Identification,Biological Characterization,and Fungicide Screening of Pathogen Causing Leaf Spot Disease of Osmanthus fragrans(Thunb.)Lour.
[Objective]Leaf spot disease of Osmanthus fragrans seriously affects its ornamental value.This study aims to identify its pathogen and screen fungicides for controlling the disease.[Method]Spotted leave samples of O.fragrans were collected from Jinshan Park in Fuzhou and sample section was examined under a microscope.Fungal strains were obtained by tissue isolation method,and Koch's postulates were used to confirm the pathogenicity of the obtained strains.The strain was identified to species level though morphological characteristics and phylogenetic analysis of multilocus sequences(ITS,TUB,TEF,CAL and HIS).On this basis,the biological characteristics of the strain were determined.The toxic effects of four fungicides against pathogen were evaluated in vitro.[Result]]The strain FZ-GH-1 was clarified as the pathogen of leaf spot disease of O.fragrans,and was identified as Diaporthe grandiflori.The mycelial growth rate of FZ-GH-1 was fastest under 12-hour light/dark alternation and complete darkness conditions,with the optimal growth temperature being 24-28℃,optimal pH 5.0,optimal carbon source being glucose,and optimal nitrogen source being sodium nitrate and peptone.Of the tested fungicides,the EC50 of 70%thiophanate-methyl wettable powder and 450 g/L prochloraz aqueous emulsion on the growth of FZ-GH-1 mycelia was 0.108 mg/L and 0.053 mg/L,respectively,which was significantly lower than that of 30%mancozeb wettable powder and 20%triazolone emulsion.[Conclusion]This study confirmed D.grandiflori as the pathogen of leaf spot disease of O.fragrans,and thiophanate-methyl and prochloraz had strong inhibition effects on this fungus.The findings of this study provided a theoretical basis for investigating the pathogenesis and chemical control of leaf spot disease of O.fragrans in future research.
国家科技期刊平台
NSTL
万方数据
