Abstract:
Objective Pathogen and effective fungicides of the leaf spot disease on one of China’s top 10 famous teas, Duyun Maojian, were identified.
Method Diseased leaves were collected from the tea bushes at Hongmin Tea Garden in Duyun City to isolate and purify pathogen. Pathogenicity of the isolate was determined based on the Koch’s postulation prior to species identification by integrating morphological characteristics with multilocus phylogenetic analyses of the ITS, EF1-α, and RPB2 gene regions. In vitro inhibitory activities of 5 fungicides on the isolate were compared using the mycelial growth rate method.
Result Three morphologically identical strains were isolated from the symptomatic leaf tissues and confirmed to be the disease causing pathogen by the Koch pathogenicity protocol. The concatenated multilocus phylogenetic analyses showed the isolate to be in a clade with Alternaria alternata. The 5 fungicides all exhibited significant inhibitory activity against the pathogen with the 40% difenoconazole suspension concentrate showing an EC50 of 1.4130μg·mL−1 being the strongest. The next strongest fungicide was the 45% prochloraz emulsion in water with an EC50 of 2.2467μg·mL−1.
Conclusion For the first time, A. alternata was identified to be the pathogen that caused the leaf spot disease in Maojian tea plants at Duyun City and in Guizhou Province. The in vitro evaluation on 5 fungicides indicated that difenoconazole and prochloraz could be effective for the disease control.
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