Red Thread

Disease Background

Laetisaria fuciformis

Red thread is a fungal disease, which affects most cool season grasses, particularly perennial ryegrass (Lolium perenne) and red fescues (Festuca rubra spp.). Red thread is most prevalent during mild, humid conditions, which means it can be found active almost all year round in the UK. Symptoms are usually seen under conditions of low fertility, although an increase in activity is being recorded in turf which receives adequate nutrition. The severity of the infection will depend upon environmental influences and the susceptibility of the grass plant (stress factors or improved tolerance).


The significance of disease tolerance in grass breeding

There are significant differences in tolerance to red thread between individual cultivars within a species. Cultivar selections from the breeding programme are deliberately infected with red thread, both in the laboratory climate rooms and in field trials. In addition, red thread is also allowed to occur naturally in field trials in order to have a comprehensive picture of a particular cultivar’s tolerance. Graph 1 shows the tolerance of cultivars of perennial ryegrass (Lolium perenne); Graph 2 shows the tolerance of cultivars slender creeping red fescue (Festuca rubra trichophylla) and Chewings fescue (Festuca rubra commutata).