Some things in nature are a delight to observe. Rainbows, thunderstorms, and fungus, well, specifically fairy ring fungus. Fairy rings are near perfect circles of toadstools, often seen in the lawn following a period of wet weather. Fairy rings can also be observed as a ring of abnormal turf that is a bright green or a halo of dead grass. Lore surrounds these curious circular formations. As far back as Medieval times, people believed fairy rings appeared after a band of fairies had danced on the lawn.
Today, we know it is not dancing fairies creating the rings in our yards. Fairy rings come from a fungus commonly found on lawns and golf courses where soils have a high level of organic matter, or in areas where trees have recently been removed. The decaying organic matter buried in the soil is beset by all manner of organisms to decompose the material and return those nutrients to the soil. Sometimes one of those organisms is the fairy ring fungus.
The growth of the fairy ring starts at the center of the ring and over the years, it will expand outward increasing the diameter of the ring each growing season.
There are three different types of fairy ring fungus. Which type you may have, depends on the growing conditions of your yard.
Type 1 fairy ring occurs commonly on golf course fairways and putting greens. Type 1 fairy rings produce a compound in the soil that reduces the amount of water that can be absorbed, creating drought-like conditions in the soil despite a dedicated irrigation system. Often Type 1 fairy rings produce a ring of dead grass and can be the most damaging of the three.
Type 2 fairy rings efficiently convert organic matter back to soil nutrients. Type 2 fairy rings are such efficient decomposers they tend to produce an abundance of nitrogen, creating dense, bright green rings of grass in the lawn.
Type 3 fairy rings may have a darker green ring color, but these are known mostly to produce rings of toadstools during wet weather, often seen in the fall.
What should a homeowner do about fairy rings? I suggest to enjoy the spectacular show and observe the expansion of the ring year after year. Fairy rings in home lawns are cosmetic and often do not kill grass. Fairy rings will disappear with time as the buried organic matter is converted back to soil nutrients.
However, some homeowners prefer to manage and if possible eliminate fairy rings. Core aeration is the best method to reduce thatch buildup in lawns, which can harbor the fairy ring fungus. If you have the bright green circles of lawn due to Type 2 fairy ring, apply a nitrogen fertilizer, so the rest of the yard matches the fairy ring. If the mushrooms of Type 3 fairy ring is bothersome, remove with gloved hands, or rake them out. DO NOT eat these mushrooms. Even though fairy rings are a fungus, fungicides are not an effective means of control.