Leaf spot of Hydrangea macrophylla caused by Corynespora cassiicola in China.
Hydrangea macrophylla, also known as big leaf hydrangea, is an economically valuable ornamental garden plant. From 2016 to 2018, a high incidence of leaf spot disease of hydrangea occurred in Hunan Province of China. Symptoms consisted of irregular to circular lesions, dark brown in color with gray-white centers and delimited by dark brown borders. The lesions further coalesced to form irregularly shaped necrotic areas and extended to the leaf apex resulting in leaf wilt. A fungus was consistently isolated from the symptomatic plants and identified as Corynespora cassiicola by morphological characters and phylogenetic analyses. Pathogenicity was confirmed by fulfilling Koch’s postulates. This is the first report of C. cassiicola causing leaf spot on H. macrophylla in China.