Have mushrooms in your yard? Here’s what you should know about the fungi in your lawn

I was taking a walk in my neighborhood and noticed that several of my neighbors had various mushrooms growing in their lawns. Mushrooms, sometimes called toadstools, are the visible reproductive (fruiting) structures of some types of fungi. Although the umbrella-shaped fruiting body is the most common and well known, mushrooms display a great variety of shapes, sizes, and colors. Some other fruiting bodies encountered in lawns include puffballs, stinkhorns, and bird’s nests, descriptive names that reveal the diversity of forms among mushrooms. Regardless of shape, the purpose of all fruiting bodies is to house and then disseminate spores, the reproductive units of fungi.

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Many fungi, including most that cause lawn diseases, have very small fruiting bodies that are hardly noticeable, and they don’t produce typical mushrooms or obvious fruiting structures. Most fungi in lawns are beneficial, because they decompose organic matter, thereby releasing nutrients that are then available for plant growth.

LIFE CYCLE

Fungal fruiting structures release tiny spores that are easily carried on air currents to new sites. When spores reach a favorable place to grow, they germinate and send out long thin filaments called hyphae. Hyphae of some fungi decompose wood, fallen leaves, and other organic matter, absorbing a portion as food. Other fungi live in a beneficial association with plants, while others parasitize and cause diseases of plants. A single hypha is too small to be seen without magnification; however, in soil or beneath bark, groups of hyphae sometimes are visible as a mass of white or dark threadlike growth known as mycelium.

When mycelium has developed sufficiently, fruiting bodies such as mushrooms can be produced. Fungi generally survive in soil for years and produce fruiting structures only when conditions are favorable, such as after periods of prolonged wet weather.

IDENTIFICATION AND MANAGEMENT

Because mushrooms are merely the fruiting bodies of fungi, removing them doesn’t kill the underground mycelia from which they are growing. Picking mushrooms, puffballs, stinkhorns, or other reproductive structures soon after they appear might prevent their spores from spreading to new sites. However, because most spores are windblown long distances, they can easily come into a lawn from neighboring areas. The primary reasons for removing mushrooms from lawns are to keep them away from children and pets and to improve a lawn’s appearance.

Caution: Some mushrooms are poisonous!

Do not eat wild mushrooms or other fungal fruiting bodies unless you are well acquainted with the different species. Many species are poisonous, and ONLY an expert can distinguish between edible and poisonous species. There are no simple tests that can be used to identify poisonous mushrooms.

Small children tend to put anything, including mushrooms, in their mouths, so remove all obvious fungal reproductive structures from the yard before allowing a child to play there. Pets also can be harmed by ingesting poisonous mushrooms.

For more information on poisonous mushrooms in California, visit the Bay Area Mycological Society website. To read more about the different types of mushrooms and fungi you might find in your lawn, visit the UC IPM website: ipm.ucanr.edu.

Information for this article was excerpted from the UC IPM Pest Note # 74100.

If you have a gardening related question you can contact the UC Master Gardeners at (209) 953-6112. More information can be found on our website, ucanr.edu/sjmg.