In an examination of the susceptibility of 27 fodder grass varieties cultivated in the GDR to 14 races of barley mildew, 9 races of wheat mildew and 1 population of rye mildew no infections were obtained. Since the races used represented the whole range of pathogenicity of the known races of cereal mildew, it may be assumed that under natural conditions cereal mildew does not cause any infection in the examined varieties of forage grasses.