First report of Alternaria alternata causing leaf spot on Bruguiera gymnorrhiza in China.
In a survey conducted in March 2014, a leaf spot disease on Bruguiera gymnorhiza was observed in Sea View Promenade in Zhanjiang, Guangdong, China. Symptoms on leaves initially appeared as small circular to irregular, dark brown, necrotic, sunken spots with an average diameter of 4-7 mm. The spots gradually enlarged in size, becoming irregular or remained circular with concentric rings or zones. In the latter, the spots coalesced, and the leaves withered, dried and fell from the plants. The causal pathogen was identified as Alternaria alternata based on cultural, morphological, genetic (ITS) and pathogenicity analyses. This is thought to be the first report of A. alternata on leaves of B. gymnorhiza in China.