University of Illinois Extension

Mushrooms in the Lawn

While rain is often desperately desired for home lawns and gardens, it can bring problems, said Martha Smith, a University of Illinois Extension horticulture educator.

“High humidity and excess moisture lead to plant problems,” said Smith. “One of those ‘problems’ can pop up quickly literally overnight--mushrooms.”

Mushrooms, sometimes called toadstools, are the reproductive or fruiting stage of fungi. They are quite common following prolonged wet weather and often disappear as soon as soils start to dry.

mushrooms“The majority of mushrooms are nuisance problems, appearing repeatedly if conditions are right. They may have an odor,” she said. “They are annoying but cause no damage to the grass or to our landscape plants. Most fungi in lawns are beneficial, because they decompose organic matter buried in the soil, releasing nutrients that are then available for plant growth.”

The mushroom is the reproductive stage. At that stage, it can produce and release tiny spores that are carried by the wind to new sites. The mushrooms growing in your lawn could have blown in from your neighbor down the street or across town.

“When spores reach a favorable place to grow, they germinate and send out long, thin filaments called hyphae,” she said. “Hyphae decompose wood such as an old stump or the roots left behind from a tree cut down several years ago or construction debris buried after the house was built or the sunroom added on.

“A single hyphae is too small to be seen by the naked eye, but groups of hyphae can be visible as a mass of thread-like growth known as mycelium. When mycelium has developed sufficiently, mushrooms pop up. These nuisance fungi can survive in soil for years and will only produce fruiting structures when conditions are favorable.”

There is nothing homeowners can do to keep mushrooms from coming up. Merely removing the mushroom doesn’t remove the underground portion from which they are growing.

“But removing them will prevent them from spreading more spores that can lead to future pop-ups,” Smith said. “Simply mow them off or take them up and discard them. Remember, they may continue to appear periodically over the next several years during favorable environmental conditions until the organic matter they are feeding on is gone.

“Never eat mushrooms growing in your lawn or garden. The majority are poisonous. Removing them eliminates any potential attraction for curious children and pets.”