To control an established fairy ring, aerate the entire diseased area every 4 inches plus an additional 2 feet. Areas of dark green grass often can be masked with light applications of nitrogen fertilizers that stimulate adjacent turf growth. Fairy ring is a common disease of Kentucky bluegrass and most other turfgrass species. It is caused by many mushroom fungi that live in the soil and thatch layer. Damage often is unsightly and sometimes a serious problem even on well-maintained lawns.
Fairy rings develop over a wide range of fertility levels and soil and climatic conditions.
The disease tends to be worse on lawns maintained at low soil moisture and fertility levels. Symptoms Early symptoms of infection appear as circular or partial ring-bands of lush green grass that vary from less than 1 foot to many feet in diameter. Most rings range from 3 to 12 feet. Eventually the deep green grass in the ring-band dies. Mushrooms or puffballs of the fungus may appear in the rings following periods of wet weather.