Corn Crops and Diseases

Southern corn leaf blight- caused by the fungus Bipolaris maydis (Helminthosporium maydis) occurs worldwide, but is particularly damaging in regions of warm, moist weather. Lesions on the leaves caused by Race 0 of the fungus are elongated between the veins, tan, up to one inch long, with limited parallel margins and buff to brown borders. Lesions produced by Race T (which was very prevalent in the early 1970s) are tan, 1/4 to 1/2 inch x 1/4 to 1 inch, spindle-shaped or elliptical, with yellow-green or chlorotic halos. Later, the Race T lesions often have dark, reddish-brown borders and may occur on all parts of the plants. Race T is commonly found only when hybrids with Texas male sterile cytoplasm are grown. Both races of the fungus overwinter on corn debris in the field. Thus, rotation and destruction of residue will reduce losses due to this disease. Resistant hybrids are also available.