Oregon State University researchers say they've found two fields in their region harboring thousands of volunteer potato plants infected with the Liberibacter bacterium that causes the crop disease zebra chip.
The fields, located in Southern Washington near Hermiston, Ore., and now planted in corn, were all hard hit by zebra chip last season.
Phil Hamm, director of OSU's Hermiston Agricultural Research and Extension Center, said the testing confirms volunteers could provide a source of the bacteria for potato psyllids - cicada-like insects that spread the disease.