Blister Canker, a New Disease of Peach Tree

Abstract

Blister canker, a new disease of peach tree was found in 1965 in Kanagawa Prefecture and also, in Gunma, Shizuoka, and Okayama Prefectures. The disease is caused by a fungus belonging to the genus Physalospora which produces both perithecia and pycnidia in infected bark tissues. The newly invaded bark tissue swells up and finally shows rough appearance, resembling blisters. In later stages, gum oozes out from these blisters, and infected twigs finally die.
The fungus shows the following morphological characteristics: perithecia mostly scattered, partly imbedded, black, globose to subglobose, ostiolate, about 150-290μ in height and 170-340μ in diameter; asci 8-spored, clavate, wall thick especially at the apex, hyaline, 57.5-87.5×12.5-22.5μ; paraphyses erect, filamentous; ascospores nonseptate, hyaline to slightly tinted, ellipsoid, 15.0-32.5×5.0-12.5μ; pycnidia (Macrophoma) scattered, partly imbedded, black, globose to conical, about 240-440μ in height and 240-590μ in diameter; pycnospores hyaline, non-septate, fusiform elliptical, 20.0-35.0×5.0-12.5μ and produced on conidiophores about 20μ long. The inoculation test indicated that the fungus is pathogenic only to peach.
Since no fungus corresponding to the Physalospora here described can be found in the literature, this fungus is treated as a new species, Physalospora persicae Abiko et Kitajima.