Foliar damage occurs especially after rainfall followed by a dry period. Tuber infections can be largely avoided by defoliation before harvest.
Early blight [Alternaria solani]
Early blight - image 1
Pattern of damage
Small, rapidly growing dark brown spots with concentric rings develop on the leaves. The diseased tissue is sharply delineated from the surrounding healthy tissue (Picture 1). The lower leaves are infected first. So-called dry rot, also called hard rot, is found on the tubers.