By MADDY ROHR
K-State Research and Extension news service
Certain parts of Kansas have received enough moisture this spring to cause mushroom growth in home lawns and gardens. Kansas State University horticulture expert Ward Upham said most are relatively harmless to other plant life.
“Some of these mushrooms are associated with arc-like or circular patterns in turfgrass called fairy rings. The ring pattern is caused by the outward growth of fungal mycelium,” Upham said. “The mycelium forms a dense, mat-like structure in the soil that decomposes organic matter.”
Upham said this decomposition releases nitrate into the soil, which in turn stimulates the growth of the grass at the outer portion of the ring. This results in a dark green appearance of the grass at the margin of the ring.
“Unfortunately, the thick fungal mat formed by the fungus interferes with water infiltration. The fungus also may release certain byproducts that are toxic to the turf,” Upham said. “This may lead to dieback of the turf close to the ring.”
Upham said fairy rings are difficult to control.
“You can sometimes eliminate the ring by digging to a depth of 6-12 inches and 12 inches wide on both sides of the ring, refilling the hole with non-infested soil,” Upham said.
Commercial growers can use fungicides to control fairy rings but these products are not available to homeowners.
“Some mushrooms in lawns are not associated with fairy rings. These may be mycorrhizal (symbiotic association with tree roots) or saprophytic (live on dead organic matter such as wood or other material) in the soil,” Upham said.
Upham recommended not killing these mushrooms because they can be beneficial.
“A fungicide spray to the mushroom itself does little good. Remember the mushroom is simply the fruiting structure of the organism,” he said. “Most of the fungus is below ground and inaccessible to the chemical.”
If mushrooms are a nuisance, Upham encourages picking them and disposing of them as soon as they appear. If there are too many for that to be practical, mow them off.
“Mushrooms tend to go away as soil dries. Patience may be the best control,” he said.
Upham warns that some of the mushrooms in the lawn are edible, but others are poisonous. Never eat mushrooms unless you are sure of their identity.
Upham and his colleagues in K-State's Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens. The newsletter is available to view online or can be delivered by email each week.
Interested persons can also send their garden and yard-related questions to Upham at [email protected], or contact your local K-State Research and Extension office.