem showed very low PVY infection in both 2008 and 2009. No or little tuber symptoms in Premier, Burbank, and Blazer. Not all strains of PVY infect plants at the same frequency, produce the same foliage or tuber symptoms, and have the same impact on yield. Alternatively, a same PVY strain may not infect plants at the same frequency, produce the same foliage or tuber symptoms and have the same impact on yield. HOWEVER, PVY REDUCES YIELD. Stewart Gray - talked about the intragenic resistance to PVY. Growers should be concerned with necrosis in tubers and concentrate on those varieties that express tuber necrosis symptoms. Many resistance genes in various plant families encode eIF4E which is a cap-binding protein for viruses. Transformed potatoes using this gene produced PVY resistant lines, with zero infection in these resistant lines. Jonathan Whitworth - talked about a high through-put for post-harvest PVY testing. His Aberdeen lab has developed an RT-PCR testing for all PVY strains. The technique is cheaper compared to currently existing testing methods. A discussion on whether this testing is feasible and practical or can replace the winter grow-out ensued. Phil Nolte - talked about PVY management for seed potato producers. He discussed his recommendations via a newsletter (bulletin) to growers on how to prevent PVY spread. The publication is online and collaborators on the project are Juan Alvarez and Jonathan Whitworth. Alex Karasev - talked about PVY ordinary and necrotic strains in Idaho. He discussed the European historical experience with PVY. He also discussed a US national survey that was conducted in 2004-2006 and focused on late generation seed lots. During that survey, uneven distribution of NTN between states was observed. Almost all necrotic PVY strains were NTN; however, no N was found. In addition, he discussed current PVY monitoring in Idaho. In 2009, Cal White and Norkotah showed no visible symptoms but high levels of PVY were detected after testing. He pointed out that NTN is in Idaho, dominant necrotic strain, and unevenly distributed in the state, with an overall incidence of 21%. PVYo is dominant near Idaho Falls. Incidence of NTN did not increase between 2001 and 2009. Monitoring PVY is necessary. Buy clean seed was his recommendation. Juan Manuel Alvarez talked about hairy nightshade (HNS) as a significant source of inoculum for PVY. He discussed aphids-HNS-virus interactions. HNS produces a lot of seed and is everywhere. This weed is magnet for aphids and they reproduce much better on this host, especially when plants are infected with viruses. Transmission studies conducted between potato and HNS to investigate HNS as source of inoculums were successful. Studies determined PVY concentration 15 and 30 days after planting after inoculation using aphids and both potato and HNS plants. Virus titer was much higher in inoculated leaves and the ones below after 15 days than after 30 days (after germination). He concluded that HNS plays a major role in the epidemiology of PLRV and PVY in the potato ecosystem. Jim Crosslin - reported on his recent partial characterization of an isolate of cherry leaf roll virus transmitted through true seed of Solanum acaule. Potatoes can be infected with this virus but not show symptoms. This virus is probably seed-borne in other host plants. Joe Munyaneza - gave a research update on potato purple top disease. Studies were conducted under screenhouse to accurately determine timing to stop insecticide sprays targeted against the beet leafhopper, insect vector of BLTVA phytoplasma that causes purple top in potatoes. In addition, studies were to determine the relationship between beet leafhopper density and the likelihood of BLTVA transmission and purple top development, with the ultimate goal of developing action thresholds for the beet leafhopper. Preliminary results suggest that younger potato plant growth stages appear more susceptible to BLTVA than older ones. Density as low as 1 beet leafhopper per plant can cause significant BLTVA infection, especially in younger plants. Further studies are needed to establish action thresholds for the beet leafhopper management. Joe Munyaneza - gave a research update on zebra chip potato disease. The disease has been documented in southwestern US, Mexico, Central America, and New Zealand, and is causing losses of millions dollars to the potato industry. The disease is associated with a previously undescribed species of liberibacter transmitted by the potato psyllid. Recent studies conducted in Munyaneza