‘芽黄’红瑞木枝干溃疡病病原菌的鉴定及药剂防治

摘要

Trunk canker is a severe disease of Cornus alba ‘Bud's Yellow’ in Shanghai.The causal pathogen was identified as Pestalotiopsis sp.through isolation,pathogenicity determination and morphological identification.Phylogenetic analysis based on the comparison of rDNA-ITS sequences showed that this pathogen belonged to the clade possessing versicolorous median cells,which was consistent with the morphological result.The half maximal effective concentrations (EC50) of five fungicides were 0.639-1.787 tμg/mL.Field trials showed that the control efficacy of 25％ propiconazole emulsifiable concentrate and 25％ azoxystrobin suspension were above 80％ in early stage of the disease,while the control efficacies of all the four fungicides were less than 50％ in the following stage of disease development.%‘芽黄’红瑞木枝干溃疡病在上海发生严重.本研究通过病原菌分离,致病性测定和形态学特征观察,将引起此病害的病原菌鉴定为拟盘多毛孢属一种Pestalotiopsis sp..通过扩增病原菌的rDNA-ITS序列,构建系统发育树,其在系统发育树上与拟盘多毛孢属中分生孢子中间三个细胞异色的类群处于同一分支,此结果与形态学鉴定结果一致.5种杀菌剂室内药剂筛选结果表明,对Pestalotiopsis sp.的抑制中浓度(EC50)为0.639～1.787 μg/mL.4种杀菌剂室外药效试验结果表明,在发病初期,25％丙环唑乳油和25％嘧菌酯悬浮剂防治效果可达80％以上,当病害发展后,供试4种杀菌剂对病害的防治效果均小于50％.