Several factors can cause brown spots on your lawn. Compare yours to these photos to determine the cause and solution for your turf's trouble.
Also called cottony blight, can appear to come out of nowhere during hot, humid weather. It can be identified by a telltale slimy or greasy water-soaked lawn and the presence of patches that are less than 6 inches in diameter. To help prevent pythium blight, avoid mowing moist grass, don't cut too short, water only in the morning and apply a balanced fertilizer (not a high-nitrogen product). Check the soil's pH and maintain a level in the neutral to slightly acidic range.
Brown patch is a disease of rye, tall fescue, fine fescue and Kentucky bluegrass turfs. Symptoms include brown patches that range between six and 20 inches in diameter that may have a purplish-gray smoke ring border or frog-eye pattern with green grass in the center. This can be exacerbated by overuse of nitrogen fertilizer. Preventive measures include aerating the lawn, watering deeply and infrequently (versus a daily light sprinkling) and ensuring proper drainage.
Dollar spot manifests as silver-dollar sized straw-colored spots on a freshly mowed lawn (the shape will appear more irregular on longer grass). Telltale signs include a white fungus that resembles a cobwebs early in the morning when dew is present, and straw-colored lesions with reddish-brown borders on grass blades. To help prevent dollar spot, don't mow grass too short; keep it at three to four inches, and never mow more than one-third its length in one mowing. Water only early in the day and don't over fertilize.
Households with canine family members, especially female ones, often have brown spots all over their grass, caused by the ammonia content in urine.
Leaf spot presents as reddish-purple spots on leaves that create a gradual browning and thinning appearance in the lawn. As spots grow bigger, their color fades to light brown or beige, sometimes surrounded with a dark border. To help prevent leaf spot, follow best mowing and watering practices and avoid overfertilizing.