Deb Babcock's gardening column appears Mondays in Steamboat Today.
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Some Steamboat area residents are complaining about mushrooms popping up in their lawns this fall. As Bill Sauter said to me the other day, "It's not that I don't like them, but they're slippery when I go to mow the lawn and step on one."
The part of the mushroom that we see in the lawn actually is its fruiting body. Just pulling up the mushroom won't eradicate it from your lawn since the majority of its roots are underground. But if you pull it up before it throws off spores - or tiny reproductive seeds - you'll limit the potential for more mushrooms. The fruiting body of a mushroom has thousands of little spores that will form a network of roots under your lawn and produce more fruiting bodies when the conditions are right.
It is not easy to get rid of mushrooms in your lawn, since you need to remove all of the soil that holds the roots or spores. And since mushroom roots, called mycelium, can grow as much as half a mile a day, your entire lawn could be affected.
Instead, you can try to make the environment less conducive to mushroom growth.
Mushrooms prefer moist areas in which to grow. Therefore, you can limit mushroom growth by keeping your lawn mowed, not saturated with water, not over-fertilized, and by removing litter such as leaves, pet droppings, and grass trimmings that feed the fungus. If you haven't aerated your lawn in a while, this will help with drainage and allow for better air movement through your grass, keeping it dryer and less conducive to mushroom growth.
Fungicides are available to help control mushrooms in the lawn, but they are pretty toxic - some have been banned in recent years - and they won't completely eliminate mushrooms, anyway. Most of the fungus is below your lawn and inaccessible to these chemicals. To be truly effective, you need to remove the mushroom's food source, which often is decaying matter under your grass, often an old tree stump or similar decayed organic material.
Fairy rings are a special case different from the occasional toadstool that pops up in the lawn. Fairy rings make circles or arcs of mushrooms in the lawn and can turn areas of the grass brown and unsightly. Often, there is a tree stump underground or other similar food source sustaining these mushrooms. There's no good control for fairy ring, but you can temporarily mitigate the problem with regular mowing and with regular applications of low rates of nitrogen.
Many of the mushrooms that grow in lawns here are edible. But unless you know for certain what kind of mushroom is growing in your lawn, do not eat it. Many poisonous mushrooms look similar to edible ones.
Most mushrooms found in lawns are harmless to the grass, so if they don't bother you too much, try these steps to limit their growth. And know that as the mushroom fruiting body decomposes, it releases nutrients into your soil that grass roots can use for healthy growth.
Deb Babcock is a Master Gardener through the CSU Extension Routt. Questions? Call 879-0825.