Lawn Mold: Signs and Treatment for Slime Mold On Your Lawn

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Slime Mold We have received this type of question from several homeowners, stating that their lawn has “mold” and want to know how to correct the problem. The term mold can mean any number of maladies that may affect a lawn that cause turf to turn brown across the entire lawn, in small spots or rings, or in irregular shapes. For those of us in the lawn care industry, lawn mold usually refers to Slime Mold, a non-serious condition that can occur on lawns, usually occurring in the summer, especially after a good rain.

How does Slime Mold Develop?

Slime molds are primitive organisms called saprophytes. These are the organisms that are responsible for breaking down dead or decaying matter through their feeding processes. There are saprophytes that break down the dead oak tree in the forest and saprophytes that break down dead grass blades in the lawn. Some saprophytes are considered diseases in turf grasses. The most common saprophytic disease is Dollar Spot. These organisms obtain their nourishment from live grass blades. In the case of the Slime Molds, they only use the grass blades as a structure on which to “grow” spores. The organism produces small fruiting bodies on the outside of the leaf surface and they grow perpendicular to it. Initially, the fruiting bodies are about the size of a pin head, but grow larger as more spores are produced. The fruiting bodies range in color from dark blue, to purple to gray. When a large number of the fruiting bodies develop on numerous grass blades in the turf, these patches can range in size from a couple of inches to several feet in diameter. When homeowners find these small patches, they may kick them with their shoe and see a small “puff” of a powdery substance that arises from the area. What they are seeing is a release of spores from the slime mold. Finding a patch or two of slime mold in your lawn should not be a source of concern. In a way, it is actually a good thing as it may indicate that your lawn has plenty of microbial activity.

How To Treat Slime Mold

If you find a patch of slime mold you can either let nature take its course as the spores will fall away on their own or you can use a broom to sweep it off or a stream of water to wash it off. Normal mowing will also dislodge the spores. One thing to keep in mind is the spores that fall off will remain on the soil or in the thatch and will regrow again when the right weather conditions exist in the future. There is one other type of slime mold that will develop in mulch found in landscape beds and it is called Dog Vomit Slime Mold, getting its name from its appearance when still fresh. It is usually a tan to yellow gelatinous substance that will grow across the mulch. Once it dries out, it can easily be raked out or turned over and incorporated into the mulch. It may be ugly, but it is a natural process and should not be a concern. Contact your local neighborhood Spring-Green lawn care professional to assist with your lawn. They will provide you with the program and products to help keep your lawn healthy.