Bulletin #2492, Potato Facts: Potato Diseases Caused by PVY and PLRV (PDF) By Steven B. Johnson, Ph.D., Extension Crops Specialist For information about UMaine Extension programs and resources, visit extension.umaine.edu. Find more of our publications and books at extension.umaine.edu/publications/. Potato diseases caused by viruses can cause losses in potatoes in the form of decreased yields,