Dollar Spot

The causal agent for Dollar Spot is Sclerotinia homoeocarpa and all turf grass species can be affected.

Problem Overview

The causal agent for Dollar Spot is Sclerotinia homoeocarpa and all turf grass species can be affected. The favourable conditions for this disease which is a common occurrence in the top half of the North Island are when the plant leaves are wet for extended periods of time particularly from mid-spring until autumn. The symptoms are numerous small bleached spots which may coalesce to form large irregular patches. These spots may vary is size from the size of a 50c coin up to 50mm. Recovery is usually rapid as the roots are not affected.

The disease affects most turf grass species but turf containing bent grasses like NZ Browntop and creeping fescues are most susceptible whereas Tall fescue appears to be resistant. Conditions such as drought, thick thatch build up and low fertility favour the establishment of Dollar Spot. The fungus also favours heavy compacted soils with high pH.

Solutions

In the first instance apply a nitrogenous fertilizer such as Turf Supreme at 35gms/m2 or 3.5kgs per 100m2. Ensure that this fertilizer is applied prior to impending rain, during rain or alternatively water the lawn thoroughly after application. If conditions persist then a fungicide application such as Taratek may be required but this would be rare. Other treatments that are beneficial include reducing the pH by the application of acidic fertilisers, dethatching and oversowing with more resistant species.

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