Alternaria solani, fungus; foliar = early blight or target spot
Infection:
Tubers get infected by early blight only be direct contact with spores during harvest (lifting). Early blight will spread in storage.
Symptoms:
The skin surface has brownish-black, circular or oblong patches that are slightly sunken. The patches are well demarcated by a raised margin separating it from healthy skin. Cutting through a lesion (patch or spot), a shallow, dry, brown rot will appear. The rot is sharply delineated from healthy tissue by a corky margin. In advanced stages, it can become watery and the tuber shrivels up. Secondary infections are not a factor as with late blight.Early Blight stages in tuber
Control Practices:
Control foliar development of early blight. Harvest after complete vine kill and allow for skin set. Keeping tubers cool will halt decay and keeping them aerated will inhibit spread in storage
Tuber Blemishes