Dollar Spot of Turf

Sclerotinia homeocarpa

Synonyms: Sclerotinia homoeocarpa

Description:

A number of fungi cause this ill defined disease which is characterised by round patches of dead turf usually 1.5-5 cm diameter and are rarely greater than 5 cm. Initially the spots are brown and become straw coloured and may coalesce to form irregular patches. Fine cotton like threads of fungal mycelia can sometimes be seen when the turf is wet. Individual leaves may have small lesions that turn from a yellow brown to straw colour with a red-brown border. The lesion can be as wide as the leaf and there may be one to many lesions on each leaf. It occurs mainly on low cut lawns when there has been wet weather or regular dews in autumn or spring. White fluffy fungal hyphae can sometimes be seen.

Species Affected:

Most turf species. Bent grass is probably the most susceptible.

Biology:

High humidity and temperatures from 15 to 300C favour development.
It is often worse in warm humid weather followed by cold dew forming nights.
It tends to be worse in turf with low nitrogen status, growing in dry soils.
Soil pH has little effect on the disease.

Life Cycle:

The fungus over winters as sclerotia in the soil and as dormant mycelia in the roots and crowns of infected plants.

Origin and History:

Distribution:

All states.
Often worst in coastal areas.

Significance:

Management and Control:

Avoid nitrogen deficiency, drought and night watering.
Apply nitrogen especially in spring and early summer.
Increase watering to avoid drought stress but reduce the frequency as much as possible.
Apply fungicides.
Mow regularly. Reduce thatch. Increase air circulation and reduce shading and remove dew early in the day.

Related and Similar Species:

References:

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.