Red Thread

Red thread is a common cause of patches of dead grass on lawns during wet summers and in autumn. It is caused by the fungus Laetisaria fuciformis.. The disease can develop at any time of year but is most common in late summer and autumn.

Symptoms of Red Thread
  • Patches of affected grass with a reddish tinge at first, later becoming light brown or almost bleached in appearance
  • Pinkish-red, gelatinous, thread-like structures (stromata), 1-2mm (less than ¼in) in length, are produced on the leaves and may bind them together

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Control of Red Thread
  • If red thread appears, application of nitrogen to the affected area will often be sufficient to control it. If there is Red Thread in the lawn in August then applying more Nitrogen must be avoided as this will cause soft growth, which is prone to snow mould.
  • In Autumn a selective fungicide can be applied
  • Aerate to improve drainage
  • Scarify to remove thatch and moss.
  • Dispose of grass clippings – do not compost.
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There is a risk of resistance occurring in the fungal population, therefore fungicide  should not be applied more than twice a year and only used as a last resort if the other control methods detailed above have not improved the situation.