Circular patches of dead grass a few inches to a few feet in diameter appear in the lawn during periods of high humidity and warm temperatures. Dark purplish rings sometimes surround brown areas. Filmy white to tan tufts may cover blades in the early morning if the dew is heavy. After 2 to 3 weeks, the center brown grass may recover and turn green, giving the brown patches a doughnut shape.
Brown patch is one of the most prevalent diseases in warm, humid areas, attacking all types of turfgrass. Lush, tender growth from excessive nitrogen fertilization is the most susceptible to attack. Sometimes only the blades are affected and the grass recovers in 2 to 3 weeks. Keep grass as dry as possible to slow down disease spread. Water only in the morning, one or two times per week.