BIOLOGICAL & ECONOMIC IMPACTS OF EMERGING POTATO TUBER NECROTIC VIRUSES & THE DEVELOPMENT OF COMPREHENSIVE & SUSTAINABLE MGMNT PRACTICES.

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: NEW
• Funding Source: OTHER GRANTS
• Reporting Frequency: Annual
• Accession No.: 1004958
• Grant No.: 2014-51181-22373
• Project No.: NYC-149555
• Proposal No.: 2014-07878
• Program Code: SCRI
• Project Start Date: Sep 1, 2014
• Project End Date: Aug 31, 2015
• Grant Year: 2015

Project Director
De Jong, W.

Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853

Performing Department
Plant Breeding & Genetics

Non Technical Summary
The US potato industry is under threat from newly emerged potato viruses that render potatoes unmarketable. Our overall goal is to reduce the impact of these tuber necrotic viruses by working with all sectors of the potato industry to develop and implement new practices leading to a healthier potato crop and higher farm income. Virologists and plant pathologists will develop improved diagnostic methods to rapidly determine the type of virus and amount of disease on a farm. Technologies will be transferred to growers and seed inspectors so they can better make appropriate disease management decisions. Host plant resistance to virus disease is the best management option, but few virus resistant potato varieties exist. Virologists and potato breeders will work in concert to develop molecular markers to shave years and considerable cost off the development and release of new virus resistant potatoes. Until virus resistant potatoes are developed, potato growers need short term options to better manage virus disease on the farm. Entomologists, vector biologists, plant pathologists, and horticulturists will work to better understand the factors contributing to the spread of viruses onto and within a farm, and how the viruses impact tuber quality and processing traits during harvest and storage. This information will lead to regionally appropriate disease management strategies, as well as reduce the amount of virus in the crop and its impact on tuber quality. Economists will conduct a cost-benefit analyses of existing seed regulations, as well as possible new regulations suggested by scientists, to help the potato industry decide whether changes in farm practices, seed certification programs, and national and state regulations are worthwhile.

Animal Health Component

50%

Research Effort Categories

Basic

40%

Applied

50%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	1310	1081	30%
212	1310	1101	40%
212	1310	1130	20%
212	1310	1170	10%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants;

Subject Of Investigation
1310 - Potato;

Field Of Science
1170 - Epidemiology; 1130 - Entomology and acarology; 1101 - Virology; 1081 - Breeding;

Keywords

potato

potato mop-top virus

potato virus y

resistance

tobacco rattle virus

tuber necrotic virus

Goals / Objectives
Viruses are the major disease problem affecting the seed potato industry. Failure to adequately control viruses decreases the amount of certified seed available and creates downstream hardship for commercial growers. Shortage of certified seed regionally encourages movement of seed potatoes and their associated viruses across regions, and has contributed to the recent emergence of tuber necrotic viruses in all seed and commercial production regions. Tuber defects resulting from tuber necrotic viruses have expanded the significance of virus disease from strictly a seed issue, to a quality issue impacting all sectors of the industry. Our overall goal is to reduce the impact of tuber necrotic viruses to manageable levels by engaging all sectors of the potato industry to modifying existing practices. A cost-benefit analyses of scientific recommendations will be conducted when appropriate to assist industry and regulatory agencies in deciding acceptability of proposed changes to farm practices, certification programs, and national and state regulations. The three major goals are:1. Assist seed certification agencies to amend current practices and improve their ability to detect, monitor and regulate virus in seed stocks. Specifically we will study or develop:a. Diagnostics for virus identification in foliar and tuber tissue, and vector populations from soil.b. Scientifically and economically feasible alternatives to the current post-harvest field grow-out.c. Inspector training for field detection of PVY, PMTV and TRV and apps for data collection.2. Assist breeding programs to develop improved methods to identify and characterize useful virus resistance. Specifically we will study or develop:a. Expression of tuber necrosis induced by PVY, PMTV and TRVb. Genetic markers for resistance to virus infection/replication and tuber symptom development.3. Assist growers with cost effective risk assessment tools to manage virus impacts on the farm. Specifically we will study or develop:a. Risk and economic analyses of virus incidence in seed potatob. Risk models for aphid management and timing of harvest to minimize disease.c. Impact of virus and timing of infection on tuber value at harvest and out of storage.

