Morphology and pathogenicity of Alternaria panax isolated from Panax schinseng in Japan and Korea

Morphological variation of the conidia of Alternaria panax isolated from Panax schinseng and its pathogenicity were studied. The conidia of the isolates formed in natural habitats usually had long beaks and were more uniform in size than those produced in vitro. In aging or axenic growth, excessive cellular swelling was recognized characteristically in the fungus. Surface structure of the conidia and chain formation also varied with the culture media and the age of the colony. Based on the review of the literature and the result of the experiments, it is concluded that the description of the fungus described by Nakata and Takimoto in Korea and Japan does not coincide with A. panax. The isolates of A. panax incited foliar diseases not only in P. schinseng but also in other members of the Araliaceae tested. On the leaves of P. schinseng, Aralia elata and Schefflera arboricola, severe leaf spots and blights developed after artificial inoculation, but on the leaves of Fatsia japonica, symptoms were produced only around the wounded part and slowly enlarged. A. elata and F. japonica were found to be new hosts of the fungus.