Black Dot (E3181)
This Michigan Potato Diseases publication offers timely advice on identification and management. Black dot disease control and symptoms.
Black dot is a common disease of potato. It is most often observed on tubers but it can affect all parts of the plant. The disease has probably been underestimated in the recent past as the symptoms are similar to more common potato diseases. On potato foliage symptoms are nearly indistinguishable from early blight and on tubers it produces blemishes that are easily mistaken for silver scurf. Although not as serious as other more common potato diseases such as black scurf, silver scurf, or common scab, it can be more devastating as it affects all parts of the plant. Above ground it can infect the vascular system causing wilt, and below ground it can cause severe rotting of roots, shoots and stolons, leading to early plant decline, discolored tubers and reduced yields.