青脆李褐腐病原菌鉴定及其防治药剂的筛选

Identification of pathogen causing brown rot of green crispy plum and screen of pesticide for protection

[目的]明确青脆李褐腐病病原菌、分析病原菌致病力并筛选防治药剂,为青脆李褐腐病防控提供理论依据。[方法]按照柯赫氏法则分离纯化病原菌,通过形态学观察,多基因位点联合分析鉴定病原菌,通过致病性测定及聚类分析研究病原菌致病力差异。[结果]分离获得青脆李褐腐病原菌8株,形态学鉴定显示8株菌为Monilinia spp.,构建系统发育树鉴定8株菌均为Monilinia fructicola;致病力测定显示,病原菌株病斑直径统计学差异显著,接种LZ-7果实病斑直径最小(16.950 0±1.102 8 mm),接种LZ-13果实病斑直径最大(31.405 0±1.767 5 mm);聚类分析将8株病原菌致病力分为3组:LZ-7为弱致病力菌株、LZ-2/8/3/16/14为中致病力菌株、LZ10/13为强致病力菌株。选取致病力最强菌株LZ-13进行化学防治药剂筛选,按照EC_(50)由低到高排依次为代森锰锌<戊唑醇<甲基硫菌灵<苯甲·中生<腐霉利。[结论]青脆李褐腐病病原菌为Monilinia fructicola,同种Monilinia fructicola病原菌不同菌株间存在致病力差异,代森锰锌及戊唑醇室内毒力EC_(50)均小于1μg·mL^(-1)。

[Objective]Identify and assess the virulence of pathogens causing brown rot of green crisp plum,screen pesticide for protection,so as to provide a theoretical basis for the fungicide control of brown rot of green crisp plum.[Method]The pathogens were isolated and purified according to Koch's rule.The pathogens were identified through morphological observation,combined multi-locus analysis,and their pathogenicity differences were studied using virulence determination and cluster analysis.[Result]Eight pathogens of green crisp plum brown rot were isolated.Morphological identification showed that eight strains were Monilinia spp.Phylogenetic tree showed that all the eight strains were Monilinia fructicola.Virulence analyze showed that there were significant differences in lesion size among pathogenic strains.The brown rot lesion diameter was smallest(16.950 0±1.102 8 mm) in fruits inoculated with strain LZ-7 and largest(31.405 0±1.767 5 mm) in fruits inoculated with strain LZ-13.Cluster analysis grouped the eight strains into three virulence categories:LZ-7 was classified as a weak virulence group,LZ-2/8/3/16/14 were classified as moderate virulence groups,and LZ-10/13 were classified as high virulence groups.The most pathogenic strain LZ-13 was selected for screening fungicide control agents.Based on EC_(50) values,the efficacy order from highest to lowest was mancozeb<tebuconazole<thiabendazole<difenoconazole·zhongshengmycin<putrescine.[Conclusion]This study identified the pathogen causing brown rot in green crisp plums as Monilinia fructicola,and significant differences in virulence were observed among the strains.Laboratory toxicity tests showed that the EC_(50) values for mancozeb and tebuconazole were less than 1 μg·mL~(-1).