Brown patch (Rhizoctonia solani)
What does it look like?
Brown patch is a common summertime disease that has almost circular patches ranging from 3 inches to several feet in diameter. Symptoms include leaf tip browning and leaf lesions. In turf cut below 1 inch, the outer edge of the brown patch may develop a bluish ring called the smoke ring. The smoke ring is not apparent in higher-cut lawns.
When is a lawn susceptible?
The much-hated brown patch forms in the summer, when humidity is high and temperatures climb over 85°F. If the temperature and the humidity add up to more than 150°F, you have brown patch conditions, so it's time to go on the defensive. Take care not to over-water or over-fertilize. Although all grasses can get brown patch, Tall fescue and Perennial ryegrass lawns are the most susceptible. Warm-season grasses, such as St. Augustine and Bermuda grass, invite brown patch in the spring or fall.
How can we get rid of it?
Make sure you do not over-fertilize or over-water. Water early in the morning - this will help keep wetness down, and avoid late-evening watering, especially on nights when the temperature doesn't drop below 65°F. With warm-season grasses, avoid heavy fertilization in the fall. Fungicides can help stop brown patch severity, but the real key is not to stimulate growth during those high-risk conditions. Remember and respect the 150°F rule!
