Most turf diseases are more troublesome on fine, closely mown turf, such as golf and bowling greens, than on a garden lawn. However, red thread (Laetisaria fuciformis) is an exception as it can prove quite troublesome on most types of turf. However in most cases it is not as serious as some other lawn diseases (Fusarium, Take-all, Anthracnose) and the turf will regain full health with good turf management practices.
Although it can be problematic at various times of the year, it predominantly infects the grass during the summer and autumn months. Although many species of grass can suffer from red thread, fescue and ryegrass are particularly susceptible to this disease.
Identification of Red Thread
As with any lawn pest and disease, it is important to be vigilant and check the lawn on a regular basis. Look out for irregular patches of pale brown or bleached leaves. Fescue and ryegrass are particularly susceptible to Red thread. Initially these patches are 20-30mm in diameter, as the disease progresses they can increase to 350mm in diameter. During periods of moist, damp weather conditions, red needle like strands or threads can be observed on the leaves of the infected grass plants.
Causes of Red Thread
Red thread can occur at any time of the year, but 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 control of Red Thread
- It is important the turf receives adequate nutrition, particularly nitrogen, (however, excess 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 red thread.
- Remove grass clippings when mowing the lawn. Remove early morning dew to help promote a dry surface.
- Relieving soil compaction to improve the surface drainage on the lawn by aerating, will help prevent this disease.
- If possible cut back any over hanging tree branches and remove excess vegetation to improve air flow and increase the amount of available sun light.
The above will help keep the turf surface drier and reduce the risk of an outbreak of red thread.
Chemical control of Red Thread
As red thread rarely kills the grass in all but a few severe cases, chemical control using fungicides, is rarely required. However effective fungicides are really only available for turf professionals, such as golf green-keepers, groundsmen and lawn care specials who have the relevant qualifications.
Amateur gardeners will have to employ the cultural methods of prevention and control, which can prove very effective against this disease.