Morphological and Molecular Characterization of Botryosphaeria wangensis Causing Branch Blight of Acer saccharum in China

Acer saccharum Marsh., valued for its ornamental, material, and edible uses, is an important temperate tree species in the Northern Hemisphere. A blight disease affecting branches of A. saccharum was first identified in 2023 in Shandong, China. The causal agent was identified as Botryosphaeria wangensis G.Q. Li & S.F. Chen based on cultural and morphometric characteristics. Phylogenetic analysis was performed by amplifying and sequencing the internal transcribed spacer (ITS) region of rDNA, the translation elongation factor 1α (tef1) partial gene, the β-tubulin (tub2) partial gene, and the second largest subunit of RNA polymerase II (rpb2), in combination with morphological data. Symptoms observed in the field were replicated in a pathogenicity test through inoculation of A. saccharum branches, thus satisfying Koch’s postulates. To our knowledge, this is the first report worldwide of B. wangensis infecting A. saccharum.