Fairy Rings in Turfgrass
By Karen Weiland, Advanced Master Gardener
During the spring or summer you may have noticed rings of lush growing grass in the lawn. This ring is a turf disease called fairy ring.
There are three kinds of fairy rings. One kind appears as lush growing grass, another as just a ring of mushrooms and the third one combines the lush grass with the mushrooms.
The rings can vary in size from one to ten feet and may not always appear as a full circle, but as a semi-circle or just fragments of a circle. The lush growth is caused by the release of nutrients, particularly nitrogen. Fairy ring fungi feed on decaying organic matter and often appear where a tree has been removed and decaying tree roots are present or where there is an old, thick layer of thatch in the turf. There may be an area of dead grass just outside the ring of lush grass. This happens because the soil is compacted as the fungi move through it, making it difficult for water to penetrate.
Like most fungi, the fairy ring fungi survive the winter in the thatch and soil. In the spring, the dormant fungi becomes active and continues to grow outward during the summer and into the fall. Mushrooms may appear in the turf after a heavy rain or watering.
To prevent fairy ring, clean up all remnants of wood and keep the thatch layer to under one half inch. If fairy ring is already present in your lawn there are a few cultural practices that can help to eliminate or mask the problem. To disguise the lush ring, apply nitrogen fertilizer on all of the lawn except the ring of grass. All of the grass will then be dark and lush and yes, you may have to mow a bit more often.
To reduce the compaction caused by fairy ring, heavily aerate the affected area. This will allow more water to penetrate the soil surface and hopefully keep the grass from drying out and turning brown.
There are a few fungal products on the market for fairy ring control. Most research says they are a waste of money and the effect may only be temporary as the organic matter that the fungi feed on are still in the soil. Most fairy rings will outgrow themselves in about four to five years. Be patient, they will eventually fade.
As always, Happy Gardening!
More information about gardening and related subjects is available online at www.hort.purdue.edu/ext/garden_pubs The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange Co., 636-2111 in Noble Co., 925-2562 in DeKalb Co. and 668-1000 in Steuben Co.
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