Leaves are yellow, and grow faster than non-yellow leaves. The thatch under the yellow ring will be white or reddish. White, in culture. Single-celled, hyaline conidia. Pathogen survives as a saprophyte or mycelium in living tissue.
Yellow symptoms are temporary.
Toxins may be involved. Reduce fertilization and watering. Harvesting and transplanting sod that has yellow ring will eliminate the symptoms after several months. Once the disease develops, it can be expected to appear each year.