RELEASE DATE: February 6, 2015

Mushrooms and Other Strangers in
Our Lawns

By Aransas/San Patricio Master Gardeners

by Amanda Steves

What do fairy rings, toadstools, and dog-vomit slime mold have in common? They all appear mysteriously in our grass and then disappear, like magic. They are not alien creatures that have recently arrived on Earth, even though they may look like it. A circle of mushrooms, known as a fairy ring, is lovely, and those cute but deadly red and white toadstools may be charming, but a blob of slime mold is definitely not pretty.

After a day or two of heavy rain, you might see some little mushrooms popping up in your yard or flower bed. Tomorrow they won’t be so little anymore, and within a few days, they’ll be gone. Some folks like them, some want to get rid of them, and others talk about eating them. However you may feel about them, DO NOT EAT THEM.

It’s very hard to distinguish between poisonous mushrooms and edible ones. Some of the most desirable edible varieties look just like others that are extremely toxic. So be safe and don’t eat mushrooms from your lawn, garden, or local forest. If young children or pets play in your yard, you may wish to remove any mushrooms that are present. Sometimes dogs and kids will eat them, and they can become very ill with long-lasting or even fatal effects.

Are mushrooms damaging your turf? Probably not. In most cases, they spring up in areas where there’s plenty of decomposing plant material to feed upon. It’s a sign that the soil in your yard has organic matter, which holds moisture and nutrients for the grass and plants. In some instances the underground fungus that produces fairy rings can get so dense that the grass will turn brown. This fungus does not respond well to conventional fungicides. You could aerate the lawn within the ring to allow water to get through the fungal mat and to the grass roots. Another alternative is to dig up the area and dispose of the grass and soil, then bring in some clean soil and replant the grass. Generally, though, fairy rings are not so damaging, and they produce a lovely circle of mushrooms.

What is the best way to get rid of mushrooms? You can’t really eradicate or prevent the occurrence of mushrooms. When they appear in your yard or flower bed and you don’t want them, you can hit them with a forceful spray of water or use a rake to pull them out. Mushrooms are seasonal, and they won’t be a constant problem like weeds. If you do see them frequently in your yard, you may be watering too often and should cut back to no more than once or twice a week.

It’s hard to prevent mushrooms because they are propagated by spores carried on the wind. If you get them out of your yard, another crop will be on its way from someone else’s yard, field or forest. When a spore lands on decaying plant material in well-amended lawn soil or on wood mulch, it grows into a microscopic fiber, the mycelium, which lengthens and branches as it eats. If it happens to be in the vicinity of a mycelium from a different spore with the appropriate features, the two link up and become capable of reproducing. As the mycelium eats, it actually helps break down dead wood, making more nutrients available to your grass and plants. Over time, the original mycelium turns into a mass of fibers in the soil or embedded in a piece of rotting wood. When it is ready to reproduce, often because the food supply is getting low, it waits until a heavy rain and produces one or more mushrooms, which in turn produce and eject spores.

Since mushrooms are classified as fungi, their mycelia tend to take the shape of an expanding circle as they grow, like many other types of fungus. They produce mushrooms on the outer edges of the fiber mass, and that’s why fairy rings are formed as circles or arcs.

What is that stuff on the grass that looks like vomit? It’s slime mold. This is an alien-looking organism that’s not a plant, animal, or fungus. Currently it is classified by biologists as a protist, like the amoeba. It lives in the soil as individual one-celled microbes, eating bacteria. When the food supply runs low, they send out a signal to each other, and they all start glomming together to form a much larger blob. This blob is called a “slug,” and it covers itself with a slimy film. The slug actually moves about 1/25th of an inch per hour, seeking light. When the area is bright enough, it goes into reproduction mode, sprouting bunches of little spore-balls on stems. When a drop of water or gust of wind hits them, they send their spores out to the world.

Slime mold is only visible for a day or two as it prepares to send out spores. It rarely causes damage to plants unless it happens to sit on a seedling. The seedling can be smothered under the slime or die from lack of light. It’s easy to get rid of slime mold with a blast of water from your hose.

Texas A&M AgriLife Extension Service - Aransas County Office is located at 892 Airport Road in Rockport. AgriLife Extension education programs serve people of all ages, regardless of socioeconomic level, race, color, sex, religion, handicap or national origin.

References

“Mushroom Rings Invading Your Yard?” by Kevin Ong, Associate Professor & Extension Plant Pathologist, Department of Plant Pathology & Microbiology, Texas A&M University, October 2013. http://plantclinic.tamu.edu/2013/10/11/mushroom-rings-invading-your-yard/

“Master Gardener: Mushrooms on Lawn No Cause to Worry About Grass Fungus,” by Bill Sevier, Ask a Master Gardener, in Tulsa World, August 2, 2014. http://www.tulsaworld.com/scene/gardenadvice/columnists/mastergardener/master-gardener-mushrooms-on-lawn-no-cause-to-worry-about/article_c635fdd3-9188-55ac-8b3f-a941a5110f40.html

“Control of Nuisance and Detrimental Molds (Fungi) in Mulches and Composts,” HYG-3304-98, by Harry A. J. Hoitink, Department of Plant Pathology, OARDC/The Ohio State University. http://ohioline.osu.edu/hyg-fact/3000/3304.html

“Are Wild Mushrooms Toxic to Pets?” from Veterinary Insight for Pet Owners, by Christine Gowen, Pet HealthZone Editor. http://www.petinsurance.com/healthzone/pet-articles/pet-health-toxins/Are-Wild-Mushrooms-Toxic-to-Pets.aspx

“Mushrooms in the Garden Beds,” by Kevin Ong, Associate Professor & Extension Plant Pathologist, Department of Plant Pathology & Microbiology, Texas A&M University Texas Plant Disease Diagnostic Lab, Texas A&M AgriLife Extension, April 2011. https://plantclinic.tamu.edu/2011/04/25/fungi-in-the-garden-beds/

“Fairy Rings,” by Richard L. Duble, Turfgrass Specialist, Texas Cooperative Extension. http://aggie-horticulture.tamu.edu/archives/parsons/turf/publications/fairyrings.html

“Slime Mold on Lawn Grass,” by Herman Auer, Master Gardener, Texas AgriLife Extension Service, Galveston County Office. http://aggie-horticulture.tamu.edu/galveston/Gardening-Handbook/PDF-files/GH-074--slime-mold-lawn-grass.pdf.

“Slime Mold on Mulch,” by Camille Goodwin, Master Gardener, Texas AgriLife Extension Service Galveston County, 2008. http://aggie-horticulture.tamu.edu/galveston/Gardening-Handbook/PDF-files/GH-073--slime-mold-on-mulch.pdf

“Slime Molds,” by American Society for Microbiology. http://www.microbeworld.org/types-of-microbes/protista/slime-molds

“Cellular 'Slime Molds:' Dictyostelium and relatives,” by David Caprette, Experimental Biosciences, Rice University, 1996. http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/dicty.html

The Complete Book of Mushrooms, by Peter Jordan & Steven Wheeler, c.2005.

In the Company of Mushrooms, by Elio Schaechter, c.1997.