First report of Neofusicoccum parvum associated with blotch trunk disease of Koelreuteria paniculata in China.
Koelreuteria paniculata, as one of the most economically important trees in China, is known for its expensive heartwood, which can be used to produce furniture and pharmaceuticals. It also has high ornamental value, and it is often used for its stress-relieving properties. Since 2017, K. paniculata located in Chengdu, Leshan, and Guang'an in Sichuan Province has developed blotch trunk disease. In favorable temperatures (28 to 35°C), the incidence of this blotch trunk disease was evaluated as 70[%] in a plantation. Gray-white dots initially appear on the branch cortex and then develop into round gray plaques. Later, the leaves of the infected branches defoliate and die, followed by the drying and death of the whole plant. Pathogen fruiting bodies, scattered on the gray plaques, are an additional sign of the disease. The causal pathogen was isolated and identified as Neofusicoccum parvum based on morphological characteristics, molecular data (sequence analysis of the ITS region, ß-tubulin gene and translation elongation factor 1-alpha (EF-1a)) and pathogenicity test. This is thought to be the first report of N. parvum as a causal agent of blotch trunk disease on K. paniculata in China.