湖南新化多花黄精叶枯病病原鉴定及室内毒力测定

Identification and Laboratory Toxicity Test of the Pathogen of Leaf Blight of Polygonatum cyrtonema in Xinhua of Hunan Province

为明确湖南新化多花黄精叶枯病病原菌种类组成及其致病力情况,采用组织分离法对19份多花黄精叶片病样进行分离、培养和纯化,采用形态学和分子生物学方法对分离菌株进行鉴定,并通过离体叶片接种法对所获得的菌株进行致病力测定。结果表明:引起湖南省新化县多花黄精叶枯病的病原菌为间座壳属(Diaporthe)的Diaporthe hongkongensis、Diaporthe tulliensis和Diaporthe eres这3个种;其中Diaporthe hongkongensis的致病力最强,Diaporthe eres次之,Diaporthe tulliensis的致病力最弱。选取了5种常见药剂采用生长速率法对Diaporthe hongkongensis进行室内毒力测定。结果表明:5种供试药剂的EC_(50)值大小表现为25%嘧菌酯悬浮剂> 32.5%苯甲–嘧菌酯悬浮剂> 75%百菌清可湿性粉剂> 10%苯醚甲环唑水分散粒剂> 5%己唑醇悬浮剂,其中对该病菌毒力最强的杀菌剂为5%己唑醇悬浮剂,其EC_(50)值为8.932 mg/L。综上所述,湖南新化的多花黄精叶枯病是由间坐壳属真菌侵染引起的,5%己唑醇悬浮剂、10%苯醚甲环唑水分散粒剂对该病菌的杀菌效果较好,可作为防治药剂。

This study aims to clarify the pathogen composition of leaf blight of Polygonatum cyrtonema and their pathogenicities in Xinhua County of Hunan Province.Nineteen diseased leaf samples were isolated,cultured and purified by tissue separation method;the isolates were identified by morphological and molecular biological methods;and the pathogenicity of the isolates and their pathogenicity differences were determined by the inoculation method of in vitro leaves.The results showed that the pathogens were Diaporthe hongkongensis,Diaporthe tulliensis and Diaporthe eres of Diaporthe based on morphological characteristics and comparative analysis of gene sequences of 28S rDNA-ITS,β-tubulin and EF-1α.Among them,Diaporthe hongkongensis had the strongest pathogenicity,followed by Diaporthe eres,and Diaporthe tulliensis was the weakest.Thereafter 5 kinds of ordinary fungicides were selected for indoor toxicity test of Diaporthe hongkongensis by the growth rate method.The toxicity test result showed that EC_(50) values of the five tested agents ranked as azoxystrobin 25%SC>difenoconazole-azoxystrobin 32.5%SC>chlorothalonil 75%WP>difenoconazole 10%WG>hexaconazole 5%SC,among which hexaconazole 5%SC had the strongest toxicity to the pathogen,and its EC_(50) value was 8.932 mg/L.In sum,the leaf blight of Polygonatum cyrtonema in Xinhua County of Hunan Province is caused by infection of Diaporthe.Both hexaconazole 5%SC and difenoconazole 10%WG have good control effect on mycelial growth of the pathogen and can be used as control agents.