Fungus in Yards

Even fungus that isn't harmful can produce unsightly mushrooms in your yard.

There are a variety of pests and diseases that can affect the plants in your yard, but one of the most common nuisances that you may encounter are fungi. There are a wide range of fungi that may appear in your yard, and while many do not have a negative effect on your grass, they can mar your lawn's appearance with unsightly mushrooms and other fruiting structures. It is a good idea to familiarize yourself with some common types of fungi that may occur in your yard, so you know how to deal with them if they make an appearance.

Fairy Rings

Fairy rings are one of the most common types of fungi you may find in your yard. Fairy ring fungi form circular rings on grassy areas that can grow as large as 12 feet in diameter. The rings are usually green in color, and typically feature mushrooms along the perimeter. Several types of fungi may be responsible for fairy rings, including the Lepiotad and Marasmius oreades species. Fairy rings usually increase in size each year, and the growth of grass in the affected area typically slows. In some cases, the grass may eventually die. You can dig out areas of fairy ring infestation, but it can be a laborious project because you must take great care when removing the soil to prevent spreading the fungi to the surrounding areas. You can also increase watering and fertilization in the affected areas to help promote grass growth.

Armillaria

Another type of fungi that you may encounter on your lawn is the armillaria root rot fungus. This fungus is usually identified as honey-colored mushrooms that grow at the base of a tree or shrub. They appear in the fall, and affect a wide range of tree and shrub species. The fungus can actually destroy the plant's roots, eventually causing it to die. The mushrooms do not make their appearance until the tree or shrub has died or is close to death. Armillaria root rot fungus is difficult to eradicate completely, but you can prevent further spread of the fungus with pesticides like methyl bromide, chloropicrin and carbon disulfide.

Stinkhorns

As their name implies, stinkhorns are mushroom-forming fungi that produce an extremely foul odor. They appear during cooler weather, and grow into mushrooms that resemble long, thin fingers and are usually pink or orange in color. The unpleasant odor is produced by a slimy coating that covers the tip of the mushroom and usually attracts flies, ants and other insects that spread the fungus' spores. Besides their foul odor, stinkhorns do not usually pose a problem for your yard. However, if you wish to remove them, you can dig them out or pull them out by hand.

Mycorrhizae

Not all yard fungi are detrimental to your lawn and plants. Mycorrhizal fungi actually assist herbs, shrubs and trees in absorbing moisture and nutrients from the soil. The fungus usually forms mushrooms that grow at the roots of herbaceous plants, shrubs and trees. You may also spot the mushrooms across your lawn. While you may find their appearance to be somewhat unsightly, removing them can actually negatively affect your plants because certain trees, such as conifers, do not grow as heartily without the presence of mycorrhizal fungi.

References

• University of California Statement Integrated Pest Management Program; Mushrooms and Other Nuisance Fungi in Lawns; W. S. Moore, et al.; September 2002.
• North Dakota State University Agriculture; Lawn Diseases; H. Arthur Lamey, et al.; July 1996.
• United States Forest Service; Armillaria Root Disease; R.E. Williams, et al.
• University of Florida Extension; Stinkhorns are Smelly Fungi; January/February 2009.