TAKEWO HEMMI 263 
greater its resistibility to this disease. 
Even on a single tree the disease is most frequently found on the thick 
branches or trunks, and the cases on the twiglets are very rare, if ever attacked. 
When the disease affects the young twig, the pustules of the stromata are very 
small, covered by the periderm for a long time without being ruptured ; and 
the spores are in such a case very rarely produced, for the twigs die and dry 
up very rapidly. In the case of Prunus Mume, the canker is generally pro- 
duced on comparatively small branches, having the diameter of one and a half 
centimeters or more. 
4. Host Plants. 
The disease in question was first found on Prunus yedoensis, which is most 
severely attacked. By extending our observations to other species of Prunus 
we found a similar disease on most of them. The trees affected by the disease 
are Prunns sachalinensis Koidz. n> •¥ -f ? 7), P. Koidzumii Matsum. ( a 
1/ ■¥ 9 7), P. serrulata Lindl, (-v -r "9* ? 7), P. serrulata Lindl, var. nobiiis 
(Koidz.) /. Yökihi (AflCtH #J Ä iE). F - kurilensis Miyabe >s-*r*r? 7), 
P. Mume S. et Z. f), and P. Persica S. et Z. (=e \ ). 
The identity of the fungus which attacks P. sachalinensis, P. Mume, and 
P. Persica causing the canker-disease was proved by cultural and inoculation 
experiments. 
( )n Prunus serrulata, the pyenidial stage only of the fungus has been ob- 
served. On Prunus serrulata Lindl, var. nobiiis, the canker is most beauti- 
fully formed, showing apparently the weak power of its resistance to the 
disease. The specimen on Prunus kurilensis having both ascosporous and 
pyenidial stages was collected by Prof. S. Itö in May of 191 5 on the dead 
twig. The specimen on Prunus Roidzumii was collected by myself on the 
dead twig, but the fungus is lacking in the ascosporous stage, and its parasi- 
tism is not clear. In regard to the causal fungus of the disease on these host 
plants, I have not been able to undertake the cultural and inoculation experi- 
ments. 
