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2007—2010年从广西、广东两省(区)9个样区采集冬瓜、黄瓜疫病显症植株,经分离纯化鉴定共获得193株瓜类疫霉。采用菌丝块无伤接种法,将菌株接种冬瓜和黄瓜,测定、比较其对供试寄主植物的致病力及其寄主嗜好性。结果表明,病原群体对寄主植物冬瓜和黄瓜的致病力均存在明显分化现象,可分为强致病力、中等致病力及弱致病力3大类群;来自不同地区的瓜类疫霉对寄主植物冬瓜和黄瓜的致病力明显不同,多数样区以强致病力菌株占优势。瓜类疫霉种群中存在3种寄主嗜好型菌株,A型菌株对冬瓜和黄瓜均表现强致病力,与原始分离寄主无关;B型菌株仅对原始分离寄主冬瓜表现强致病力,而对黄瓜则表现为弱或中等致病力;C型菌株仅对原始分离寄主黄瓜表现强致病力,而对冬瓜则表现为弱或中等致病力。
From 2007 to 2010, 9 strains of wax gourd and cucumber disease were collected from 9 samples of Guangxi and Guangdong provinces (regions). 193 strains of melon Phytophthora melon were obtained through isolation and purification. Using mycelium non-invasive inoculation method, the strain was inoculated with melon and cucumber, and the pathogenicity and host preference of the tested host plants were compared. The results showed that the pathogens showed obvious differentiation on the pathogenicity of the host plants, melon and cucumber, and could be divided into three groups: virulent, moderate pathogenic and weak pathogenicity. Phytophthora meliloti The pathogenicity of the host plant wax gourd and cucumber significantly different, the majority of samples with strong virulent strains prevail. There were three kinds of host-preferred strains in Phytophthora melon populations. Type A strains showed strong pathogenicity to both melon and cucumber, which had no relationship with the original isolated host. Type B strains showed strong virulence only to the original isolated melon, Cucumber showed weak or moderate pathogenicity; C type strains showed strong virulence only to the original isolated host cucumber, but showed weak or moderate pathogenicity to the gourd.