Buckeye Yard and Garden onLine

Dark green rings or arcs ranging from 2-3' to several hundred feet in diameter may be seen in lawns in the spring and fall that may or may not be accompanied by mushrooms. In severe cases, the rings die, forming ugly dead arcs in which turfgrass will not survive.

Although not completely understood, the belief in supernatural interaction has been replaced by the evidence that the rings are caused by a complex of at least 54 species of basidiomycetes fungi. The disease usually originates from mycelium growing in roots or logs which are buried in the soil. As the organic debris rots, mushrooms develop which then spread spores to adjacent turfgrass. More important than the sexual reproduction however, is the constant growth of mycelium growing outward in the thatch. As the fungi digest organic debris, not only is nitrogen released, causing the luxurious green color, but hydrogen cyanide is also secreted, damaging roots. The dense, white mycelium is impervious to water, causing turfgrass roots to die. This ring can last for years until it meets a permanent barrier, such as a sidewalk, or another fairy ring.

If a plug of the declining turfgrass is dug and examined closely, the mat of mycelium may be seen in the thatch. If the sample is moistened and placed in a plastic bag over night, the mycelium will have grown substantially throughout the thatch, and be obvious the following day.

To reduce the severity of fairy ring, dig the soil directly outside of the ring and work composted soil into the mix. In severe cases, the soil is actually removed and replaced with clean, sterilized soil. In less serious situations, a light application of fertilizer will obfuscate the green ring. Heavy rates of fertilizer are not recommended. Hand water the turf and use a wetting agent if necessary to improve penetration. Of course, one can always hope for a fairy nice miracle.

For more information, see:

• Fairy Rings in Turfgrass
• Fairy Ring Management Strategies