Gray Leaf Spot

Gray leaf spot causes severe damage primarily on St. Augustinegrass lawns, but occasionally may also be found infecting bermudagrass and centipedegrass lawns.

The first signs are small brown spots on the leaves, but these spots will grow rapidly into large, elongate, tan to gray spots, surrounded by brown/purple borders. A yellowish “halo” may surround some of the spots, or an overall leaf yellowing may occur.

During warm, humid weather, the gray leaf spot will produce a gray cottony growth on the dying leaves. When conditions are favorable for the disease, large areas of turf may appear to be scorched similar to signs of drought stress.

There are many ways to help reduce the risk of gray leaf spot development. Reduce the thatch layer (if excessive), irrigate deeply and infrequently, avoid high nitrogen fertilizer levels, avoid stresses induced by herbicides and other pests, and by mowing the lawn at the proper height (if disease is present, only mow when the grass is dry).