Plants under stress are susceptible to black dot. Black dot readily attacks plants whose petiole N and P levels are 4,000 to 5,000 ppm below recommended levels. It invades plants weakened by other diseases and often is found in association with these diseases. Tuber infection is usually superficial, resembling silver scurf, but it can become significant in seed stock and during storage. Tuber discoloration has been noted on chipping types in Colorado and on french fries in Idaho.
Black dot can cause greater shrinkage of infected tubers in storage than non-infected ones.
Storing at a relative humidity below 90 percent will increase loss. Use certified seed, since seed is the only way known to infest a clean field. There are no resistant potato cultivars. Thin-skinned cultivars are more susceptible. Do not sterilize seed pieces.