DOWNY MILDEW OF DACTYLIS GLOMERATA CAUSED BY SCLEROPHTHORA CRYOPHILA
Keyword(s):
A disease of orchard grass (Dactylis glomerata L.) caused by a downy mildew, Sclerophthora cryophila n. sp., was first found in Saanichton, near Victoria, B.C., in 1948. The symptoms appear on the leaves as light brown, oval-elongate to irregular areas, and as interveinal and marginal streaks. The inflorescences are occasionally affected. Zoospores are liberated from sporangia at 1 °C., but the most favorable temperature for their emergence is between 4° and 9 °C. The disease is considered of economic importance, particularly where orchard grass is grown for seed. Control involves the use of seed from disease-free crops and the application of fungicidal sprays or dusts during late autumn and late winter.