Bacterial Blight of Orchardgrass Caused by Xanthomonas translucens f. sp. hordei Hagborg

Abstract

In June of 1966, a new bacterial disease was found causing brownish streaks on the foliage of orchardgrass (Dactylis glomerutaL.) in Japan. The causal organism was identified as Xanthomonas translucens f. sp. hordei Hagborg, considering its bacteriological characters, symptom on the leaf-blade showing the characteristic translucency and pathogenic specialization. It is the first time that X. translucens has been found to attack orchardgrass naturally and some of wheatgrasses (Agropyronspp.) artificially.
The bacteriological characters of the pathogen are as follows: Cylindrical rods rounded at ends, Solitary or in pairs; 0.6×1.2-2.4μ in size, motile with a single flagellum; capsulate, Gram negative, no spores, aerobic. Superficial colonies, yellow, round, convex, smooth, shining, opaque, with entire margin. Liquefies gelatin slowly; digests milk slowly without coagulation; nitrates not reduced; hydrogen sulphide and ammonia produced, but not indol or acetoin; starch hydrolysed variable. Acid but no gass produced from arabinose, xylose, glucose, fructose, galactose, mannose, lactose, sucrose and glycerol: neither acid nor gas from rhamnose, maltose, raffinose, starch, inulin, dextrin, mannitol, sorbitol or salicin. Aesculin hydrolysed; oxidase-positive; lipolytic. According to Hugh-Leifson's method, acid produced aerobically from glucose. Optimum temperature 30°C.