Turfgrass Disease Library

Straw-colored spots the size of a silver dollar on closely mowed turf. White mycelium may be visible in the early morning.

Circular, brown patches ranging from a few inches to several feet in diameter. A smoke-ring of gray mycelium may border active patches in early morning.

Greasy, water-soaked patches that collapse and mat within hours. Cottony white mycelium is visible in early morning and can spread rapidly in streaks following drainage patterns.

Two phases: foliar blight (yellowing leaf blades with black acervuli visible under magnification) and basal rot (crown and stem rot causing plant death). Most destructive on annual bluegrass putting greens.

Oblong to diamond-shaped lesions with gray centers and dark brown borders. Severe infections cause a "blasted" appearance as large areas of turf turn brown rapidly.

Irregular yellowing and thinning patches in warm-season grasses, often first appearing in spring. Roots are short, dark, and rotted. Stolons and rhizomes show dark lesions.

Circular to irregular patches of wilted, straw-colored turf in summer. Patch margins often have a "frog-eye" pattern with a green center of less-susceptible grasses. Roots and crowns are dark brown to black.

Circular salmon-pink to orange-brown patches ranging from 2–12 inches in diameter. Pink mycelium may be visible at the margin. Does not require snow cover — active throughout the cool, wet season.

Large, irregular to circular patches of orange-brown turf that can reach 20+ feet in diameter. The orange-brown color at patch margins is diagnostic. Most active during spring green-up and fall dormancy.

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.