We frequently get calls in spring and fall from folks who are concerned about toadstools in their lawn.
At first blush it can be alarming to see a large ”fruiting body’’ emerging from your lawn seemingly overnight. Rest assured, these mushrooms are not damaging and are an indication of the healthy community of mycological processes happening in your soil. Fungal spores of some species can lay dormant under your turf for years until just the right conditions cause them to start reproducing. If the look of the mushrooms isn’t to your liking, mow them down and they will reintegrate back into the soil.
The exception to the benign lawn mushroom would be one of over sixty varieties of basidiomycete fungus that are wood destroyers and can be found under turf where wood or bark mulch is rotting in the soil. This can form a “fairy ring” in your lawn, an expanding green ring full of toadstools, leaving yellow or brown turf in its wake caused by mycelial fibers crowding the soil layer and creating a hydrophobic mat. While Fairy ring is rarely fatal to turf, its aesthetic effects can be of concern to golf course managers and those looking for an unblemished look for their turf. These rings can keep expanding until they run off the edge of the turf and into woods, flower beds or adjacent lawn areas.
Chemical treatments are marginally effective as it is difficult to get the material all the way through the turf and into the soil profile. Raking the puffball mushrooms up, aerating the soil in and around the ring and then flooding the turf with water will help mitigate the spread of Fairy ring. Fertilizing the area will also help mask the chlorotic look left by the fungus.
These large mushroom sightings are not what turf managers are concerned about when we talk about lawn fungus. It’s the microdochium group of fungi that can cause serious damage to your lawn in fall and winter. Search “microdochium” for more information.