Southern Corn Leaf Blight (Bipolaris maydis)
Southern Corn Leaf Blight is a disease caused by the pathogenic fungus Bipolaris maydis. This was a minor disease of corn for many years, with no economic effect on yield. In 1970, a highly virulent strain called Race T appeared on corn hybrids with Texas male sterile cytoplasm. Losses were severe.
Symptoms of Race lesions are spindle-shaped with yellow-green halos. They will later have dark, reddish-brown borders and occur on leaves, stalks, leaf sheaths, husks, and shanks. Cob Rot ear occurs as well as ear drop. The fungus overwinters in corn debris and on seed. Wind and splashing water spread the spores rapidly in the field under ideal conditions, cycling in about 72 hours. Control with resistant hybrids.