【作者】 王惠哲；

【导师】 董金皋；

【作者基本信息】 河北农业大学 ， 植物病理学， 2003， 硕士

【摘要】 针对近年来各地黄瓜根腐病普遍发生并逐年加重的现状，本文以黄瓜根腐病为研究对象，进行了致病病原菌的分离、鉴定、生物学特性研究以及室内药剂筛选等试验。为明确黄瓜根腐病致病病原菌的种类，作者于1999～2002年从天津市及周边地区共采集、分离88个菌株。从黄瓜病株根部及茎基部分离到3类病原分离物。经对其培养性状调查、形态观察及其接种鉴定表明，这几种分离物分别为甜瓜疫霉（Phytophthora melonis）、尖孢镰刀菌（Fusarium oxysporum）和茄病镰刀菌（Fusarium solani）。致病性测定结果表明，甜瓜疫霉是引致天津市区及郊区黄瓜根腐病的致病菌，而后两种镰刀菌可能加重该病的发生。试验还表明，目前的黄瓜主栽品种大都不抗甜瓜疫霉，而有抗镰刀菌的品种。因此，当前黄瓜生产所面临的亟待解决的问题就是抗甜瓜疫霉菌品种的选育。 本文对分离出的每类病菌随机选取菌株进行了生物学特性研究。结果表明，甜瓜疫霉生长发育最适温度介于25～35℃，最佳温度为32℃，致死温度为45℃，10分钟；尖孢镰刀菌生长适温为20～32℃，最佳温度为28℃左右，37℃条件下停止生长；茄病镰刀菌生长适温为25～35℃，最佳温度为30℃左右，37℃仍可以生长。根据变温培养试验可知，供试2种镰刀菌在28～30℃时生长较为合适，茄病镰刀菌比尖孢镰刀菌生长适温偏高。两种镰刀菌的生长最适pH值为6～8；不同含量氮、磷、钾营养元素对镰刀菌菌丝生长影响不大。 通过室内平板法测定了甜瓜疫霉23个菌株对甲霜灵的敏感性，结果表明，天津及周边地区的黄瓜根腐病致病菌——甜瓜疫霉对甲霜灵的敏感性差异不大，未发现高度抗性菌株。同时测定了其他9种杀菌剂对甜瓜疫霉的毒力，结果表明，甲霜灵、甲霜灵-锰锌和氟吗啉对甜瓜疫霉的毒力最强，其EC₅₀分别为0.115μg·mL^-1，0.905μg·mL^-1和2.202μg·mL^-1；阿米西达、（口恶）霜锰锌、代森锰锌和霜脲氰锰锌对甜瓜疫霉毒力次之，其对P025-1的EC₅₀分别为18.952μg·mL^-1，22.761μg·mL^-1，29.161μg·mL^-1和49.552μg·mL^-1；（口恶）霉灵和霜霉威对甜瓜疫霉毒力最差，其对P025-1的EC₅₀分别为133.785μg·mL^-1和3814.549μg·mL^-1。更多还原

【Abstract】 Recently Cucumber root rot, a kind of soil-borne disease, becomes more and more serious in many cucumber-planting areas. The disease could result in cucumber root rot, and directly affected the production and the yield of cucumber. To elucidate the causal agents and occurrence of the disease, 88 isolates of the possible pathogen were purified from diseased cucumber plants in Tianjin city suburbs and rural areas during 1999 to 2002. Three kinds of fungi, Phytophthora melonis, Fusarium oxysporum and F. solani were identified from the isolates. The pathogenicity of the fungi was tested in greenhouse. The results showed that Phytophthora melonis was the pathogen, but Fusarium oxysporun and F. solani could help the occurrence of the disease and make it more serious. The test also had shown that there were no cucumber cultivars resistant to Phytophthora melonis, however some cultivars resistant to the two Fusarium fungi were found in the test.The biological characteristic of the three fungi were studied in the laboratory. The proper temperature for the growth of P. melonis, F. oxysporum and F. solani was 25 ~ 35 , 20~32 and 25~35 respectively. The best temperature for the growth of the three fungi was 32 , 28 and30 respectively. The suitable pH value range for the two Fusarium growth was pH6~8. Different content of nitrogen, phosphorus and potassium in the medium had little effect on the growth of the two Fusarium pathogens.The sensitivity of P. melonis to metalaxyl was tested in laboratory, and the results indicated that all the isolates tested were sensitive to the fungicide. The virulence of other 9 fungicides to P.melonis also was identified and the results had shown that 25% WP Metalaxyl, 58% WP Metalaxyl -MZ and 60% WP Flumorph were more effective to the fungus, and the EC50 were 0.115 g -mL-1, 0.905 g -mL-1 and 2.202 g -mL-1 respectively. Amistar, Sandofan, Mancozeb and Cymoxanil Mancozeb had less virulence to P. melonis, but Hymexazol and Prompamocarb hydrochloride had little effect.更多还原