Project Methods
Basic science methods will be employed to better understand the geographic and genetic diversity and evolution of tuber necrotic virus populations and their vector populations. These data are critical to the development of improved diagnostic methods that can be evaluated in a variety of locations and conditions, and by different levels of technical expertise. Technologies will be transferred during formal laboratory and field exercises and through on-line training modules. This will help to ensure that any new methods are likely to be implemented and will lead to improved decision making.Reactions of potato varieties to the various virus and vector populations will be evaluated at multiple locations in different environments to better understand the biotic and abiotic factors influencing the impact of viruses on plant health and tuber quality, and will better define levels and mechanisms of plant resistance or defense against virus disease. A better understanding of the spectrum of potato plant reactions to the various tuber necrotic viruses will facilitate the selection and development of potato breeding populations best suited for the discovery and characterization of molecular markers useful for rapid selection of virus resistant potato clones. Usefulness of any markers will be evaluated in multiple breeding programs associated with the project. Robust markers and protocols will be distributed to other breeding programs via the website and meeting presentations.Controlled and replicated field and greenhouse experiments using selected potato varieties representing all market classes and all virus strains and species will generate data on virus impacts on tuber quality and yield. Harvested tubers stored under different conditions will be used to evaluate virus impacts on processing and end-use parameters. Many of these characteristics will be evaluated in collaboration with the processing industry so the benefits of the research can directly impact the consumer of potato products.Field studies and publically available agricultural databases will provide information on spatial and temporal aspects of virus vector populations, cropping and landscape use and diversity, and virus incidence. All of these data will be used to build predictive models to refine regional best management practices that growers can employ to reduce the effects of virus disease on the potato crop. Validation of models will occur in different locations and useful information will be transferred to growers via grower conferences, on-line resources and other outreach activities.

