广西上思县桉树青枯病原菌致病性的研究

目的]为林业生产防治青枯病提供理论指导。方法]从广西上思县2种发病症状的桉树病株根上收集青枯病病原菌,按柯赫原则研究其致病性。结果]2种症状的90%以上分离物的菌落形态完全相同,分离培养证实均是与自然界完全相同的青枯病菌。人工培养基上培养的慢性型青枯病菌部分菌株发生变异,致病性减弱甚至丧失,急性型青枯病菌的菌株致病性未减弱。接种试验表明,急性型症状病株上分离所得青枯病病原菌致病力强于慢性型症状的病原菌,桉树苗木死亡率高,发病时间早,发病程度也有一定差异。结论]2种症状分离到的病原菌都为青枯病菌,均有明显致病性,急性型病原菌致病力强于慢性型,筛选出4个致病力较强的菌株。

Studies on the Pathogenicity of Eucalyptus bacterial Wilt Pathogens in Shangsi County of Guangxi Province

Objective] The study aimed to provide theoretical guidance for controlling bacterial wilt in forestry production.Method]Eucalyptus bacterial wilt pathogens were collected from roots of diseased eucalyptus plants with 2 kinds of disease symptoms in Shangsi County Guangxi Province,and their pathogenicities were studied according to Kohn's rule.Result] The colony morphologies of more than 90% of isolates from 2 kinds of symptoms were completely same,and isolation and culture experiments validated that they were identical with natural bacterial wilt pathogens.The mutation occurred on part bacterial strains of chronic bacterial wilt pathogens cultured on artificial medium,with pathogenicity weakening and even losing.The pathogenocity of bacterial strain of emergent bacterial wilt pathogens didn't weaken.Inoculation experiment showed that the pathogenocity of bacterial wilt pathogens isolated from diseased plant with emergent symptom was stronger than that of pathogens from chronic symptom.The seedlings mortality of Eucalyptus was high and the disease occurrence was early with the diseased degrees with some difference.Conclusion] The pathogens isolated from both the 2 symptoms were pathogens of bacterial wilt and had obvious pathogenicity. The pathogenicity of emergent pathogens was stronger than that of chronic pathogens and 4 bacterial strains with stronger pathogenocity were selected out.