Black Leg Disease in Wasabi Caused by Phoma wasabiae

Phoma wasabiae에 의한 고추냉이 먹들이병(묵입병)

A black leg disease in wasabi occurred, showed black spots on the leaves, changed a rhizome color to black by invading the vascular bundles of stem and root, thus lowered the quality of the rhizome. The mycelium of the pathogen was yellow at first and then turned to dark yellow on oat meal agar medium. The pycnidium was globose or subglobose, dark brown in color, and 44~120$\times$28~170 ${\mu}{\textrm}{m}$ in size and had one or two ostioles on the upper part. The pycnidiospores are single-celled, hyaline, and 4~6$\times$1.2~2.3 ${\mu}{\textrm}{m}$ in size. The causal pathogen was identified as Phoma wasabiae. The black leg disease of wasabi occurred within the range of 28 to 32% at Chonbuk province in 1994~1995. The disease was appeared from April to October and severe in June and July. The black leg caused by P. wasabiae was first described in Korea.