As the disease progresse s, affected leaves turn yellow and senescent and either dry up or fall off . Tuber infection occurs less frequently than leaf infection and are usually evident only after several months of storage. Tuber lesions are dark, sunken, irregularly shaped and often surrounded by a raised violet border. . The underlying flesh is dry, leathery, and usually brown. . In advanced decay, the tissue is often water-soaked and yellow to greenish yellow.
Lesions can enlarge during storage, and tubers can become shriveled in advanced cases.
Early blight tuber lesions are not as prone to invasion by secondary organisms as compared to other tuber rots. The multicellular conidia vary in color from pale to light tan and are usually formed singly. They are detached easily and are carried by air currents. Colonies are spreading and gray-brown to black. In routine work the identification of the pathogen is assisted by leaf symptoms, host range, and the cultural characteristics of the fungus.