兰花根腐病病原菌分离鉴定及室内药剂筛选

Isolation and Identification of Pathogen of Orchid Root Rot and Screening of Laboratory Agents

【目的】为探究引发兰花根腐病的病原菌种类,及室内不同化学药剂与生物菌剂对兰花根腐病的防治效果。【方法】研究以三明市农业科学研究院兰花种质圃的3株墨兰病株为样本,采用组织分离技术、菌落形态观察、分子生物学鉴定以及柯赫氏法则的病原菌致病性检测分离鉴定病原菌。同时,测定平板抑制率分析7种化学药剂和2种生物菌剂对分离菌株的抑制效果。【结果】从典型的兰花根腐病病株分离纯化后获得3株培养性状一致的菌株,其菌落形状均为圆形,正面灰白色,边缘整齐呈放射状,气生菌丝白色或灰白,稀薄棉絮状,背面呈淡黄色或紫红色;ITS、cal分子标记序列比对均与NCBI数据库中尖孢镰刀菌(登入号为:ON960618.1)的序列同源性为100%,系统进化表明二者在遗传上紧密相关,致病性测定结果表明其发病症状与田间表现一致,符合柯赫氏法则,综合形态学与遗传学特征,鉴定出兰花根腐病病原菌为尖孢镰刀菌。室内药剂筛选表明,3种化学药剂多菌灵、代森锰锌、喹啉酮和2种生物菌剂哈茨木霉菌、枯草芽孢杆菌对分离菌株的抑制效果较弱或者无效果;4种化学药剂精甲·恶霉灵、精甲·嘧菌酯、克菌丹、咪鲜胺锰盐对分离菌株的抑制效果较好,抑菌效果依次为咪鲜胺锰盐>精甲·恶霉灵>精甲·嘧菌酯>克菌丹。【结论】本研究分离鉴定出一种引发兰花根腐病的病原菌尖孢镰刀菌Fusarium oxysporum,筛选出对兰花根腐病室内防治效果最佳的药剂为咪鲜胺锰盐,然后依次为精甲·恶霉灵、精甲·嘧菌酯、克菌丹,为兰花根腐病的防治提供了技术参考。

【Objective】To explore the species of pathogen causing orchid root rot and the control effect of different laboratory chemicals and bioagents on orchid root rot.【Method】Three infected Cymbidium sinense strains from the orchid germplasm nursery of Sanming Academy of Agricultural Sciences were taken as samples in the study.The pathogen were isolated and identified by tissue separation,colony morphology observation,molecular biological identification,and pathogenicity detection by Koch's rule.At the same time,the inhibition rate of the plate was determined to analyze the inhibitory effect of seven chemical agents and two bioagents on the isolated strains.【Result】The results showed that three strains with the same culture characteristics were obtained from the typical orchid root rot strains,which were gray and white with round colonies and neat and radial edges.The air mycelium was white or gray like thin cotton wool,the back of the colony was light yellow or purple red.The sequences of ITS and cal were 100%homology with those of Fusarium oxysporium(login number:ON960618.1)in NCBI database.Phylogenetic evolution showed that the two pathogens were closely related genetically,and pathogenicity test results showed that three symptoms were consistent with field manifestations accordance fitting Koch’s rule.Combining morphological and genetic characteristics,the pathogen of orchid root rot was identified as Fusarium oxysporum.The results showed that three chemicals including carbendazim,mancozeb and oxine-copper,and two bioagents including Trichoderma harzianum and Bacillus subtilis,had weak or no inhibitory effect on the isolated strains.Four chemicals including metalaxyl-M·hymexazol,metalaxyl-M·azoxystrobin,captan,and prochloraz-manganese chloride complex had strong inhibitory effect on the isolated strains.The sequence of inhibitory effect were prochloraz-manganese chloride complex>metalaxyl-M·hymexazol>metalaxyl-M·azoxystrobin>captan.【Conclusion】A pathogen of orchid root rot was identified as Fusarium oxysporum.The best fungicide for controlling orchid root rot disease in laboratory was pokraman,and followed by propineb-hymexazol mixture,propineb-azoxystrobin mixture,captan,which provided a technical reference for the control of orchid root rot.