Brown patch is a fungal disease that develops during the hot, humid conditions of summer, transforming a green lawn into one with circular brown patches a few inches to several feet in diameter. Infected grass turns a dark purplish-green before fading to light brown, and has a sunken or flattened appearance. You may still see some healthy, unaffected grass within a diseased area.
Gray Leaf Spot (GLS) is a fungal disease that affects various turfgrasses. Lesions start as olive green to brown, water-soaked dots, no larger than a pinhead. As the infection progresses, the lesions become larger and ash-colored with purple to brown margins. The turf appears scorched and thin as if suffering from drought.