喜树叶斑病病原菌鉴定及其防治药剂筛选.

[ Objective] The present paper aimed to identify the causal agents of Camptotheca acuminata leaf spot, and to test the inhibitory activity of different fungicides against the pathogen, so as to provide scientific evidence for the prevention and treatment of the leaf spot disease of C. acuminata. [ Method] The pathogen of the C. acuminata leaf spot was isolated by conventional tissue isolation method and subjected to pathogenicity test. Combining the morphology observation and rDNA-ITS sequence analysis, the pathogen was identified and the toxicity of 12 fungicides to the pathogen was determined by mycelial growth rate method.[ Result] A fungus was isolated from C. acuminata leaf spot in the Chinese Herb Garden of Guangxi Agricultural Vocational University, and the strain was named as XS-1. After pathogenicity test, morphological observation and molecular identification, it was confirmed that Corynespora cassiicola was the causal agent of the C. acuminate leaf spot, which is reported for the first time in China, and the disease was named as Corynespora leaf spot disease. The results of the inhibitory activity test showed that the selected 12 fungicides had a certain inhibitory effect on the growth of strain XS-1 mycelium. Among them, 20% difenoconazole and prochloraz ME had the strongest inhibitory effect with EC50 of 0.098 mg/L, followed by 20% penconazole EW, 50% carbendazim WP, 20% imazalil EW, 250 g/L propiconazole EC, 10% difenoconazole WG with EC50 of 0.3737, 0.4557, 0.4878, 0.5746 and 0.5956 mg/L, respectively.[ Conclusion] Based on pathogenicity test, morphology observation and rDNA-ITS sequence analysis, the pathogen causing C. acuminata leaf spot is identified as C. cassiicola. 20% difenoconazole and prochloraz ME, 20% penconazole EW, 50% carbendazim WP, 20% imazalil EW, 250 g/L propiconazole EC and 10% difenoconazole WG have strong inhibitory effect on the growth of strain XS-1 mycelium, and can be used as an important reference for the control of Corynespora leaf spot on C. acuminata in the field. [ABSTRACT FROM AUTHOR]