Fairy rings are caused by many species of mushroom-forming fungi that cause rings or arcs of dead grass or rings of stimulated grass. These rings are variable in size and are sometimes followed by rings of mushrooms during rainy seasons.
- All turfgrasses can be affected especially when grasses are grown under droughty conditions or when grown in low fertility soils.
- The primary symptoms are arcs and rings of thin or dying grass or ribbons of darker faster-growing grass within the turf.
- The areas within the rings are typically drier than the surrounding soil and may be extensively colonized by the white thread-like network of fungal strands of the organism causing the problem. This fungal colonization often renders the soil impermeable to water penetration.
- Fairy rings are variable in size from a few inches to over 200 feet in diameter.
- The rings or arcs typically become larger each year, however, two rings will not cross each other, and on slopes, the bottom of the ring is typically open forming an arc. Ring symptoms may fade during the fall and winter due to turf dormancy.
- Mushrooms may occur suddenly along the outline of the ring, typically when adequate moisture is present, or may not occur for several years.
Fairy ring symptoms can be visible throughout the year.
Turf grown under droughty or low fertility conditions appears to be the most susceptible.
- While not a cure, adequate water, and fertilizer applications will often mask fairy ring symptoms. This method involves aeration, deep irrigation, and fertilization. Aeration is necessary to help water and air penetration. Irrigation can be aided by the use of a deep root feeder attached to a garden hose. If available the use of wetting agents is recommended. Irrigation should be repeated at the earliest signs of drought stress. Fertilization rates should be within the Lawn Fertilizer Schedule (table).
- Other more time and money intensive methods involve removing or killing the turf with a nonselective herbicide. Then the area is either thoroughly rototilled before reseeding or the existing soil is excavated and replaced before reseeding.