Bacterial Streak of Smooth Bromegrass Caused by Xanthomonas campestris pv. cerealis (Hagborg 1942) Dye 1978

Abstract

In 1978, bacterial streak of smooth bromegrass caused by Xanthomonas campestris pv. cerealis (Hagborg 1942) Dye 1978 occurred in Hokkaido, Japan. The lesions on the leaves were at first water-soaked, dark-green spots limited by the veins and gradually became elongate in interveinal parenchyma to form streaks. Later the lesions became translucent black streaks. The surface of the streaks was often covered with milky droplets of bacterial exudate under humid conditions and with thin, transparent and dried films of exudates under dry conditions. Typical symptoms were produced on smooth bromegrass, mountain bromegrass, quack grass, barley, rye, wheat and oats, but not on orchardgrass, timothy or rice by artificial inoculation. The bacteriological characteristics of the pathogen were determined: Cells were non-spore-forming rods with a single flagellum, Gram-negative and aerobic. Yellow pigment and slime were produced on nutrient glucose agar. Catalase and lecithinase reactions were positive, but Kovacs' oxidase, urease and tyrosinase were negative. Glucose was oxidatively metabolized. H₂S and ammonia were produced, but not 2-ketogluconate, indole or acetoin. Aesculin, Tween-80 and starch were hydrolysed, but not margarine or sodium hippurate. Gelatin was liquefied, and nitrate was not reduced. Growth on nutrient agar was inhibited by 0.1% TTC. Asparagine was inadequate as a sole source of carbon and nitrogen. Acid was produced from arabinose, xylose, glucose, fructose, galactose, mannose, sucrose, glycerol, cellobiose and trehalose, but not from rhamnose, maltose, lactose, raffinose, inulin, salicin, mannitol, sorbitol, adonitol, dulcitol or inocitol. Acetate, citrate, malate, succinate and lactate were utilized but not benzoate, oxalate or tartrate.