Brown Patch This disease is prevalent during moist, hot weather on over-fertilized lawns.  Brown patch, also known as rhizoctonia blight, is most active when grass remains wet and temperatures reach 80 to 90 degrees Fahrenheit. Look for: Dark, water-soaked looking grass turning into browned-out circular areas several inches to several feet in diameter. Some green leaves may persist within the patch, and roots remain intact. In addition, blades may have irregular…