Dollar Spot
Sclerotinia homoeocarpa
Disease of Foliage
Susceptible Turf
All turf species
Symptoms
- Closely mowed areas – sunken circular tan coloured spots (less than 5 cm).
- May coalesce into larger areas – especially higher mowed turf.
- Closer inspection reveals water soaked lesions that will turn tan (hourglass) with definite reddish-brown margins.
- Infection will rarely progress to crown or kill plants completely despite leaves being totally blighted.
- May be confused with early Pythium Blight and Red Thread.
- Humid, cool conditions may see the development of white mycelial growth on infected tissue.
Conditions Favouring Disease
- Temperature ranges of 15°C to 30°C and continuous high humidity.
- Warm humid weather with cool nights that produce heavy dews.
- When the micro-climate temperature reaches 16°C the fungus resumes growth.
- Low nitrogen levels.
- More severe in dry soils.
Management Tips
- Preventative fungicide program.
- Provide adequate level of nitrogen, particularly in the spring and early summer.
- Mow grass at regular intervals.
- Reduce thatch.
- Increase air circulation.
- Irrigate turf deeply and as infrequently as possible to avoid drought stress.
- Remove dew from the turf early in the day.
General Comments
This fungus overwinters as sclerotia and as a dormant mycelium in the crowns and roots of infected plants. Soil pH has little or no effect on Dollar Spot severity.