Pathogen identification of Kadsura coccinea anthracnose and indoor toxicity measurement of fungicides
[Objective]The study aimed to identify the species of the pathogen of Kadsura coccinea(Lem.)A.C.Smith,screen out suitable fungicides,and provide theoretical basis for the identification and field prevention of the pathogen of K.coccinea.[Method]The pathogen of K.coccinea leaves collected from Yunfu,Guangdong province were isolated by tissue block separation method,which was determined based on Koch's postulates and was identified by morphology and molecular biology.The mycelial growth rate method was used for biological tes-ting,as well as indoor toxicity of different fungicides to K.coccinea.[Result]By isolating and purifying the diseased leaves,a total of 6 strains were obtained.And representative strain A1 was selected for morphological identification and ITS sequence analysis.The pathogen of K.coccinea was identified as Colletotrichum sp..Through biological testing of strain A1,it was determined that the most suitable growth me-dium was PDA medium,the most suitable temperature for mycelial growth was 28 ℃,the lethal temperature was 53 ℃ for 10 minutes,the optimal pH for mycelium growth was 6.0,the optimal lighting conditions were continuous darkness,the optimal carbon and nitrogen sources for this mycelium were maltose and yeast powder.Among the four tested fungicides of thiram,bromoxynil,carbendazim and azoxystrobin,carbendazim had the best inhibitory effect,with an EC50 value of 0.14 μg/mL.Followed by thiram and bromoxynil,with EC50values of 55.26 and 55.32 μg/mL,respectively,indicating that they had better inhibitory that effect.The EC50 value of azoxystrobin was 791.95μg/mL,with a range of 100-1000 μg/mL,and the antibacterial effect was not significant.[Conclusion]The results show that Colletotri-chum sp.is the pathogen of Kadsura coccinea collected from Yunfu,Guangdong province.Carbendazim,thiram and bromoxynil could be used as candidate field control agents for the pathogen of K.coccinea.
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