Progress 09/01/14 to 08/31/15

Outputs
Target Audience:Target audiences for the project include seed certification and regulatory agencies that work to maintain high seed potato quality, the potato farmers, processors and consumers they serve, as well as the scientific community. Changes/Problems:Although we were notified the grant was awarded on September 12, 2014, funds were not released to Cornell University until March 4, 2015. Most of the Subcontracts were in place by April 20, 2015. NIFA allows grantees to back charge expenses to the start of the grant (September 1, 2014), but most universities only allow accounting transfers up to 90 days prior to the start of the subaccount. Accordingly, much of the year 1 budget expenses started in January or later. Additionally, hiring of personnel was not allowed until accounts were in place. Despite the lack of funding and dedicated project personnel during the first 7-8 months of the grant, progress was made and preparations for the 2015 potato production season were completed. However, the timeline a number of project objectives was shifted into the second term. What opportunities for training and professional development has the project provided?Four post-doctoral associates, 3 graduate students and 4 undergraduate students were actively engaged in pursuing the goals of this project, furthering their training and experience in virology, vector biology, entomology and plant breeding. How have the results been disseminated to communities of interest?The results of this project have disseminated to the potato industry, including seed certification and regulatory agencies, and potato growers and processors, through presentations at conferences, trade shows, webinars, websites and workshops, as well as via personal consultation with project staff. The results have reached the scientific community largely through publications and presentations at professional conferences. What do you plan to do during the next reporting period to accomplish the goals?1. Assist seed certification agencies to amend current practices and improve their ability to detect, monitor and regulate virus in seed stocks. Specifically we will study or develop: 1.a. Diagnostics for virus identification in foliar and tuber tissue, and vector populations from soil. Pictures of foliar and tuber symptoms for each of the major PVY strains on widely grown potato cultivars will be posted on a redesigned project website (www.potatovirus.com). The multiplex RT-PCR protocol (developed in the Hamm lab at OSU) that detects six major potato viruses will be validated using tubers from several different potato cultivars. A second year of spectral measurement data will be collected at the PHT in Hawaii and in fields in WI. Additional PMTV and TRV isolates collected from multiple sites across the U.S. will be characterized and sequenced to better understand the genetic diversity of these viruses. Efforts will continue to quantify the soil borne vectors of PMTV and TRV from soil samples. 1.b. Scientifically and economically feasible alternatives to the current post-harvest field grow-out. Experiments in year 2 will focus on optimizing the use of existing RT-PCR protocols for diagnosing virus infection in dormant tubers and comparing results with those obtained by current protocols. 1.c. Inspector training for field detection of PVY, PMTV and TRV and apps for data collection. A two day school is planned for June 2016 at Othello, WA to train seed certification inspectors, growers, and other interested parties in the visual identification of virus infected potatoes and in the laboratory analysis of foliar and tuber samples. 2. Assist breeding programs to develop improved methods to identify and characterize useful virus resistance. Specifically we will study or develop: 2.a. Expression of tuber necrosis induced by PVY, PMTV and TRV Experiments to evaluate PMTV and TRV resistance/susceptibility in widely grown NA cultivars will be repeated in year 2. Evaluations of NA cultivars for PVY-induced tuber necrosis resistance/susceptibility will continue. 2.b. Genetic markers for resistance to virus infection/replication and tuber symptom development. Research described for Year 1 activities will continue. Additional crosses may be necessary to obtain populations that are segregating for the traits to be mapped. 3. Assist growers with cost effective risk assessment tools to manage virus impacts on the farm. Specifically we will study or develop: 3.a. Risk and economic analyses of virus incidence in seed potato Additional data to be collected from participating seed certification programs to validate and refine the model Dr. McIntosh is developing. 3.b. Risk models for aphid management and timing of harvest to minimize disease. 2015 data will be compiled and analyzed in models that identify risk factors in the landscape that contribute to aphid vector abundance, timing of flights, and spread of PVY. During the 2016 production season additional aphid and virus data will be collected in ME, WA, OR and ID. 3.c. Impact of virus and timing of infection on tuber value at harvest and out of storage. Virus-infected (PVY, PMTV and TRV) tubers collected from the various field trials grown in 2015 will be evaluated for internal and external symptom expression (at harvest and during storage) as well as for quality and processing attributes.

