by Enrico Villamaino

A researcher from the University of Wisconsin is working in conjunction with academics in Oregon and a collective of agricultural professionals to reduce the rate of viral infection in seed potatoes.

“Seed Potato Production and Breeding in Organic Systems,” a webinar hosted by Oregon State University’s Department of Horticulture, was moderated by Rue Genger, a researcher in the University of Wisconsin-Madison’s Department of Horticulture. According to Genger, “Many potato diseases can be passed to the next generation in seed potatoes. Pathogen accumulation reduces seed potato vigor. This is called ‘running out,’ and it can eventually result in crop failure.”

Potato Virus Y (PVY) is the most common cause for seed potato failure. In order to combat infection of potato plantings from viruses like PVY, Genger outlined a three-step process. It incorporates starting with a disease-free planting stock, limiting field generations and regular field, harvest and post-harvest inspections and testing.

In order to ensure a disease-free planting stock, healthy tissue samples from potatoes are grown in greenhouse pots or hydroponics to produce culture plantlets called “minitubers.” These minitubers are then used to seed a new planting. The minitubers’ cultivation and maintenance in a sterile environment is a major step in eliminating contaminated tissue.

Limiting field generations, also known as using a “flush-through system,” refers to the practice of regularly using new seed potatoes from a certified disease-free planting stock. This can reduce the danger of a disease being passed on in a recycled planting from one generation to the next, with the disease growing in strength each time. Genger recommended that the replanting of seed potatoes in the field not exceed five to seven years.

Finally, regular testing throughout the growing process, even after harvesting, is essential. “Virus infection can occur at every stage of the plants’ life cycle,” Genger explained. “Often the infection can occur very late in the growing season, when symptoms are less likely to express themselves in the leaves. A post-harvest inspection can catch infections that may have been undetectable earlier.”

Genger noted that following these procedures can help growers become certified seed potato producers. Certified seed potato certifications are currently available in California, Colorado, Idaho, Maine, Michigan, Minnesota, Montana, Nebraska, Nevada, New York, North Dakota, Utah, Washington, Wisconsin and Wyoming.