Turfgrass Disease Library

Blue/green algae (cyanobacteria) form slimy black crusts and thinning patches on wet, thin putting-green turf.

Anthracnose basal rot, caused by Colletotrichum cereale, shows as orange-to-yellow individual plants in a non-descript pattern, with black setae on the leaves and black infection mats at the crown.

A cosmetic but alarming blight that straw-colors large areas of Kentucky bluegrass almost overnight, usually after swings between wet and hot/dry weather.

A relatively new bacterial disease of creeping bentgrass putting greens (first reported 2009), usually superficial but occasionally damaging.

A bacterial disease of close-cut annual bluegrass and certain bentgrass cultivars causing rapid wilt and decline.

A patch disease primarily of young creeping bentgrass greens, producing small reddish, sunken spots.

A hot-weather foliar disease producing roughly circular brown patches, often with a smoke ring.

A Rhizoctonia-like disease of annual bluegrass greens producing yellow-to-bronze rings.

A warm-weather disease of bentgrass producing small copper-pink spots on acidic soils.

A heat- and stress-driven root/crown rot and leaf blight that fades turf into mottled green, then irregular reddish-brown dead patches.

A complex of seedling diseases that rot seed before emergence or collapse young seedlings after emergence, thinning new stands.

The most economically important disease of golf turf, producing small silver-dollar-sized sunken spots.

Soil-inhabiting fungi forming rings or arcs of stimulated, dead, or mushroom-bearing turf.

An aggressive foliar blight of perennial ryegrass and St. Augustinegrass that can collapse stands rapidly.

A patch disease of warm-season turf active when grass enters or exits dormancy.

A soilborne Rhizoctonia disease of ultradwarf bermudagrass greens causing diffuse leaf and sheath necrosis. Caused by the same pathogen as mini ring -- the two names describe different symptom expressions of one disease.

Systemic smut fungi that stunt and streak older stands of Kentucky bluegrass, splitting leaves into ribbons that release black spore dust.

A Helminthosporium complex causing leaf lesions then crown/root rot (melting out) and stand thinning.

A typically minor leaf blight that affects stressed or senescing turf, often following other stresses.

A cool-wet-weather patch disease (also called pink snow mold) that, unlike gray snow mold, does not require snow cover.

A soilborne Rhizoctonia disease of ultradwarf bermudagrass greens producing bronze rings or patches. Caused by the same pathogen as leaf and sheath spot -- the two names describe different symptom expressions of one disease.

A root-rotting patch disease of Kentucky bluegrass producing frog-eye rings.

A low-fertility foliar disease, once grouped with red thread, that forms a pink film on leaves but lacks red thread’s leaf-tip threads.

A white powdery foliar fungus most common on Kentucky bluegrass in shade.

An aggressive, fast-spreading disease that can destroy stands of turf within hours under hot, wet conditions.

A root-infecting Pythium disease of bentgrass greens that limits rooting and shows as summer decline.

A root rot of poorly drained putting greens, caused by several Pythium species, that thins turf in wet and high-traffic areas.

A salinity-driven disease of cool-season turf — especially annual bluegrass and ryegrass — that rapidly collapses patches where irrigation water or soils are salty.

A Helminthosporium-type leaf spot of bentgrass causing reddish lesions and thinning.

A foliar disease of low-fertility turf producing pink-red threads (sclerotia) at leaf tips.

Foliar rust fungi producing orange-yellow pustules that rub off as powder onto shoes and equipment.

Saprophytic organisms that crawl onto turf and produce crusty spore masses; harmless to grass.

Cold-weather diseases that develop under snow cover or in cold, wet conditions.

A hot-weather blight that kills turf in expanding rings or crescents, recognized by white mycelium and mustard-seed-like tan sclerotia at the plant base.

The most damaging disease of bermudagrass, leaving circular dead patches that emerge from dormancy.

A root-infecting disease producing frog-eye patches during hot weather, though infection begins earlier.

A root and crown disease of bentgrass producing reddish-bronze sunken rings, especially on sandy, high-pH sites.

A warm-season root-rotting disease that thins turf into yellow, irregular patches — common on stressed St. Augustinegrass and bermudagrass.

A thatch-degrading fungus (artillery/cannon fungus) associated with localized thatch collapse and depressions.

A warm-weather blight primarily of fescues, producing white patches with pink-salmon borders.

A cool-weather Rhizoctonia disease producing yellow rings and patches, usually cosmetic.

An uncommon, mostly cosmetic disease of Kentucky bluegrass caused by a fairy-ring relative, appearing as yellow rings.

A downy mildew producing small yellow tufts of densely clustered shoots; mostly cosmetic.