Advertise in Print | Subscriptions
Published August 14, 2009, 02:42 PM

Moisture brings lawn mushrooms

As a result of the rain and humid weather, mushrooms are appearing in many lawns. Their presence in the lawns prompts homeowners to search for a safe, effective chemical that will make them disappear.

By: Jim Stordahl, DL-Online

As a result of the rain and humid weather, mushrooms are appearing in many lawns. Their presence in the lawns prompts homeowners to search for a safe, effective chemical that will make them disappear. Unfortunately, such a chemical does not exist and there is little to do but let nature take its course.

Mushrooms in lawns are the reproductive, spore-producing parts of fungi that are decomposing organic matter found in the soil. These fungi often live off dead roots and chips of wood left behind when a tree or shrub died or was otherwise removed. Another source of food for the fungi is wood that has been buried following home construction.

Fungi are actually an important part of nature’s recycling system and return the nutrients from the decomposing wood to the soil. Once the material they are living on has been fully broken down and the nutrients returned to the soil, their work is done and the mushrooms disappear.

Depending on the size of the roots or wood left underground, complete decomposition could take several years or more. In the meantime, the fungi produce mushrooms whenever conditions are moist. They are rarely a problem during hotter, drier weather.

There is nothing to apply to the lawn that will eliminate the mushrooms. It usually is not practical, even if it were possible, to remove the decomposing wood from the soil. The mycelium from the mushrooms may extend three feet or more into the soil if there is a food source present. You can break the mushrooms up with a rake or hoe and let them dry up. If small children play on the lawn, you might be wise to pick them up and dispose of them in the event that they are a species that contains toxins. Don’t be surprised if you remove them one day, only to find a whole new batch the next morning.

Mushrooms often suddenly appear in fairy rings in lawns. Fairy rings consist of a ring or arc of dark green grass with an inner ring of pale green or brown grass. There are a number of fungi that produce this pattern in lawns. The fungi are feeding on organic matter in the soil and as they use up the food supply the rings expand outward until the food supply is used up.

Eradication of fairy rings is difficult and the best course to take is probably to mask the problem. The dark green rings are more obvious in nutrient deficient soils and applying fertilizer will cause all the grass in the area to grow more vigorously and will mask the ring. However, it is wise to have the soil tested as over fertilizing will cause additional problems.

Slime molds, a fungi-like organism, are being found on home lawns, in flowerpots and in wood mulch around ornamentals. They usually appear as white, yellow, gray or purplish-brown, jelly-like masses. As they dry, they appear crusty and powdery and are sometimes described as looking like “dog vomit”. Plant disease is not caused by slime molds. Control is usually not necessary and they will disappear during hot, dry weather. Slime molds may be washed, brushed, or raked from affected areas and mowing will quickly remove them from growing grass.

For more information, contact me in McIntosh on Monday and Thursday, Red Lake Falls on Tuesday, or Bagley on Wednesdays. Our toll free number is 800-450-2465. If e-mail is your thing, contact me at stordahl@umn.edu. Source: Carl Hoffman, Stearns County Extension.

Tags: