Identification And Biological Characteristics Of Chinese Glossy Privet Anthracnose Pathogen And Screening Of Fungicides

Ligustrum lucidum Ait is an important ornamental garden plant in China,and anthracnose of Ligustrum lucidum is one of the important diseases on Ligustrum lucidum.In this paper,five strains were isolated from anthracnose leaves of Ligustrum lucidum collected in Hefei,Anhui Province,and the pathogenic bacteria were identified by morphological and molecular biological methods,and their pathogenicity was determined by robert koch’s rule.Study its biological characteristics by biological and physiological and biochemical methods;The virulence of fungicides was determined by mycelium growth rate method.The main results are as follows:1.Isolation and identification of pathogenic bacteriaThe pathogen was isolated by tissue isolation.After 5 days of culture,the colony was milky white,and 9 days later,the pathogen produced more melanin,and the whole colony was black.The hyphae are colorless and septate,the conidia are single spore,colorless,2-3 oil droplets,oval or sausage-shaped,and the size is 7.18-9.23×6.56-8.27.Cluster analysis of internal transcribed spacer,ITS)genes of pathogenic bacteria showed that the isolated pathogenic bacteria were in the same branch with Colletotrichum gloeosporioides.Combined with morphological and molecular biological identification and robert koch’s rule verification,Colletotrichum gloeosporioides was the pathogenic bacteria of the disease.2.Biological characteristics of Colletotrichum gloeosporioides in Ligustrum lucidumThe results showed that PDA medium was the most suitable medium for mycelium growth of anthrax pathogen of Ligustrum lucidum,and Czapek medium was the most suitable medium for sporulation.It grows well at 20 ℃-30 ℃.The optimum temperature for growth and sporulation of pathogenic bacteria is 28℃ and the lethal temperature is 50℃ for 10 min.The optimum p H for growth is 7,and when p H is 6,the pathogen reaches the maximum sporulation.Maltose is the best carbon source for growth,and urea is the best nitrogen source for growth.3.Screening of effective fungicides of Ligustrum lucidum anthracnoseThe inhibition effects of carbendazim,difenoconazole,pyraclostrobin,tebuconazole and thifluzamide on mycelium growth and conidia germination of Ligustrum lucidum were determined by indoor toxicity test.The results showed that carbendazim had the best inhibitory effect on mycelial growth,with EC50 of 1.7951g/ml,and difenoconazole had the best inhibitory effect on conidia germination,with EC50 of 0.9643 μg/ml,and difenoconazole had better inhibitory effects on mycelial growth and conidia germination.