Red Thread / Pink Patch

Red Thread (Laetisaria fuciformis)
Pink Patch (Limonomyces roseipellis)

These conditions are now thought to be caused by a “complex” of two different fungi, but they often appear together and under the same environmental conditions, and are generally associated with poorly aerated lawns suffering from a lack of nitrogen. Lawns infected may have a pink to reddish cast when viewed from a distance. The condition is most noticeable in wet weather, when the affected leaves are covered with a gelatinous pink fungus, and tiny cotton wool-type spores may be seen. In drier conditions, tiny red threads of the red thread fungus may be observed extending from the leaf tips. The grass may show irregular patches of dead and dying leaves, giving the lawn a ragged and unsightly appearance, but the condition is rarely fatal to the lawn, as the roots are not affected.

These conditions can be found on many turf grass species, but are seen most often on perennial ryegrasses and fine leaf fescues. Scarifying and aerating in the autumn to improve the growing conditions plus the application of a suitable fertiliser in the spring are the best means of prevention. Lift grass clippings as the dried red threads can survive to carry the disease, enabling a later infection to occur.

If chemical treatment is required, either a systemic or contact fungicide should be used.