The appearance of white, ball-shaped mushrooms in your grass can be alarming, but puffball mushrooms are more of a nuisance than a cause for panic. Puffball mushrooms are members of the class Basiciomycota. Although puffballs can be unsightly, and some even poisonous, controlling them with chemicals is not usually necessary.
Puffball fruiting bodies, or mushrooms, are spherical or pearlike in shape and usually about 1 inch or less in diameter. Some puffballs grow to more than 1 foot in diameter and can weigh several pounds, but typically they are not found in turfgrass. Young puffballs of most species are creamy white on both their inside and outside. As they mature, their inside takes on a yellow color. When the puffballs are fully mature, their inside becomes a dark green to purple mass of spores. The fruiting bodies eventually rupture, and spores are released. When that occurs, the outer skin may remain intact with only a hole at the top, or it may break into large pieces.
The spores produced by puffball mushrooms are carried by wind to new locations. Spores that reach a lawn germinate and send out hyphae, which are long filaments or strands. The strands support the fruiting body of the fungus when it is produced, and they decompose organic matter in the lawn. Individual hyphae are difficult to see without magnification, but when the fungus has produced a mass of hyphae, referred to as mycelia, you may be able to make out the threadlike mass. When the mycelia have developed enough and favorable conditions are present, typically about late summer to fall, fruiting bodies are produced. The fruiting bodies create new spores, and the cycle repeats. Puffball fungi can survive in a lawn’s soil for years, producing fruiting structures only when conditions are favorable for their growth, such as when prolonged periods of wetness occur.
Although some species of puffball mushrooms are edible, others are poisonous. Poisonous puffball mushrooms include hard-rind puffballs from the Vascellum species of fungi and false puffballs from the Scleroderma species, which have a thick skin and are usually dark inside even when young. Avoid illness by not eating any puffballs until they have been identified by an expert as an edible species. If you have children and/or pets, remove all fruiting bodies as you find them in your lawn to prevent their ingestion.
Puffball fungi are not parasitic or infectious, according to a University of California Integrated Pest Management Online article. So they don’t require control to ensure your lawn's health, but they are unsightly, and some can be foul-smelling or, as mentioned, poisonous. Because puffballs grow on decaying organic matter, usually they are found in areas of lawn that are high in organic material. When the material is used up, they will disappear, but that can take a long time. Although puffballs' total eradication is difficult, you can limit the appearance of puffballs by digging up fruiting bodies and roots as you see them and by controlling the amount of organic material in your lawn. This means cleaning away leaf debris and removing old stumps and roots.
- University of Nebraska–Lincoln Cooperative Extension: Mushrooms, Puffballs, Fairy Rings and Slime Molds in Turfgrass
- University of Wisconsin Plant Teaching Collection: Tom Volk’s Fungus of the Month for August 1998
- University of California Integrated Pest Management Online: Mushrooms and Other Nuisance Fungi in Lawns Management Guidelines
- Univeristy of California-Riverside: Basidiomycota and Heterobasidiomycetes
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