Septoria Leaf Blotch

any one of a group of plant diseases caused by fungi of the genus Septoria and characterized by the formation, mainly on the leaves, of small, mostly rounded spots, which are dark at the periphery and light, sometimes almost white, in the center. Infected grain crops are distinguished by elongate blotches.

The most common and harmful are Septoria leaf blotch of grain crops (causative agents Septoria graminum, S. nodorum, and other species), tomato (S. lycopersici), and currants and gooseberries (S. ribis). Septoria leaf blotch also attacks millet (S. panici-miliacei), hemp (S. cannabis), soybeans (S. glycines), grapes (S. ampelina), and many other plants. The majority of the causative agents are preserved on plant remains. Distribution of spores and infection of plants occur in damp weather, when the pycnidia swell. With severe infection, the leaves and shoots become dry, and the stems turn brown, wrinkle, and often bend over. Premature leaf fall, necrosis of husks, and underdevelopment of grain (in cereals) are also observed.

Control measures include destroying plant remains, using crop rotation when cultivating annual crops, spraying plants with fungicides, growing resistant or less susceptible varieties, and applying a complete mineral fertilizer.