Abstract
In the autum of 1919 as well as of 1920, a canker disease injurious to the Japanese osier, Salix purpurea var. angustifolia appeared in the vicinity of Sapporo. The disease seems to be prevalent at several osier-holts in Hokkaido.
The disease is due to a Pyrenomycetous fungus, Physalospora Myabeana n. sp. and its conidial form Gloeosporium.
The relationship between the perithecial and conidial stages was established by cultural experiments.
The writer wishes here to express his heartiest thanks to Prof. K. Miyabe and Prof. S. Ito for their kind suggestions and criticisms and also to Dr. T. Hemmi, who has kindly helped him in the cultural study of the fungus.