lab showed that the potato psyllid can acquire the bacterium in as a short time as 1 hour and effectively inoculate the bacterium into potato plants in about 2 hours. Preliminary results also indicated that as few as 1 potato psyllid per plant is enough to cause zebra chip, significantly reduce yield and increase reducing sugars. It takes 3 weeks or less for zebra chip symptoms to develop in potato tubers after plants exposure to infective potato psyllids. Moreover, it was demonstrated that, to cause zebra chip, the psyllids have to carry liberibacter; however, liberibacter-free psyllids can significantly affect yield. Low temperatures were shown to slow down liberibacter development whereas extreme temperatures inhibit development of this bacterium. Furthermore, most of, if not, all existing potato cultivars in the Pacific Northwest/US are severely affected by zebra chip. Mark Nakhla - talked about development of PCR-based assays for targeted viruses in foreign germplasm at APHIS-NPGBL. This method uses CANARY Biosensors for rapid detection of regulated plant pathogens, including viruses. B-cells that express pathogen-specific Abs and aequorin are used with this rapid detection technique. Stewart Gray - discussed in details the Schultz Virus Collection in Beltsville. It consists of viruses (about 54 samples) mainly maintained in potato tubers, grown in cages every year and also tested with ELISA on a regular basis. Some tubers however are contaminated with several other viruses. He was trying to find out if anybody would be interested in taking and relocating the collection. A couple of people in the group (including Jim C., Chet S., and maybe Gary F.) were interested in the collection for some uses. There was a suggestion to grow the tubers one more year and then lyophilize them (then keep them that way). The collection moved to Beltsville from Maine. Phil Hamm - briefly discussed powdery scab and mop-top issues. He would like to receive soil samples from other locations/states. He has a permit to import soil samples from most of the states. Jim Crosslin - mentioned a grant awarded by NPC-ARS Potato program to him and Neil Gudmestad (North Dakota State University) to survey tuber necrosis in potatoes. He would like to receive tuber samples with all kinds of necrosis; he has import permit. Stewart Gray - suggested putting together a collection of pictures showing virus symptoms and these pictures could probably be posted online. This picture collection could serve as a diagnostic tool for viruses to the potato producers and researchers. Stewart Gray and Jeff McMorran - discussed the renewal of the WERA089 Project Grant. The renewal must be in 6 months in advance, scope should be broadened to include other 'virus-like' agents and/or diseases vectored by insects (in a virus-like manner), including Zebra Chip/liberibacter. Subcommittee to work on this should include: Jeff McMorran, Stewart Gray, Joe Munyaneza, Nina Zidack, Mark Nakhla, and others. Jeff McMorran - suggested preparation of a 5-10 minute PPT presentation that would convince commercial growers that they should be concerned about the affects of PVY on the yield and quality of their potato crops. It would be mostly a picture based format, using limited amount of tables/graphs. Of preference would be data that visually show data obtained from studies (i.e. two piles of potatoes showing +PVY vs. no PVY, and internal and external defects). Relating how this is a problem that needs to be address on a broad scale (not just farm scale) basis should be emphasized. The thought is to have this presented across the U.S at winter meetings and perhaps at the SPRO meeting this summer. Title might be "Grow Profits, not Problems'. Subcommittee should include: Jon W., Phil H. Rob D. Phil N., Alex P., and maybe others. Stewart Gray - briefly discussed the Memorandum of Understanding (MOU) on PVY in seed potatoes between states and the related Management Plan. 8) Impact Statements Ideas suggested include (1) PVY impacts on yield and quality; (2) Identification reservoirs for PVY; (3) Identification and characterization of a new virus to potatoes - Cherry Leafroll Virus; (4) Continuing work on spread and control of Zebra Chip; (5) Obtaining big grant to study PVY strains in the U.S.; others? Subcommittee to work on this should include: Jeff McMorran, Joe M., Phil Nolte, Dan Hane, Kent S., and maybe others. 9) Election of secretary - Nina Zidack was elected unanimously to become Secretary of the group. 10) Meeting adjourned at 10:55 on March 12.

