Scab is strictly an appearance problem and does not affect potato quality. Early blight is caused by a fungus and characterized by circular, brown to black lesions on the leaves. Lesion shape may change form circular to angular if a large leaf vein stops the fungi progression. Early blight lesions have a bulls eye appearance. Lesions usually appear on the lower leaves first and may then progress upwards on the plant until all of the foliage is affected and the plant dies prematurely.
Stressed plants are more susceptible to early blight than health plants.
Maintaining proper soil fertility and good water management will help prevent early blight. Early maturing varieties are more susceptible to early blight than later maturing varieties. If a fungicide application becomes necessary, consult your local Extension agent. Pink rot , often called water rot, is characterized by swollen, waterlogged tubers that may be partially or totally rotted. A fungus causes the flesh of these rotted tubers to turn pink within a half hour or so after they are cut.