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Fairy Ring (Clamp fungi mushrooms and approximately 50 Genera species of fungi) Fairy ring is caused by many types of basidiomycetes most of which produce mushrooms after heavy rains usually during late summer or early fall. Fairy ring can enlarge and cause severe damage or death to turfgrass. All turfgrasses are susceptible.
Fairy Ring with and without fruiting bodies
It is not known if the fungus begins by a piece of mycelium or by a spore. The fungus lives by decomposing organic matter in thatch or soil and moving radially outward. White thread-like mycelium from the fungus can grow 6 inches or more into the soil and form a hydrophobic mat which prevents water and nutrients from being absorbed by turfgrass roots. Fairy ring may also inhibit or kill turfgrass by releasing nitrogen from decomposed organic matter, which can cause a lethal accumulation of ammonia. Fairy rings may also produce toxic levels of hydrogen cyanide, directly infect roots, and weaken turf making it venerable to other diseases.
Dark green circular or semi-circular rings appear as a result of the fungus decomposing organic matter and making nitrogen available to the turfgrass. This usually occurs in dry sandy soils with a high quantity of buried organic matter such as stumps, leaves, and branches. Rings can persist for several years and increase in size each year.
Fairy ring can be difficult to control. Core aerate the infected area or spike it with a pitch fork and water thoroughly before sunrise to leach fungal toxins deeper into the soil. Wetting agents will help better distribute the water into the soil. This will help break the hydrophobic mat of mycelium. ProStar 70WP used as labeled will help control Fairy ring if combined with the above practices.