The identification and molecular characterization of the new L26 PVY strain. L26 strain isolated from potatoes in Idaho. This strain induces typical necrotic NTN symptoms in Yukon Gold tubers and induces potato tobacco necrosis (PTNRD). L26 is a recombinant between PVYz and PVYntn and the suggested genetic classification is PVYz/ntn. Alex Karasev Further documentation of the impact of PVY strains on 8 potato cultivars. Screenhouse studies were used to determine above and belowground symptoms caused by PVYo, PVYntn, and PVYn:o. Varieties tested include Premier, Alturas, Yukon Gem, Ranger, Norkotah, Yukon Gold, Russet Burbank, and Blazer Russet. There was substantial yield loss due to PVY. Yukon Gem showed very low PVY infection in both 2008 and 2009. No or little tuber symptoms in Premier, Burbank, and Blazer. Not all strains of PVY infect plants at the same frequency, produce the same foliage or tuber symptoms, and have the same impact on yield. Alternatively, a same PVY strain may not infect plants at the same frequency, produce the same foliage or tuber symptoms and have the same impact on yield. The over all negative impact of PVY on yield was evident. Phil Hamm The intragenic resistance to PVY was demonstrated showing that growers should be concerned with necrosis in tubers and concentrate on those varieties that express tuber necrosis symptoms. Many resistance genes in various plant families encode eIF4E which is a cap-binding protein for viruses. Transformed potatoes using this gene produced PVY resistant lines, with zero infection in these resistant lines. Stewart Gray A high throughput system for post-harvest PVY testing was developed at the ARS lab in Aberdeen using a RT-PCR testing for all PVY strains. The technique is cheaper compared to currently existing testing methods. A discussion on whether this testing is feasible and practical or can replace the winter grow-out ensued. Jonathan Whitworth PVY management techniques for seed potato producers were developed and made widely available to potato producers and educators via a newsletter (bulletin), Extension publications, and web postings. These recommendations emphasize the means for growers to prevent local and regional spread of PVY. The publication is online and collaborators on the project are Juan Alvarez and Jonathan Whitworth and Phil Nolte. Further information on the presence of ordinary and necrotic strains of PVY in Idaho was summarized as well as the European historical experience with PVY. NTN is in Idaho, was the dominant necrotic strain, and was unevenly distributed in the state. The overall incidence of this virus strain was 21%. PVYo is dominant near Idaho Falls. Incidence of NTN did not increase between 2001 and 2009. In 2004-2006 a US national survey was conducted and focused on late generation seed lots. During that survey, uneven distribution of NTN between states was observed. Almost all necrotic PVY strains were NTN; however, no N was found. PVY monitoring continues in Idaho. In 2009, Cal White and Norkotah showed no visible symptoms but high levels of PVY were detected after testing. Monitoring PVY is necessary. The overall recommendation for controlling this virus is to Buy clean seed. Alex Karasev Further work documentation hairy nightshade (HNS) as a significant source of inoculum for PVY was completed. Aphids-HNS-virus interactions were better charterized. HNS produces a lot of seed and is everywhere. This weed is magnet for aphids and they reproduce much better on this host, especially when plants are infected with viruses. Transmission studies conducted between potato and HNS to investigate HNS as source of inoculums were successful. Studies determined PVY concentration 15 and 30 days after planting after inoculation using aphids and both potato and HNS plants. Virus titer was much higher in inoculated leaves and the ones below after 15 days than after 30 days (after germination). He concluded that HNS plays a