For centuries, dancing witches, little people and enormous toads have all been blamed for a common lawn problem--fairy ring.  While the homeowners of long ago attributed the rings to mythical creatures, today's homeowners may be rest assured that fairy ring is caused by any one of fifty species of fungus.

Fairy ring is the appearance of dark green rings and/or mushrooms on the lawn, in one of three patterns.  The first pattern is created when mushrooms form a ring for a short period of time, without the accompanying discoloration of grass.  The second pattern displays the typical dark green ring, as well as the presence of mushrooms.  Finally, the third pattern is similar to the second, but the grass inside the ring dies.

Kentucky bluegrass is most commonly affected, although many other turfgrasses are susceptible.

The first signs of fairy ring a homeowner may notice are small clumps of mushrooms popping up, or groupings of dark green grass.  As time progresses, these will spread.  Patterns in excess of ten feet have been witnessed, but tend to stay between one and ten feet in diameter, with varying widths.

As the fungus causing the fairy ring grows within the lawn, it breaks down organic matter.  This process results in additional nitrogen becoming available to the grass, creating the dark green appearance.  Eventually, mycelium from the fungus will grow into such a dense mat, the grass in the center of the ring may die from water deprivation.  When this occurs, the fairy ring begins to expand in search of new organic matter to consume.

Positively identifying fairy ring can be difficult, as many other turfgrass diseases present themselves in similar fashion.  Key signs to look for include:  a musty odor, white moldy growth in the top layer of soil, or the presence of mushrooms.

Fairy ring is most likely to occur in lawns that have had organic materials, such as stumps or old lumber, embedded in the soil prior to planting a lawn.  This condition is exacerbated in lawns experiencing nutritional deficiency and low moisture, although symptoms begin to exhibit after periods of moderate rainfall.

Control of fairy ring is difficult at best.  One option is to increase water and fertilization programs for the areas within and immediately outside of the fairy ring.  A tree root feeder, planted 10-24 inches deep into the soil, may be used to treat these areas by repeated deep-watering at intervals of two to three weeks.  Caution should be used to prevent overfertilization, as this may actually encourage growth of new fairy rings.

Reducing thatch by aerating every four inches in the affected areas may also limit the spread of fairy rings within the lawn, as it substantially decreases the amount of organic matter available to the fungus.  Additionally, water saturation is promoted.  Be sure to disinfect cultivation equipment after aeration to prevent the spread of fungus to healthy sections of lawn.

Homeowners with only small fairy rings may be best off to remove the rings entirely.  This may be accomplished by removing sod within the ring and up to two feet on either side and destroying it.  Under no circumstances should it be composted.  With the sod removed, remove 12 to 18 inches of the soil underneath and discard this as well, taking good care not to spill onto healthy sections of lawn.  Once this is accomplished, the area may be refilled with new topsoil and new grass installed.

A final option exists to eliminate fairy ring.  When several fairy rings exist in the same area, they are antagonistic to each other, causing the death of each.  Applying glyphosate, such as Roundup, to the affected area will kill the turf.  Sod should then be removed and the entire area rototilled, mixing the mycelium from the rings to promote this antagonistic behavior.  Thoroughly soak the area with the aid of a wetting agent and replant.

Fairy ring is frustrating for many homeowners.  For more information, please call 539-6447 or stop by the Extension office.