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.
Gallery Images: C. Grau