major role in the epidemiology of PLRV and PVY in the potato ecosystem. Juan Manuel Alvarez An isolate of Cherry Leaf Roll Virus transmitted through true seed of Solanum acaule was characterized. Potatoes can be infected with this virus but not show symptoms. This virus is probably seed-borne in other host plants. Jim Crosslin Screenhouse studies were used to study pesticide timing effects of control of Potato Purple Top Disease. Studies were conducted to accurately determine timing to stop insecticide sprays targeted against the beet leafhopper, insect vector of BLTVA phytoplasma that causes purple top in potatoes. In addition, studies were used to determine the relationship between beet leafhopper density and the likelihood of BLTVA transmission and purple top development, with the ultimate goal of developing action thresholds for the beet leafhopper. Preliminary results suggest that younger potato plant growth stages appear more susceptible to BLTVA than older ones. Density as low as 1 beet leafhopper per plant can cause significant BLTVA infection, especially in younger plants. Further studies are needed to establish action thresholds for the beet leafhopper management. Joe Munyaneza Current research on Zebra Chip potato disease was summarized. The disease has been documented in southwestern US, Mexico, Central America, and New Zealand, and is causing losses of millions dollars to the potato industry. The disease is associated with a previously undescribed species of liberibacter transmitted by the potato psyllid. Recent studies conducted in Munyaneza lab showed that the potato psyllid could acquire the bacterium in as a short time as 1 hour and effectively inoculate the bacterium into potato plants in about 2 hours. Preliminary results also indicated that as few as 1 potato psyllid per plant is enough to cause zebra chip, significantly reduce yield and increase reducing sugars. It takes 3 weeks or less for zebra chip symptoms to develop in potato tubers after plants exposure to infective potato psyllids. Moreover, it was demonstrated that, to cause zebra chip, the psyllids have to carry liberibacter; however, liberibacter-free psyllids can significantly affect yield. Low temperatures were shown to slow down liberibacter development whereas extreme temperatures inhibit development of this bacterium. Furthermore, most of, if not, all existing potato cultivars in the Pacific Northwest/US are severely affected by zebra chip. Joe Munyaneza A PCR-based assay for targeted viruses in foreign germplasm was developed at APHIS-NPGBL. This method uses CANARY Biosensors for rapid detection of regulated plant pathogens, including viruses. B-cells that express pathogen-specific Abs and aequorin are used with this rapid detection technique. Mark Nakhla Research grants to allow the further study of powdery scab and mop-top (Phil Hamm) and tuber necrosis in potatoes (Jim Crosslin) were received and samples of soil and tubers are needed.

Bolotova, Y., Karasev, A.V., and McIntosh, C. 2009. Statistical analysis of the laboratory methods used to detect Potato virus Y. Amer. J. Potato Res. 86, 265-271. 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 86: 183-187. Crosslin, J.M. 2009. Detection of tobacco rattle virus RNA in processed potato chips displaying symptoms of corky ringspot disease. HortScience 44:1790-1791. Crosslin, J.M., I. Mallik, and N.C. Gudmestad. 2009. First report of Tomato spotted wilt virus causing potato tuber necrosis in Texas. Plant Dis. 93:845. Crosslin, J.M., J.E. Munyaneza, J.K. Brown, and L.W. Liefting. 2010. Potato zebra chip disease: a phytopathological tale. Plant Health Progress doi:10.1094/PHP-2010-0317-01-RV. Crosslin, J.M., K.C. Eastwell, C.M. Davitt, and J.A. Abad. 2010. First report of seed-borne Cherry leaf roll virus in wild potato, Solanum acaule, from South America. Plant Dis. (in press). Crosslin, J.M., P.B. Hamm, W.W. Kirk, and R.W. Hammond. 