Southern corn leaf blight of corn
Southern corn leaf blight is caused by the fungus Bipolaris maydis. There are two races of the pathogen. Race O normally attacks only leaves. Lesions are tan, somewhat rectangular in shape, and have reddish-brown margins. Race T attacks leaves, husks, stalks, leaf sheaths, shanks, ears, and cobs. Race T lesions are rectangular to elliptical (¼ to ½ inch wide by ¼ to ¾ inch long) with a reddish-brown border that may be surrounded by a chlorotic zone. Stalk and leaf infections initially appear as purple spots that develop tan-gray centers. Ear infections result in a gray-black lesion on the husk that extends into the kernels, appearing as a black felt-like mold. Seedlings from infected kernels are often blighted.
Resistant hybrids and inbreds are available. Foliar fungicides labeled for southern corn leaf blight are available. Southern corn leaf blight lesions. Image: C. Grau
Ear mold from southern corn leaf blight. Image: C. Grau