According to Jay Chism, agronomy specialist, University of Missouri Extension, mushrooms may be unsightly to home owners, but they do very little damage to lawns and trees.
“In some cases, mushrooms actually benefit the landscape by releasing nutrients,” said Chism. Grass inside the rings is darker green and may grow taller as nutrients released as organic matter is decomposed by the fungal bodies.
The mushrooms also may grow in a circle, forming "fairy rings". The soil inside the ring becomes engulfed with fungal growth that water cannot penetrate causing patches of grass to dry out.
“Generally, homeowners can just mow over the mushrooms with the lawnmower, and not worry too much about them,” said Chism. “If you are having some dead areas appear, aerating those spots with a soil probe or using a core aerator will help alleviate the problem.”
Many homeowners are also concerned about mushrooms being poisonous to children and pets and want to apply fungicides because of this concern.
“Mushrooms and toadstools -- for the most part -- are unaffected by the application of fungicides,” said Chism. “The best solution for most people is to remove the mushrooms by hand or simply mow them off.”