The symptoms of brown patch vary according to mowing height. In landscape situations, where mowing height is greater than 1”, brown patch appears as roughly circular patches that are brown, tan, or yellow in color and range from 6” to several feet in diameter. The affected leaves typically remain upright, and lesions are evident on the leaves that are tan in color and irregular in shape with a dark brown border. When the leaves are wet or humidity is high, small amounts of gray cottony growth, called mycelium, may be seen growing amongst affected leaves. In close-cut turfgrasses (1” or less), brown patch develops in roughly circular patches, ranging from a few inches to several feet in diameter, that are brown or orange in color. Distinct foliar lesions are not visible and mycelium is typically not present, but a black or dark gray ring, called a smoke ring, may surround the brown patches. The smoke ring is evidence of active disease development and is only present when the turfgrass leaves are wet or humidity is near 100%.
For more information visit North Carolina State's turf files