1. When the growth of Picea jezoensis in the natural forest of the Imperial Household Forestry at Tomakomayi in Hokkaido is considered, it seems that the growth is suppressed up to approximate age 91-156, i.c., at the diameter breast-high about 21cm., After the above unfavorable period, the growth is much fasten till the diameter breast-high becomes about 42cm.
At the diameter breast-high of about 42-60cm., the growth of Picea jezoensis is again under somewhat unfavorable condition, whereas at more than about 60cm., it regains vigorous growth.
2. So far as the natural forest of Picea jezoensis at Tomakomayi is concerned, Trametes Piceae “the Ring-scale Disease” of Picea jezoensis generally attacks the trees during their suppressed growth period, i.c., at the age of about 91-156, the diameter breast-high about 21cm.
3. The causal fungus has been misconceived to attack an old trees of Picea jezoensis or Picea Glehni simply from its outside look of trees infested by the fungus. However, it must be amended that the fungus attacks the trees through branches that have died naturally, at the changing period of the growth from the young to the mature.
4. The young trees under a suppressed condition should be thinned and the overwood be removed by fellings. When the opperation is properly performed, the danger of infection can be removed and the growth may be promoted by the moderate sunshine and ventilation.
5. The trees in a commercial sylviculture should be thinned to promote their growth. The lower branches consisting of a heart-wood must be sawed off prior their natural death.
6. Dying branches must be sawed off near the trunk and never left on it.
Bureau of the Imperial Household Forestry, Sapporo Branch. April, 1932.

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