Turcicum leaf blight is caused by the fungi Exserohilum turcicum. It is a major constraint to corn production in many growing regions worldwide with a growing season characterized by high humidity and moderate temperatures (17 to 27°C). Yield losses as high as 70% have been attributed to Turcicum leaf blight. Symptoms of Turcicum leaf blight are oval, water-soaked spots on leaves. Mature symptoms of Turcicum leaf blight are characteristic cigar shaped lesions that are 3 to 15cm long. Lesions are elliptical and tan in color, developing distinct dark areas as they mature that are associated with fungal sporulation. Lesions typically first appear on lower leaves, spreading to upper leaves and the ear sheaths as the crop matures. Under severe infection, lesions may coalesce, blighting the entire leaf.