Abstract
In May and June, 1984, a new bacterial disease was observed on greenhouse-planted cucumber in Shizuoka Prefecture. The disease appeared on the leaves as a pin-point, water-soaked lesion which enlarged to form a brown, necrotic, angular spot. There was no tendency of the lesions to tear out. The causal bacterium was a gram-negative, aerobic rod with single polar flagellum. It formed a yellow slimy colony, liquefied gelatin, produced hydrogen sulfide and hydrolyzed starch. It neither reduced nitrate to nitrite, nor produced arginine dihydrolase or lecithinase. Acid was produced from glucose, sucrose, lactose, starch, dextrin and glycogen, but not from mannitol, ribose or dulcitol. By inoculation, the causal bacterium showed strong pathogenicity on cucumber, pumpkin and watermelon, but not on cabbage, bean or tomato. From these results, the causal bacterium was identified as Xanthomonas campestris pv. cucurbitae (Bryan 1926) Dye 1978. This is the first report of bacterial brown spot disease of cucumber in Japan.
