Foliar fungal diseases of perennial ryegrass at 16 sites in England and Wales

The incidence and severity of infection by fungal diseases was recorded on youngest fully expanded leaves of perennial ryegrass (Lolium perenne) in May and/or September from 1985 to 1987 at 16 sites in England and Wales. Leaves were collected from swards of a single cultivar, Melle, given the same management at each site. Drechslera spp. were present at all sites, and infection exceeded 10% of leaves at eight sites. Rhynchosporium spp. were present at 15 sites but infection exceeded 10% of leaves at only two sites in southern England. Powdery mildew (Erysiphe graminis) was present at 10 sites and infection exceeded 20% of leaves at four sites. Crown rust (Puccinia coronata) was present at six sites, mainly in central and southern England, and infection exceeded 10% of leaves at two sites. Mildew and rust were present only in September, Drechslera was more frequent in September than May and Rhynchosporium was about equally frequent in May and September. The area of leaf damaged by Rhynchosporium ranged from 5 to 23% overall; the range for the other diseases was 1–3%.