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Does your grass have brown patches?

What is 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. Red thread will rarely kill the grass completely, and the patches will recover with appropriate remedial action. The disease can develop at any time of year, but is most common in late summer and autumn.

It is most serious on red fescue (Festuca rubra), but other fescues, bents (Agrostis spp.), perennial rye-grass (Lolium perenne) and annual meadow grass (Poa annua) are also attacked.


You may see the following symptoms:

  • Patches of affected grass with a reddish tinge at first, later becoming light brown or almost bleached in appearance
  • Patches vary in size from 7.5cm (3in) to 25cm (10in) in diameter but can be much larger

Two types of fungal growth may be seen on the patches, particularly under wet or humid conditions. Both are visible to the naked eye, but are seen better with a hand lens or magnifying glass.

  • The first takes the form of small, pink, cottony flocks, and can be confused with growth of the fungus causing snow mould
  • The second is specific to red thread, and gives the disease its common name. Pinkish-red, gelatinous, thread-like structures (stromata), 1-2mm (less than ¼in) in length, are produced on the leaves and may bind them together

If you think your lawn may be suffering from the affects of Red Thread, call us to arrange a service call to assess the condition and recommend a suitable treatment to help with its control.

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