First report of Didymella bellidis causing tea leaf spot in China.
In recent years, the tea plant (Camellia sinensis) has been widely planted in Guizhou Province, China, with a cultivated area of 350,000 ha in 2017. In November 2018, leaf spots were observed on tea plants in Yuqing County. Disease incidence was estimated at 74 to 82%, and disease severity was estimated at 42 to 48% in 12 tea plantations. Early symptoms on infected leaves were light brown lesions, which gradually enlarged to brown, scattered, round, elliptical or irregular lesions. The central area of each lesion later became grayish and surrounded by an inconspicuous yellow halo. Neighboring lesions coalesced to form larger lesions at the margin of the leaves. To identify the pathogen(s) causing this disease, leaf samples were collected. Based on morphological characteristics, molecular data (sequence analysis of the internal transcribed spacer, partial 28S large subunit rDNA, and beta-tubulin genes) and pathogenicity tests, the causal agent was identified as Didymella bellidis. This is thought to be the first report of this fungus causing a tea leaf spot in China and seriously reducing both the productivity and the quality of tea leaves.