Impacts
What was accomplished under these goals? Goal 1. Assist seed certification agencies to amend current practices and improve their ability to detect, monitor and regulate virus in seed stocks. To help seed certification programs better identify virus-infected plants during inspections, plant samples from winter grow-out test plots in Hawaii and Florida were collected in January and analyzed to detect and characterize the PVY strains prevalent in seed production areas. The ordinary strain of PVY (PVYO) continues to decline in prevalence relative to the recombinant and tuber necrotic strains, PVYNWi, NO, NTN. As a result, modifications and improvements were made to a PCR-based diagnostic assay to better detect and differentiate PVY strains. Efforts continue to document the foliar symptoms that each of the different PVY strains and strain variants induce on widely grown potato cultivars. To help get information to growers and regulatory programs more quickly, without needing to wait for a grow-out of tubers, a multiplex RT-PCR protocol was developed. This new method can accurately and simultaneously detect six important potato viruses -alfalfa mosaic virus,potato leaf roll virus,potato mop top virus,potato virus Y,tobacco rattle virus, tomato spotted wilt virus - in a single sample. This assay has been optimized to detect viruses in dormant tubers but also works with foliar samples. To determine if it is possible to differentiate potato varieties based on how leaves reflect light, foliar spectral measurements were collected in January from over 700 samples in Hawaii. Initial findings suggest that it is possible to accurately classify varieties using foliar reflectance, but reveal that it is important to fully characterize the spectral range within a variety. Variety identifications were best accomplished using healthy plants. Preliminary analyses found that leaf reflectance could correctly identify virus-infected plants with a mean accuracy of 73%. PMTV isolates from around the U.S. were sent to Washington State University to characterize genetic diversity. To date, the sequence of a WA isolate of PMTV indicated it was closely related to virus isolates from northern Europe. We'd like to understand whether PMTV and TRV issues parallel that with PVY, i.e., are there a wide diversity of virus types that require different strategies for detection and management, or are PMTV and TRV essentially homogeneous across the U.S.? A quantitative real-time PCR assay is being developed to determine population densities of the TRV vector, stubby root nematodes, in soil. Preliminary experiments looked at nematode species composition and relative numbers from soil samples collected in ND. A total of eight groups of plant-parasitic nematodes were detected; six of these contained stubby root nematodes. At the location where variety resistance trials will be conducted, stubby root nematode density averaged 23 nematodes/kg of soil. This will be compared with levels at harvest to quantify resistance levels of varieties to stubby root nematodes. A duplex RT-PCR assay was developed to quantify levels of the fungal vector of PMTV,Spongospora subterranea(Ss). The standard curve implemented with this assay will facilitate and permit normalization of Ss across soil samples. A major thrust of this project is to develop methods and diagnostic tools that allow direct testing on dormant tubers. Preliminary experiments looked at the effects of taking cores from tubers before they were shipped to the post-harvest test site in Hawaii.None of the cored tubers developed rot and tubers cored immediately before gassing (to break dormancy) had higher emergence than uncored tubers. The benefit of coring was reduced if the tubers were allowed to suberize. Coring also enhanced the stem number and overall vigor of the potatoes. Goal 2. Assist breeding programs to develop improved methods to identify and characterize useful virus resistance. Greenhouse experiments are continuing in NY and ID to evaluate susceptibility of important North American potato cultivars to tuber necrosis caused by PVY. Field plots were established in WI, OR and WA to evaluate response to three common strains of PVY. The focus is on a limited number of cultivars important in those regions; fry processing cultivars in OR, specialty varieties in WA, and chip and tablestock clones in WI. A field site for testing varietal reactions to PMTV was established in ND. This is on a private farm that has had issues with PMTV and powdery scab for several years. Two field sites, in ND and WA, were established to test reaction to TRV. At both locations and at the PMTV location in ND, replicated plots of 68 potato cultivars were established. Foliar symptom expression will be recorded weekly and tubers will be harvested and evaluated for symptom expression and also checked for the presence of virus to determine relative susceptibility/resistance scores. Two markers were developed for a PVY resistance gene originating from a wild species, Solanum chacoense. Plants are now being grown for a few additional crosses to validate the PCR-based markers. Two populations (Waneta x Pike, Pike x Superior) were evaluated in NY to develop genetic markers linked to potato tuber necrotic ringspot disease (PTNRD) expression. Tuber disease expression segregated in the Waneta x Pike population and true seed was sent to Michigan State University to establish a mapping population. This population will be phenotyped and genotyped in 2015 to identify genetic markers for PTNRD. A cross between Russet Norkotah and Yukon Gold was made to develop a population for mapping several PVY strain-specific resistance genes. A small number of genotypes from this population will be tested in 2015 and if they segregate for resistance, true seed will be sent to Michigan State University (MSU) to develop and genotype a mapping population. Breeding clones derived from potato cultivars Kiva and Teena appear, based on two years of field screening, to be resistant to PMTV and have been planted in Aberdeen, ID to be evaluated for agronomic characteristics. Crosses of PMTV and TRV- resistant breeding clones with the susceptible cultivar Alturas have also been made. A small number of genotypes from each population will be tested in 2015 and if they segregate for resistance, true seed will be sent to MSU for genotyping. Goal 3. Assist growers with cost effective risk assessment tools to manage virus impacts on farm. A preliminary economic model was developed that balances the costs and benefits of allowable virus levels in seed and assumes a competitive market. The model accounts for potato yields and the costs of growing suitable seed potatoes, both of which are affected by the maximum allowable virus levels for certified seed. Changes in virus tolerance limits are influenced by the price of potatoes, the relationship between potato yields and standards, and the fraction of seed potatoes that meet the certification standard. Refinement of the model continues as additional data is gathered from seed certification agencies. Aphid flight and species composition data was obtained for the central U.S. (WI, MI, MN, ND) for 2005-14, from ME for 2010-2012, and from CO for 2010-2014. These data are being used to develop models that predict risk periods for virus transmission. The USDA provides yearly maps that show the spatial arrangement of all agricultural fields in any area of the U.S. Coupling this with virus incidence data from seed certification agencies and the aphid data above is being used to develop and test models that predict virus incidence at the end of the season in potato seed fields. Plots have been planted to provide virus-infected tubers of several important processing (chip and fry) varieties for storage and quality trials, to determine if PVY, PMTV and/or TRV infection has a significant impact on tubers quality during storage and/or affects quality of the final products.

