Red Thread Lawn Disease

Unlike many other lawn and turf diseases red hhread (Laetisaria fuciformis) is not limited to closely mown luxury lawns. It can infect all types of lawns and turf. However in almost all cases it is not as serious as some other lawn diseases and the turf will regain health with good management practices.


Although it can be a problematic at various times of the year, it is predominantly seen during the summer and autumn months. Although many species of grass can suffer from red thread,  fescue and rye grass are particularly susceptible to this lawn disease.

Identification of red thread

It is important to be vigilant and look out for irregular patches of pale brown or bleached leaves. Fescue and ryegrass and are particulary susceptible to Red thread. Initially these patches are 20-30mm in diameter, later increasing to 350mm across, as the disease takes hold. During periods of moist and damp weather conditions, red needle like strands or threads can be seen on the leaves of the infected plants.

Causes of Red Thread

Red thread can occur at any time of the year, it is particularly troublesome in the summer and autumn, during warm moist conditions on lawns suffering from the following symptoms:

• Soil compaction due to lack or an absence of  lawn aeration.
• Areas of the lawn that suffer from shade are prone to an attack from this disease.
• A deficiency of nitrogen is a contributory factor to an outbreak of Red Thread. (however, do not apply large amounts of nitrogen too late in the season as this can cause Fusarium patch disease).

Prevention and cure of Red Thread

• Pay attention to maintaining adequate turf nutrition, particularly nitrogen levels, (however high levels of nitrogen should not be applied too late in the summer as it could lead to Fusarium patch disease.
• If Red thread is a perennial problem over seed with a different species of grass. Alternatively choose fescue and rye grass cultivar's that are resistant to this disease.
• Box off grass clippings when mowing the lawn. Remove early morning dews to help keep the grass leaves dry.
• Relieving soil compaction to improve the surface drainage on the lawn by aeration will help reduce red thread.
• If possible prune tree branches back and remove vegetation to improve air flow and increase the amount of sun light. These actions will help keep the surface drier and reduce the risk of Red Thread.

Chemical control of Red Thread

As this disease rarely kills the grass in all but a few severe cases, chemical control using fungicides is very seldom needed. However effective fungicides are really only available for turf professionals such as golf green keepers and groundsmen. For amateur gardeners the choice is very limited.