Ryegrasses and tall fescue are most susceptible, but Brown Patch also attacks Kentucky bluegrass and fine fescues.
Look for 6- to 20-inch diameter brown patches, sometimes with a purplish-gray "smoke ring" border or a "frogeye" with green grass in the center. Leaves show tan lesions with brown edges.
Prevention includes reducing thatch, proper watering to keep leaves dry, providing good drainage, and choosing resistant varieties. Excessive nitrogen applications can increase the occurrence and severity of brown patch.