First report of stem blight on Joseph’s coat amaranth ( Amaranthus tricolor L.) caused by Diaporthe amaranthophila (Inácio, Dianese & Carlos) Rossman & Udayanga in Japan

In September 2015, stem blight was found on Joseph’s coat amaranth ( Amaranthus tricolor ) in Kanagawa, Japan. A fungus was isolated from brown spots on the stems and leaves. After our inoculation tests using the isolated fungus, the same symptoms were observed in the field. The pathogen was identified as Diaporthe amaranthophila based on morphological and molecular analyses. This is the first report of D . amaranthophila as a pathogen of stem blight on Joseph’s coat amaranth in Japan.