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ON A NEW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc 
18. General Summary. 
1. The present canker disease was first noticed in Sapporo in 19 13 and its 
distribution is at present limited to Hokkaido. 
2. The canker disease is not only common on Pmnus yedoensis, P. sachali- 
nensis and P. Mumc, but it is also found on a number of other species 
of Prunus. The identity of the fungi which were found parasitic on 
P. ycdoensis, P. sachalinciisis, P. Miune and P. Persica was proved by 
cultural and inoculation experiments. 
3. There are two different types of symptoms in the diseased branch. The 
one is the cankered type and the other is the girdled one, which never 
forms a canker. 
4. The causal fungus belongs to the subgenus Euvalsa and is new to science. 
It is described under the name of Valsa japonica Miyabe et He.mmi. 
5. In the saprophytic condition, Valsa japomca seems to be almost omnivor- 
ous. On a comparatively high acid medium such as fruit-juice, the 
fruiting pustules are not generally produced, in spite of the vigorous 
growth of its mycelium. The fruiting pustules are, however, most 
readily produced on the host-bark-decoction-agar, oat-juice-agar, and 
also on the sterilized twigs. 
6. The mycelium of the present fungus on artificial cultures turns yellow, 
greenish-yellow or light brown color with age. 
7. The fungus produces a blackening of the media and grows more luxuri- 
antly on cultures containing a low percentage of tannic acid than without 
it. But the high percentages of tannic acid inhibit its growth entirely. 
The fruiting of the fungus is also stimulated by low percentages of 
tannin. 
8. Corrosive sublimate has the strongest sterilizing power for the hyphae 
of the fungus, and a 0.05% or 0.1 % solution is the most effective. But 
copper sulphate and carbonate of soda are not effective for the same 
purpose. 
