Brown Patch is a fungal disease that presents a serious threat each spring and fall because of the onset of cooler temperatures, wet grass and overcast conditions.
Conditions most favorable for brown patch development include (1) the presence of active fungi, (2) vigorous growth of a susceptible grass, (3) daytime temperatures ranging between 75 and 85, (4) the presence of free moisture on the foliage, and (5) night temperatures falling below 68.
Brown Patch Symptoms
On warm season turf grasses, the disease is characterized by at least two different types of symptoms. The most common is a circular pattern of brown grass with a yellowish ring (smoke ring) of wilted grass on the perimeter of the diseased area. The leaves can be easily pulled from the stolons with the smoke ring because the fungus destroys the tissue at the base of the leaf. Symptoms first appear as small circular patches of water-soaked, dark grass that soon wilt and turn light brown. Stolons often remain green as the disease develops, the circular patches enlarge, smoke-rings become apparent and new green leaves may emerge in the center of the circular areas.
Controlling Brown Patch Diseases
When environmental conditions are favorable, brown patch is likely to develop on susceptible turf grasses. The severity of the disease can be somewhat controlled by following a strict fertilization schedule that only apply the proper amount of nitrogen and trace elements during the ideal times; by watering early in the morning to remove dew and all the grass to dry quickly; mow grass a little taller with a sharp mower blade, and when possible, by bagging the lawn clippings during likely periods of disease activity. Fungicide applications are most effective when used as a preventative before the disease has become established in the lawn.