Pathogens occurring on ten varieties of ryegrass at Rothamsted in 1973-1974

Six varieties oi Loliumperenne, three of L. multiflorum and one hybrid (L. multiflorum × L. perenne) were assessed for diseases over two harvest years. Crown rust (Puccinia coronata) and mildew (Erysiphe graminis) occurred on some varieties in 1973. Leaf spotting (Drechslera spp.) was common, but slight on most varieties, in both years. Ryegrass mosaic virus (RMV) and its mite vector, Abacarus hystrix were present on all varieties in the second year. The relative susceptibility of varieties to RMV was similar in the field and in glasshouse tests.