Theres two sorts of blight though.
Theres Late Tuber Blight, which rots the potatoes, and is a fungal spore caused by Phytophthora infestans,
Early blight, caused by the fungus Alternaria solani, is a disease that is most severe on maturing or under-fertilized potato vines. The disease actually occurs late in the season, often first appearing in late July (bingo).
Symptoms usually develop first on the older leaflets of mature plants, spreading to the younger leaves under favorable weather conditions. This disease occurs over a wider range of climatic conditions than late blight.
Early blight may also more rarely infect tubers.The lesions appear on the surface of tubers as dark, sunken, irregularly shaped areas. The lesions are often surrounded by a raised violet border. The fungus will invade the tuber, causing shallow, dark, necrotic, hollowed out areas in the tuber that can be traced to surface lesions.