Publications

• Type: Other Status: Published Year Published: 2015 Citation: Alyokhin, A. 2015. Preventing the Spread of Potato Viruses: What Insecticides Can and Cannot Do. Webinar presented for the Pest Management Network, available at http://www.plantmanagementnetwork.org/edcenter/seminars/potato/PotatoViruses/
• Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: Cating, R. A., C.N. Funke, N. Kaur, P.B. Hamm, and K.E. Frost, 2015. A multiplex reverse transcription (RT) high-fidelity PCR protocol for the simultaneous detection of six viruses that cause potato tuber necrosis. American Journal of Potato Research 92: In press.
• Type: Other Status: Published Year Published: 2015 Citation: Dwyer, J. D. 2015. When is the Best Time to Initiate PVY/Aphid Management Strategies. Spudlines, Volume 50 (3).
• Type: Other Status: Published Year Published: 2015 Citation: Dwyer, J. D. 2015. Aphid Populations in 2014. Spudlines, Volume 50 Number 3.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: Fulladolsa, A. C., F. M. Navarro, R. Kota, K. Severson, J. P. Palta, and A. O. Charkowski. 2015. Application of marker assisted selection for Potato virus Y resistance in the University of Wisconsin Potato Breeding Program. American Journal of Potato Research. In press.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Groves, R.L., Frost. K.E. and Huseth, A.S. 2014. Integrating grower-driven and publically held data for improved plant protection. Phytopathology 104:S3. pp.159.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Mallik, I. and Gudmestad, N.C. 2015. First report of Potato Mop Top virus causing potato tuber necrosis in Colorado and New Mexico. Plant Dis. 99:164.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Plaisance, A. and Yan, G. P. (2015). Comparison of two nematode extraction techniques. 54th Annual Meeting of the Society of Nematologists, East Lansing, MI, July 19-24. (Abstract)
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Ramesh, S.V., G. Raikhy, C.R. Brown, J.L. Whitworth, and H.R. Pappu. 2015. Complete genomic characterization of Potato mop top virus from the United States. Archives of Virology DOI 10.1007/s00705-014-2214-0.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Weber, B. N., R. A. Witherell, and A. O. Charkowski. 2015. Low-cost potato tissue culture with microwave and bleach media preparation and sterilization. American Journal of Potato Research 92:128-137.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Yan, G. P. and Gudmestad, N.C. (2015). Stubby root nematode as the virus vector of corky ringspot disease of potato. 54th Annual Meeting of the Society of Nematologists, East Lansing, MI, July 19-24. (Abstract)
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Yan, G. P., Plaisance, A., and Ye, W. (2015). Plant-parasitic nematodes on field crops in Southeastern and Northeastern North Dakota. American Phytopathological Society Annual Meeting, Pasadena, CA, August 1-5. (Abstract)
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Alyokhin, A. 2014. Compatibility issues in chemical control of aphids on potato. 2014 Potato Pest Management Conference, Presque Isle, ME.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Alyokhin, A. 2015. Potato Virus Y management: Challenges and options. 30th Annual Maine Potato Conference, Caribou, ME.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Alyokhin, A., R. Groves, S.I. Rondon, E. Wenninger, A. Murphy, A. Buzza, S. Mondal, and R. Cating. 2015. Landscape effects on the epidemiology of Potato Virus Y. Potato Expo, Orlando, Florida.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Chikh-Ali, M. and Karasev, A.V. Genetic diversity of Potato virus Y strains circulating in potato crops in Saudi Arabia and in Indonesia, Annual Meeting of the Idaho Association of Plant Protection, November 5, 2014, Jerome, ID
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Dwyer, J. D. 2014. Aphid Populations in 2014: Management Strategies. 2014 Potato Pest Management Conference, Presque Isle, ME.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Dwyer, J. D. 2015. Potato Pest Management, Agricultural Trade Show. Augusta, Maine.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Dwyer, J. D. 2015. Aphid Flights and Control Strategies. 30th Annual Maine Potato Conference, Caribou, ME.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Funke, C. and Karasev, A.V. Changes in PVY strains circulating in potato in the PNW, and reactions of potato cultivars to different strains of PVY, WERA-89 Potato Virus Research Meeting, March 4, 2015, San Diego, CA
