University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Fairy Rings Common in Lawns

June 28, 2001

Fairy rings may appear in a variety of ways in lawns and other turf areas. Probably the most common are large circles or arcs of darker green, taller grass. Sometimes mushrooms appear in that same ring or arc. In other cases, the arc is dead brown grass.

Fairy rings appear as a result of fungi breaking down organic matter in the soil, not actually attacking grass. Nitrogen is released for grass above to use, causing the green ring. Mushrooms appearing under wet conditions are the fruiting bodies of the fungus. If fairy ring fungi (mycelia) get very dense and inhibit water movement into the soil, grass in the arc may turn brown. Mycelia may also deplete soil nutrients and produce toxic levels of hydrogen cyanide.

Why do fairy rings appear in a particular spot? The "food" source is often old tree stumps, roots, logs, lumber, and other larger pieces of organic material in the soil. Once this material is depleted the fairy ring will disappear, but it may take considerable time. Several fairy rings often appear relatively close together on lawns growing on sites that were previously wooded areas. Notice the rings do not cross each other, as fungus activity ceases when fungi from different rings contact each other.

There are some ways to manage fairy ring. Prior to planting lawns, be sure to remove tree stumps, large roots and construction lumber buried in the area. When renovating turf areas with fairy ring, be sure to blend all soil together, as different fairy ring fungi will attack each other. If several rings are visible at the time of renovation, collect the white mycelia from each and mix it together, then spread over the soil and work it in.

Fairy ring appearing as green arcs in established lawns can be masked somewhat by increased watering and fertilizing of the grass, keeping within suggested lawn care guidelines. Lawns watered and fertilized on a regular basis tend to have fewer problems with fairy ring. Delay fertilizing until about Labor Day, however. In addition, large quantities of water may be pumped into the soil in and around the rings using a root-feeder attachment to a garden hose.

 

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