Development of Comprehensive Strategies to Manage Potato Virus Y in Potato and Eradicate the Tuber Necrotic Variants Recently Introduced Into the United States
Potato Virus Y (PVY) has re-emerged as a serious disease problem in many seed potato production areas in the United States. In the past, PVY has been managed effectively by potato seed certification programs, but the widespread acceptance of cultivars that are tolerant of infection (plants are diseased, but do not show symptoms) and the emergence of necrotic strains of PVY bring new challenges to seed certification, seed trade and potato production. Many of these necrotic viruses induce mild foliar symptoms in potato and are more difficult to identify during field inspections, yet they are more damaging to tubers. The current practices in potato seed certification which are dependent upon visual assessment of virus infection levels in the growing crop cannot effectively manage the new strains of PVY in the current array of cultivars, and they will not prevent the necrotic strains from becoming prevalent. Inaccurate field inspections and improper diagnosis have contributed to increased incidence of some necrotic strains leading to some unnecessary trade restrictions. Necrotic strains of PVY pose a significant threat to the potato industry due to reductions in yield and lower tuber quality. Additionally, because they are regulated pathogens, the necrotic strains will continue to impact interstate and international seed trade. An evolving national management plan sanctioned by the industry provides guidelines that will be refined by our research to reduce overall PVY incidence and limit the introduction of necrotic strains. Several of the principal investigators of this project have served as the scientific advisors for the plan development and revision. The US-Canada Management Plan for Viruses that Cause Tuber Necrosis in Potato Tubers, signed into effect in April 2006, is designed to facilitate the trade of potatoes within and between the US and Canada while protecting the potato industry from several emerging viruses, including PVY, that cause yield and quality losses in the potato crop. Management strategies and research needs of the industry are listed in the plan and by design are reviewed and refined by the industry on an annual basis. The overall objective of this project is to refine the current management strategies based on industry needs to reduce overall levels of PVY and prevent the spread of necrotic strains. Specifically, we will 1) Work with seed certification agencies to develop new tools to better identify and eliminate PVY from seed stocks. These will include training aids to better identify infected plants in the field, and improve diagnostics and post harvest testing procedures to better evaluate the tuber crop, 2) Work with breeders to develop PVY resistant cultivars or cultivars with recognizable symptoms. Current cultivars and breeding lines will be evaluated in regional trials to look for new sources of resistance and to identify the level of susceptibility to a range of PVY strains, 3) Work with growers to develop cost effective, on-farm virus control strategies that are aimed at reducing the amount of PVY introduced to the crop and controlling the spread of the virus in the crop.