Potato virus Y: an evolving concern for potato crops in the United States and Canada

Authors: Gray, Stewart; DE BOER, SOLKE - Canadian Food Inspection Agency; LORENZEN, JAMES - University Of Idaho; KARASEV, ALEXANDER - University Of Idaho; Whitworth, Jonathan; NOLTE, PHILLIP - University Of Idaho; SINGH, RUDRA - Agriculture And Agri-Food Canada; BOUCHER, ALAIN - Canadian Food Inspection Agency; XU, HUIMIN - Canadian Food Inspection Agency

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2010
Publication Date: 12/1/2010
Citation: Gray, S.M., De Boer, S., Lorenzen, J., Karasev, A., Whitworth, J.L., Nolte, P., Singh, R., Boucher, A., Xu, H. 2010. Potato virus Y: an evolving concern for potato crops in the United States and Canada. Plant Disease. 94:1384-1397.

Interpretive Summary: This feature article chronicles the past and present problems that Potato virus Y (PVY) presents for the North American potato industries and provides potential solutions for its management in the future. PVY is the number one disease problem for the seed potato industry and the most important virus disease affecting potato. PVY was successfully managed for many decades by seed certification practices, but the introduction of new strains of the virus, the release of several popular asymptomatic cultivars, and an increase in late season disease spread have all reduced the effectiveness of visual inspections of the potato crop during the growing season as a means of weeding out those fields that have high virus infection. New strains of the virus that cause mild foliar symptoms are responsible for inducing necrosis in tubers that is not detected until after harvest; these reduce not only yield, but quality. Furthermore some of these are quarantined pathogens and affect trade with existing and potential partners. Mild foliar symptoms due to virus strain or cultivar response leads to increased numbers of infected plants remaining in the field and producing infected tubers that are planted the following year. This cycle has resulted in increased disease levels that cannot be managed by seed certification alone. Successful management of PVY in the future will require an integrated approach of seed certification, on-farm disease control and the integration of virus resistance into new cultivars.

Technical Abstract: Potato virus Y (PVY) is the type member of the Potyviridae and the most economically important disease problem in seed potatoes in many areas of the world. The virus is responsible for decreases in yield and quality, but the main issue in seed potato production is a requirement for strict virus tolerance limits for certified seed. High levels of PVY have been responsible for many seed lots being rejected as certified seed resulting in a significant reduction in crop value, and at times in a shortage of certified seed. Compounding the problem is an emergence of new strains of the virus in North America. This feature article chronicles the history of PVY in the U.S. and Canadian potato industry, including the development and implementation of management plans primarily focused on maintaining unrestricted trade. The results of a comprehensive three-year survey of seed potato crops revealed that although the ordinary strain, PVYO, still predominates in most production areas, strains that cause necrosis in tobacco and potato tubers, e.g. PVY, PVYNTN, PVYN-Wi, are becoming prevalent across the U.S. and Canada. PVYO causes a severe mosaic, necrosis, and/or stunting in potato; symptoms that facilitate successful PVYO management by seed certification programs using visual inspections. The necrotic strains are mild in many potato cultivars and not easily recognized in visual inspections. Successful management of PVY in seed potatoes in the coming years will necessitate a more comprehensive strategy of seed certification, on-farm disease control and the integration of virus resistance into new cultivars.