檬果果斑病之研究(I)病徵及病原菌

Abstract

檬果果斑病為臺灣檬果之新病害，民國五十八年發見以來，為害日趨嚴重，一般認為抗病力甚強之菜檨子（本地種），枝葉亦嚴重受害。果實之病斑發生在皮目上，初期有流膠及三角形裂縫，漸擴展呈黑褐色之星形，同時病斑突起，細菌分泌物沿果皮流下。葉部病斑與1948年Patel氏等在印度發現者近似。本病亦在葉柄及幼枝發生。 病原經試驗結果證實為一細菌性病害。病原體為桿狀，大小約0.4~0.6×0.8~1.7μ，單胞或呈短鏈狀，Gram陰性，非抗酸性，無內生胞子及莢膜，具活動性之單極單鞭毛，在馬鈴薯葡萄糖培養基平板上為圓形，白色或乳白色，中高、全緣之菌落，生長良好。肉汁培養液中勻，有微量粘性沈澱，表面有輪環。在USchisky氏及Cohn氏液均不生長。本病原菌之生長適溫為攝氏28~30度，氫離子在pH7.0時生長最好。在Glucose, Saccharose, Starch, Trehalose, Dextrin, D-Galactose, D-Xylose, Raffinose, Grycerin, D-Mannitol及Sorbitol培養基中產生酸，但不產生氣體，能水解澱粉和酪素。除Fs 33外，不能使硝酸鹽還原。能使白明膠液化，石蕊還原，不產生吲哚，產生硫化氫和觸釀之好氣性桿狀菌。據試驗結果證實，本病原之生理及形態與Patel氏等(1948)發現之Pseudomonas mangiterae-indicae近似，惟不能為害Cashewnut。 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 ex-udate flows downward. The lesions are 1-5mm 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 falled down, sometimes the tender branch may infected. The causal bacterium was isolated, it is a aerobic bacterium, rod-shaped 0.4-06 × 0.8-1.7μ in size, Single or short chain, not acid-fast, without endospore, motile by monot-richous 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.