Red Thread in Lawns

Red Thread in Lawns

Cool, moist weather in May and June are perfect conditions for Red Thread to show up in lawns. Red Thread (Laetisaria fuciformis) is a fungus that produces red or pink antler-like ‘threads’ on the infected grass blades. Circular patches of tan or pink about 4 to 8 inches in diameter will appear in the lawn.

The good news is that this fungus rarely causes serious damage to the lawn. It is also an indicator that the lawn may be ‘hungry’ caused by a lack of nitrogen. Application of a high nitrogen fertilizer will help the grass recover. A fungicide can be applied to keep the fungus from spreading until the nitrogen takes effect.

If you have already fertilized the lawn in spring, bring in a soil sample, so that a pH test can be done.

If the pH is too high or too low, the grass cannot take up the nitrogen that is already present in the soil also
causing a nitrogen deficiency. The results of the pH test will tell us if sulfur or lime needs to be applied
to correct the pH.

This fungus does not kill the crowns or roots of the grass plants, and Red Thread will generally disappear in warmer summer weather.