Fairy Ring

Various basidiomycete fungi (Marasmius oreades, Agaricus spp., Lycoperdon spp., and many others)

All Turfgrasses Moderate Fungus

Symptoms

Three types: Type I (rings of dead turf), Type II (rings of dark green, stimulated turf), Type III (rings of mushrooms only with no turf effect). Rings expand outward each year as the mycelium grows.

Type I: rings or arcs of dead or severely wilted turf caused by hydrophobic mycelium that prevents water infiltration
Type II: rings of dark green, lush turf caused by nitrogen release from decomposing organic matter
Type III: rings of mushrooms or puffballs with no visible effect on turf color or health
Affected soil often smells musty or mushroom-like when excavated
Hydrophobic soil (Type I) does not wet even after rain — water beads on the surface
Rings typically expand 6–24 inches per year and can persist indefinitely

Signs

Mushrooms (e.g., Marasmius oreades — tan, umbrella-shaped) or puffballs emerging in rings or arcs — most visible after rain
Dense white mycelium visible when turf or thatch is pulled back in the active zone
Hydrophobic soil in the dead zone has a characteristic musty, mushroom-like odor
The ring pattern itself — circular or arc-shaped, expanding outward annually — is the most reliable field sign

Biology

Fairy ring fungi grow outward from a central point, decomposing organic matter. As the mycelium matures at the center, it may become hydrophobic, blocking water infiltration and causing turf death. The outer ring of stimulated growth results from nitrogen and other nutrients released by the decomposing mycelium. Fruiting bodies (mushrooms) appear seasonally.

Favorable Conditions

Temperature range: 60–80°F with adequate soil moisture

Sandy soils or soils high in organic matter
Buried organic debris (stumps, roots, construction debris)
Thatch accumulation providing substrate for fungal growth
Moderate soil temperatures and moisture
Old, established turf where mycelium has had time to accumulate

Cultural Practices

Core aerate rings aggressively and water thoroughly to break hydrophobic mycelium
Apply a surfactant to hydrophobic Type I rings to improve water penetration
Remove mushrooms and puffballs before they mature and release spores
Excavate deeply to remove buried organic debris that fuels the fungus
Reduce thatch through vertical mowing and topdressing
Mask stimulated green rings with supplemental nitrogen to the surrounding turf

Related Reports

No published reports yet for this disease.

Reports will appear here as they are peer-reviewed and published.