Foot rot disease of sweet potato in Japan caused by Diaporthe destruens : first report, pathogenicity and taxonomy

Foot rot, also known as stem rot or tuber-root rot syndrome, on sweet potato occurs in sweet potato fields in Okinawa, Japan. Isolates of one fungal species that was consistently isolated from affected sweet potato produced pycnidia having alpha and gamma conidia. The same symptoms as those in the field were produced in vitro after inoculation of test plants with a representative isolate. Based on morphological and molecular phylogenetic evidence, we identified the fungus as Diaporthe destruens . This is the first report of the occurrence of foot rot on sweet potato caused by D. destruens in Japan.