Nigrospora Rot

a disease of corncobs and cotton bolls caused by the Fungi Imperfecti Nigrospora oryzae, N. spaerica (causative agents of Nigrospora cob rot), and N. gossypii (causative agent of Nigrospora rot of cotton bolls). The disease is characterized by the formation of black spots—the sporebearers of the fungus—on affected organs. Severely infected cobs are underdeveloped and underweight and split open vertically together with the stalk. At the bases of the caryopses and in the tissues of the stalk, especially in the lower parts, there are numerous black clusters of spores forming black dots or streaks. The seeds of affected cobs have decreased germinating capacity, get very moldy during sprouting, and yield weak shoots that often die before emerging to the soil surface. In cotton bolls affected by the disease, all or some of the lobules do not completely open. The affected fiber is black-olive in color and does not fluff out. Control measures for Nigrospora rot are the same as for other fungal infections of plants.