AgronomyThis Ain’t Your Grandfather’s PVY

This Ain’t Your Grandfather’s PVY

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Potato virus Y (PVY) remains one of the biggest threats in potato production today. Tackling it requires a fresh approach — and industry buy in.

A combination of cutting-edge tools — like advanced diagnostics, innovative breeding, and integrated pest management — offers hope for managing the impact of PVY and ensuring the long-term health of potato crops.

Jonathan Whitworth presented on the latest strategies for tackling PVY, one of the biggest threats in potato production today.

USDA Agricultural Research Service (ARS) plant pathologist Dr. Jonathan Whitworth took center stage at the Potato Growers of Alberta annual conference last November, discussing the shifting landscape of PVY management.

With more than 20 years’ experience at ARS, nine years as a senior editor of the American Journal of Potato Research, and his now holding the position of president of the Potato Association of America, Whitworth is a respected leader in potato research.

His work focuses on evaluating how PVY strains affect different potato varieties, developing tools for early detection, and contributing to breeding programs that introduce virus resistance. He also studies how various cultural practices can support integrated management of this pest. By emphasizing the importance of understanding PVY’s diversity and transmission, Whitworth is helping to shape the strategies farmers need to stay ahead of this evolving challenge.

Spud Smart caught up with Whitworth after his presentation to walk through some of the industry’s most pressing PVY questions.

Spud Smart (SS): This Isn’t Your Grandfather’s PVY,” addresses PVY, one of the most challenging diseases in potato production due to its rapid evolution. While all diseases evolve, what makes PVY such a particular challenge?

Jonathan Whitworth (JW): PVY is a challenge because there is a symptom by variety interaction that didn’t used to exist in North America prior to the early 2000s. Back then there was essentially only PVYO and just a few varieties like Russet Burbank. These varieties had typical mosaic symptoms, easily seen and rogued by seed growers. As varieties with mild to very latent symptom express were used, such as Norkotah and Shepody, we also had the emergence of necrotic or PVYN type strains. These new strains produce milder mosaic symptoms, making it difficult for seed growers to lower PVY even with diligent rogueing.

SS: How far have we come in managing PVY … and what’s ahead?

JW: Great strides have been made in the combined use of mineral oil and insecticides by seed growers to reduce PVY. The best line of defense is PVY resistant varieties. These varieties have a resistance gene called Ry. A variety with this gene it is essentially immune to all currently known strains of PVY. These are conventionally bred varieties and are available as russet, red, and chip type. These varieties are not yet widely grown with a few exceptions like ‘Eva’, a round white that was number seven in seed acres in 2019. One of these genes has been cloned and can be put into existing varieties using molecular techniques. Industry acceptance of this approach is still pending.

SS: Your work focuses on two critical pieces of PVY mitigation: IPM and breeding for resistance. What advice would you give to farmers about PVY-mitigating cultural practices?

JW: No one technique will provide the solution. For seed growers, isolation of fields, use of mineral oil and insecticides and removal of visible PVY will help. For commercial growers, purchasing seed with low percentage PVY will help reduce yield loss. That information should always be checked on a winter test or grow out report. For all growers, sometimes we focus on the exact percent of PVY listing in a grow-out report and due to sample size and statistical confidence levels it is really an indicator of PVY amount. We really should think of low, medium, and high when looking at a grow-out report.

SS: Should all farmers be using PVY-mitigating IPM all the time?

JW: Yes, because in a system where you can’t make your neighbours’ decisions on seed sources and where they plant, it is best for all to follow practices to reduce PVY in the whole system. The aphids that move PVY around don’t follow property lines.

SS: What’s coming down the pipe for resistant cultivars?

JW: Look to see more Ry resistant varieties being released. Currently there are about four russet varieties, five round white/chip type varieties, and five red/specialty type varieties, all with an Ry gene incorporated through conventional breeding. A new breeding line A12305-2adg with Ryadg gene will soon be released. It is a medium to late maturing russet that has met the industry specifications in the National Fry Process Trial.

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