Helminthosporium Leaf Blight of Maize

Southern corn leaf blight is caused by the fungus Cochliobolus heterostrophus and includes races O, T, and C, which possess specific virulence toward plants with certain types of cytoplasmic male sterility. Symptoms manifest as small spindle-shaped lesions up to 4 cm long, necrosis of leaf tissue, ear rot, and blackening of seeds.

Northern corn leaf blight, caused by Exserohilum turcicum, is characterized by the appearance of large lesions up to 20 cm long with a grayish center and a dark conidial coating. The disease primarily affects leaves, rarely involving leaf sheaths and ears. Cultivar resistance is provided by specific genes Ht1, Ht2, Ht3, and HtN, the interaction of which with physiological races of the pathogen determines the nature of the infection development.