2010. Complete genomic sequence of a tobacco rattle virus isolate from Michigan-grown potatoes. Arch. Virol. 155:621-625. Gharalari, A.H., C. Nansen, D.S. Lawson, J. Gilley, J.E. Munyaneza, and K. Vaughn. 2009. Knockdown mortality, repellency and residual effects of insecticides for control of adult Bactericera cockerelli (Homoptera: Psyllidae). Journal of Economic Entomology 102: 1032-1038. Hu, X., Karasev, A.V., Brown, C.J., and Lorenzen, J.H. 2009. Sequence characteristics of Potato virus Y recombinants. J. Gen. Virol. 90, 3033-3041. Hu, X., Meacham, T., Ewing, L., Gray, S.M., and Karasev, A.V. 2009. A novel recombinant strain of Potato virus Y suggests a new viral genetic determinant of vein necrosis in tobacco. Virus Res. 143, 68-76. Karasev, A.V., Nikolaeva, O.V., Hu, X., Sielaff, Z., Whitworth, J., Lorenzen, J.H., and Gray, S.M. 2010. Serological properties of ordinary and necrotic isolates of Potato virus Y: a case study of PVYN misidentification. Amer. J. Potato Res. 87, 1-9. 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. Lin, Y-H., K.L. Druffel, J. Whitworth, M.J. Pavek, and H.R. Pappu. 2009. Molecular characterization of two Potato Virus S isolates from late blight resistant genotypes of potato (Solanum tuberosum). Arch Virol 154:18611863. Miles, G.P., J.L. Buchman, and J.E. Munyaneza. 2009. Impact of Zebra Chip Disease on the Mineral Content of Potato Tubers. American Journal of Potato Research 86:481-489. Miles, G.P., M.A. Samuel, J. Chen, E.L. Civerolo, and J.E. Munyaneza. 2010. Evidence that cell death is associated with zebra chip disease in potato tubers. American Journal of Potato Research (in press). Munyaneza, J.E., J.M. Crosslin, and J.L. Buchman. 2009. Seasonal occurrence and abundance of the potato psyllid, Bactericera cockerelli, in south central Washington. Am. J. Pot. Res. 86:513-518. Munyaneza, J.E., J.M. Crosslin, and J.L. Buchman. 2009. Susceptibility of different potato cultivars to purple top disease. Am J. Pot. Res. 86:499-503. Munyaneza, J.E., J.M. Crosslin, J.E. Upton, and J.L. Buchman. 2010. Incidence of the beet leafhopper-transmitted virescence agent phytoplasma in local populations of the beet leafhopper, Circulifer tenellus, in Washington State. J. Insect Sci. 10:1-10. Munyaneza, J.E., J.M. Crosslin, J.L. Buchman, and V.G. Sengoda. 2010. Susceptibility of different potato plant growth stages to purple top disease. Am. J. Pot. Res. 87:60-66. Munyaneza, J.E., T.W. Fisher, V.G. Sengoda, S.F. Garczynski, A. Nissinen, and A. Lemmetty. 2009. First report of Candidatus Liberibacter Solanacearum associated with psyllid-affected carrots in Europe. Plant Disease 94: 639. 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 93: 552. Munyaneza, J.E., V.G. Sengoda, J.M. Crosslin, J. Garzon-Tiznado, and O. Cardenas-Valenzuela. 2009. First Report of 'Candidatus Liberibacter solanacearum' in Tomato Plants in Mexico. Plant Disease 93: 1076. Munyaneza, J.E., V.G. Sengoda, J.M. Crosslin, J. Garzon-Tiznado, and O. Cardenas-Valenzuela. 2009. First Report of 'Candidatus Liberibacter solanacearum' in Pepper in Mexico. Plant Disease 93: 1076. Nolte, P, JM. Alvarez and JL Whitworth. 2009. Potato Virus Y Management for the Seed Potato Producer. University of Idaho CIS #1165. Available online at: http://info.ag.uidaho.edu/catalog Pantoja, A., A.M. Hagerty, S.Y. Emmert, and J.E. Munyaneza. 2009. Leafhoppers (Homoptera: Cicadellidae) associated with potatoes in Alaska: species composition, seasonal abundance, and potential phytoplasma vectors. American Journal of Potato Research 86: 68-75. Riga, E., R. Larsen, K. Eastwell, N. Guerra, L. Guerra, and J.M. Crosslin. 2009. Rapid detection of Tobacco rattle tobravirus in viruliferous Paratrichodorus allius from greenhouse and field specimens. J. Nematology 41:60-63. Sengoda, V.G., J.E. Munyaneza, J.M. Crosslin, J.E. Buchman, and H.R. Pappu. 2010. Phenotypic and etiological differences between psyllid yellows and zebra chip diseases of potatoes. Am. J. Pot. Res. 87:41-49.