DISEASE ALERT | GRAY LEAF SPOT
Kate Entwistle The Turf Disease Centre
GRAY LEAF SPOT ON PERENNIAL RYEGRASS The first known UK case of Gray Leaf Spot disease on perennial ryegrass turf signals the arrival in Britain of potentially the most damaging fungal disease for this grass variety – and it’s a problem that can be extremely difficult to control
22 GROUNDS MANAGEMENT | OCTOBER 2020
AS A DISEASE of amenity turf, Gray Leaf Spot initially developed as a problem on warm-season turf grasses (notably St Augustine grass, Stenotaphrum secundatum) in the USA but, in the early 1990s, it became a serious problem in Lolium perenne perennial ryegrass and tall fescue turf being maintained in sports facilities. The disease then began to appear in Europe and has, over the past 15 to 20 years, progressed through much of mainland Europe – most notably Spain, Portugal, France, Germany, Austria and Switzerland. In August 2020, however, The Turf Disease Centre confirmed the
development of Gray Leaf Spot disease in a UK sample of perennial ryegrass turf, with spores of the causal fungus abundant in the symptomatic plants. This is the first known occurrence of the disease in UK perennial ryegrass and the importance of this outbreak should not be underestimated. This is potentially the most damaging fungal disease that can develop on stands of perennial ryegrass turf and the disease can be extremely difficult to control.
Causes and signs Gray Leaf Spot disease is caused by the fungus Pyricularia grisea