A potato virus, around for years, is mutating. Growers have grown used to seeing some signs of Potato Virus Y, or PVY, in fields. The disease causes foliar damage and infected plants must be taken out of certified seed fields, but otherwise the virus hasn't really been a threat. That could be changing.
Researchers are finding new strains of the virus damaging tubers with little apparent injury to an infected plant's leaves. When specialists in the U.S. surveyed PVY strains between 2004 and 2006, they found 70 percent were the ordinary PVY that causes leaf damage but not tuber damage.
By 2010, surveys showed tuber necrotic strains are increasing in both incidence and distribution, said Stewart Gray, Agricultural Research Service New York. Tuber necrotic strains accounted for 18 percent, up from 6 percent previously, and ordinary strains had fallen to 53 percent. "This is no longer just a seed certification problem. The problem now affects all aspects of potato production," he said.
Original news release