檬果果斑病之研究 I.病徵及病原菌

Abstract

The fruit spot of Mango, a new disease in Taiwan was found at Yu-Ching in 1969, the same disease had reported by Patel in India in 1948. The disease is characterized by appearing crack with clearing exudate at lenticels on fruits about at the 10th day after infection, then turning to deep brown stellate spots with raised and heavy bacterial exudate flows downward. The lesions are 1-5 mm in diameter, 2-3 mm in depth. The leaf lesions are angular, dark brown, water-soaked areas from 1-4 mm in diameter with clearing margin, rough and raised later. In severely affected ones, the most of fruits and leaves are failed down, sometimes the tender branch may infected. The causal bacterium was isolated, it is a aerobic bacterium, rod-shaped 0.4-0.6×0.8-l.7μ in size, Single or short chain, not acid-fast, without endospore, motile by monotrichous flagellum. Potato-Dextrose Agar colony is circular, white to creamy white with entire margin, smooth, glistening, translucent. No growth in both Uschisky's solution and Cohn's. The temperature range for growth of the bacterium is 8-36℃, the optimum temperature being 28-30℃. The pH range for growth is 4.0-10.0, the optimum being 7.0. Starch and casein are hydrolyzed, nitrates are not reduced except Fs 33, gelatin is liquefied, Litmus is reduced, no indole is produced, hydrogen sulfide is produced. Acid but no gas is produced from glucose, saccharose, starch, Trehalose, Dsxtrin, D-Galactose, D-Xylose, Raffinose, Grycerin, D-Mannitol and Sorbitol, no acid and gas are produced from L-Arabinose, Lactose, Maltose, Inulin, L-Rhamnose, D-Mannose and Salicin. The causal bacterium affects Mangifera indica L. but does not infects Anacardiuinm occidentale L. (Cashew nut).