Individual plants may produce few potatoes even though large vines develop during the season. The potatoes that are produced develop a firm brown rot at the stem end. Seldom is the entire root affected. Controls recommended for black rot and scurf will also control this disease. If foot rot is recognized to be a serious problem, then early harvest will aid in reducing losses.
Foliar symptoms vary from purple ring spots to vein-clearing.
Symptoms become masked as leaves grow older. The most characteristic symptom is seen within potatoes since no visible surface symptoms are evident. Slicing a potato lengthwise will reveal brownish to black corky areas inside. If seed potatoes are stored at 60oF., development of the corky areas does not proceed. However, if seed are stored at 70 degrees F., severe corkiness develops.