TAKEWO J 1EMMI 
SOS 
c. Buds. 
As already shown by the inoculation experiment, the germ-tubes and 
hyphae of this causal fungus have the power to kill the buds of the host plant, 
although I failed to secure infection of the bark of the twig. 
In the case of Valsa leucostoma Peks., the causal fungus of the "die- 
back" of the peach tree, Rolfs (1907) " !) also suggested it to be a channel of 
entrance of the disease. 
d. Insects. 
Insects are found in great numbers both in and on the bark of the host 
plants in the vicinity of Sapporo, and it is reasonable to believe that they 
may crawl over sticky spore horns and carry the spores away to deposit them 
on wounds, and thus start new cankers. Indirectly, insects may be connected 
with the spread of the disease by making wounds in the bark, where the 
spores may gain entrance after having been carried by some other agents. 
I am now of the opinion that this is the way in which insects are most closely 
related to the dissemination of the disease. In the fall of 1914, I found many 
larvae of Sesia hector BurL., commonly known by the name of " Kosukashiba" 
in Japan, feeding on the diseased portions in almost all infected parts of the 
smooth bark on trunks. According to Profs. Matsumura and Niijima, 
Sesia hector BuTL. is the most common noxious insect, whose larvae inhabit 
the baric and wood of the trees, which belong to the genus Prunus, in Japan. 
It is also written that this insect is found mostly on the trunks of aged trees 
and causes the gummosis of the host plant. The fact that the present disease 
is very common on the trunks of old trees shows beyond all doubt that infec- 
tion on such a smooth bark originated for the most part in the exit holes of 
this insect. 
There are, besides, two or three kinds of bark borers in the vicinity of 
Sapporo, found on the living and dead trees of the hosts. 
