First report of leaf spot (Corynespora cassiicola) in Assam indigo in Japan

摘要

Leaf spot caused by Corynespora cassiicola was observed on plants of Assam indigo (Strobilanthes flaccidifolius) in Higashi village in Okinawa Prefecture, Japan, in October 2019. The fungus isolated from diseased leaves was identified based on morphological characteristics and molecular analysis of the rDNA-ITS region. Inoculation tests using the isolated fungus confirmed Corynespora cassiicola as the causative agent of the disease. To the best of our knowledge, this is the first report of leaf spot disease in Assam indigo caused by C. cassiicola in Japan. Leaf spot, "hanten-byo" in Japanese, is the proposed name of the disease.