My Lawn Has Brown Spots & Mushrooms

Homeowners often find brown spots on their lawn. When brown spots appear with rings of mushrooms it is the result of a condition known as fairy ring, which received its name from the ancient belief that faeries had danced there the evening before the mushrooms appeared.

Fairy ring is a fungal disease that lives in the soil and remains there for many years. Warm-season grasses are the most commonly affected by fairy rings. This condition occurs most often in the spring and summer, especially in areas that are very humid. According to the University of Florida IFAS Extension, there are three types of fairy rings. Type II fairy ring is used to describe brown spots in lawn grass with mushrooms growing in a ring.

Type II fairy rings cause dark green to brown band in lawn grass, which measure from just a few inches in diameter to over 50 feet wide. Mushrooms are the fruiting bodies of the fungus, growing in a ring around the outside of the dark green or brown bands. Mushrooms appear after heavy irrigation or extended periods of rain.

Fair rings are caused by several types of fungus such as Lepiota, Marasmius, Chlorophyllum and Lycoperdon. This condition most commonly occurs when organic matter such as tree stumps or logs, exist in large quantities. Fairy ring fungi feed off the organic matter, which causes the fruiting bodies or mushrooms to grow.

Some fairy ring mushrooms are poisonous and should be destroyed. Applications of nitrogen-based fertilizers can improve the appearance of the grass, once the mushrooms are removed. Fungicides may reduce the development of fairy rings, but the fungus can remain active in the soil for as long as five years. If left untreated, fairy rings will eventually disappear on their own.