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Gray, S.M. 2014. Potato Virus Y (PVY): A rapidly changing problem for the seed and commercial potato industries. Annual meeting of the Korean and Japanese Plant Pathology Societies, Busan, S. Korea.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Gray, S.M. 2015. Biological and Economic Impacts of Emerging Potato Necrotic Viruses and The Development of Comprehensive and Sustainable Management Practices. Washington/Oregon Potato Conference, Kennewick, WA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Gray, S.M. 2015. Potato Virus Y (PVY): A rapidly changing problem for the seed and commercial potato industries. Maine Potato Growers.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Groves, R.L., 2014. Frito Lay North America, Seed Seminar, Aphid Modeling: and Management of Potato virus Y. February 18, FLNA Headquarters, Plano, TX.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Groves, R.L., E.J. Duerr, A.O. Charkowski, A.B. Crockford, and A.S. Huseth.ESA Section Symposium, 2014. Effects of Cropping System Landscapes on the Ecology and Management of Insect Vectors and Transmitted Pathogens, Influence of regional landscapes on Potato virus Y incidence in seed potato. ESA Annual Meeting, Portland, OR, November 18, 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Inglis, D.A. Jan 29, 2015. Impacts of Potato virus Y on the quality of specialty potato tubers. Washington/Oregon Potato Conference, Kennewick, WA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Inglis, D.A. Feb 27, 2015. Potato pathology research projects in 2014. Western Washington Potato Workshop, Mount Vernon, WA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Inglis, D.A. Mar 4, 2015 Special seminar on Potato virus Y in western Washington. WSU Graduate Students, Mount Vernon, WA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Inglis, D.A. Mar 6, 2015. Potato virus Y and the quality of specialty potato tubers. Narrated presentation delivered electronically to Klamath Falls Potato Growers.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Karasev, A.V. PVY strains in Idaho seed supply and new sources of resistance, Idaho Seed Potato Growers Seminar, January 20, 2015, Pocatello, ID
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Karasev, A.V. Changes in PVY strains circulating in potato in the PNW, and reactions of potato cultivars to different strains of PVY, Washington and Oregon Potato Conference, January 29, 2015, Kennewick, WA
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Karasev, A.V. Resistance to Potato virus Y in potato and classification of PVY strains, Department of Plant Pathology, University of Helsinki, March 2, 2015, Helsinki, Finland.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Karasev, A.V. Strain-specific resistance against PVY in potato. J.R. Simplot Company, Plant Sciences Division, March 25, 2015, Boise, ID
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Karasev, A.V. and Kuhl, J.C. Changes in PVY Strain Composition & New sources of PVY Resistance for Potatoes, Idaho Potato Conference, January 22, 2015, Pocatello, ID.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Rondon, S. PNW updates and PVY information continuously provided online at Potato Update http://oregonstate.edu/dept/hermiston/trap-reports.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Wenninger, E.J. and S. Mondal. Contribution of non-colonizing aphids to PVY incidence in potato in Southern Idaho. Montana Potato Conference, Missoula, MT, 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Wenninger, E.J., S. Mondal, and D. Shrestha. Interactions of PVY with its aphid vectors. Potato Virus WERA meeting, San Diego, CA, 2015.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Wenninger, E.J., S. Mondal, and D. Shrestha. Interactions of PVY with its aphid vectors. Idaho Seed Potato Growers Seminar, Pocatello, ID, 2015.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Whitworth, J. and Karasev, A.V. Mop Top, Tobacco Rattle & Other Tuber Necrotic Viruses, Idaho Potato Conference, January 21, 2015, Pocatello, ID.