Abstract: During summer and autumn, serious new twig wilting occurs on a large scale in ‘Jiaming No. 1' tea gardens of Ruian City, Wenzhou, Zhejiang Province, China. The disease initially appears as irregular brown spots on the twigs, which later spread to shoots and leaves, causing the tea shoots to wilt and the leaves to curl and shrink, and eventually the whole branch to die. In this study, a strain was isolated and purified using the tissue isolation method. Combining the morphological characteristics with the phylogenetic analyses based on the sequences of the internal transcribed spacer regions (ITS), β-tubulin (TUB2), and the translation elongation factor1 alpha (TEF1-α), the isolated strain was identified as Botryosphaeria fusispora. Laboratory pathogenicity tests show that B. fusispora was the pathogen causing the twig wilting disease present on ‘Jiaming No. 1'. These results indicate that B. fusispora can be a new record species causing twig wilting on tea plants. In addition, mycelial growth inhibition tests were conducted to examine the sensitivity of the pathogen to three commercial fungicides, including chlorothalonil, thiophanate-methyl and pyraclostrobin. Among the tested fungicides, thiophanate-methyl was found to be the most effective in suppressing the radial growth of the strain, with an EC₅₀ of 1.91 μg·mL^-1, followed by pyraclostrobin, with an EC₅₀ of 2.25 μg·mL^-1.

Key words: tea plants, twig wilting, Botryosphaeria spp., indoor toxicity test