Driving around town, it’s hard to miss the fairy rings popping up in lawns. These fairy rings are cause by fungal growth and occur more often in lighter-textured soils and in grass with a significant thatch layer. They also seem to be more common in areas that were once occupied by a tree or stump. Buried construction waste can also contribute to the growth of fairy rings. The good news is that they are not considered a serious problem, unless of course you are the golf course turf manager.

Fairy rings are not considered a true infectious turf disease since the fungi do not attack the grass directly but only alter the soil chemistry and structure, thereby affecting the turf grass.

Fairy rings are caused by any of more than 50 species of soil related fungi. These fungi overwinter in the thatch layer or are buried in the soil. They feed on organic matter so a high level of thatch in your turf can contribute to fairy ring development. For those who don’t know, thatch is primarily made up of grass clippings, left in your yard after mowing.

The ever-expanding circle of fairy ring fungal growth starts at a central point and them moves outward with each year’s growth. These rings can range in size from a few inches to several hundred feet in diameter. Once established, they are hard to deter.

There are three different manifestations of fungal growth in fairy rings. Type 1 rings manifest as a circular dead patch in the turf. In this type of fairy ring, the fungus has killed the turf by causing the soil to become water repellent aka hydrophobic which causes the grass to die due to drought stress. To help control a Type 1 ring, remove the thatch layer from your turfgrass and aerate the soil to help get water to the roots. After doing this, plan on giving the area plenty of water, soaking to a depth of one to two feet at 4 to 6 week intervals.

Type 2 fairy rings manifest as a ring of what appears to be over-fertilized grass that is darker in color and growing faster than surrounding grass. This extra growth results from the nitrogen and other nutrients the fungi release into the soil. This type of fairy ring is found more often in under-fertilized or under-watered turf grasses. For Type 2 fairy rings, you can mask their location with a light application of nitrogen to the surround area.

Type 3 fairy rings are the ones we see more of around town and are the ones where seemingly overnight, mushrooms pop up in a circular or semi-circular pattern in our yards. Type 3 is the easiest to manage in that you can remove the mushrooms or mow them down. In addition, you may want to try some thatch removal.

Professional applicators have several fungicides available to them to treat for fairy rings, but homeowners must weigh the cost to control what some see as a nuisance outbreak, but others see as a special surprise to be enjoyed. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo courtesy Pixabay