Southern blight
Athelia rolfsii (anamorph Sclerotium rolfsii)
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.
Identification
Circular to crescent patches enlarging up to ~2–3 m, with turf turning reddish-brown as it dies. White cottony mycelium fans over the surface in humid conditions; small (1–2 mm) tan-to-brown sclerotia resembling mustard seeds form at stem bases and in thatch — the diagnostic sign.
Symptoms
Expanding circular or crescent dead patches, reddish-brown. White mycelial growth at the advancing margin. Mustard-seed-like tan/brown sclerotia at the crown and in thatch
Signs
Circular to crescent patches enlarging up to ~2-3 m, with turf turning reddish-brown as it dies. White cottony mycelium fans over the surface in humid conditions; small (1-2 mm) tan-to-brown sclerotia resembling mustard seeds form at stem bases and in thatch , the diagnostic sign.
Biology
Southern blight is caused by Athelia rolfsii, formerly known by the anamorph Sclerotium rolfsii. The fungus survives in thatch and soil as sclerotia and produces white surface mycelium during hot, humid weather.
Epidemiology
Hot temperatures (30-35°C) with prolonged high humidity (>90%); heavy thatch and excess moisture. Often follows extended hot, wet spells.
Favorable Conditions
Hot temperatures (30–35°C) with prolonged high humidity (>90%); heavy thatch and excess moisture. Often follows extended hot, wet spells.
Cultural Management
Avoid over-irrigation; improve drainage and air movement. Reduce thatch and remove or dilute infested debris. Avoid excess nitrogen during hot, humid periods
Further Reading
University extension resources — open in a new tab.
Related Reports
No published reports yet for this pest.
Reports will appear here as they are peer-reviewed and published.