Cochliobolus victoriae

Cochliobolus victoriae is an ascomycete fungus in the family Pleosporaceae that causes Victoria blight, a disease of oats marked by stem weakening, seedling death, leaf damage, basal necrosis, foliar striping, blackened nodes, root rot and premature ripening of seed. The fungus produces a toxin called victorin, which harms only oat plants carrying the LOV1 gene, the same gene that gives Victoria oat varieties their resistance to crown rust. Because Victoria oats were widely planted across the United States in the 1940s for that crown rust resistance, Victoria blight, first recorded in 1946, reached epidemic proportions by 1947 and 1948, forcing growers to abandon Victoria oat varieties entirely and, with them, their crown rust protection.