NATURAL REGENERATION OF DOUGLAS FIR. NS 
Douglas-fir region by collective effort through an assessment plan. 
The annual cost averages about 24 cents per acre. The need for ade- 
quate protection from fire is urgent in the various stages of the Doug-, 
las-fir forest from its beginning to its maturity. 
DISEASES. 
Fortunately no diseases have been found that threaten the Douglas- 
fir forest. The only serious attacks occur in the young seedlings and 
in*the overmature trees. mh 
From the time the seed swelis before germination until the seed- 
ling has formed woody tissue at the age of 30 to 40 days, losses 
are caused by the damping-off fungi, and these losses sometimes 
become serious. After the seedling is established the Douglas fir 
is essentially free from disease until it has reached the age of about 
150 years. In the overmature forest it is seriously attacked. As 
the forest under management will be cut between 80 and 120 years 
of age, it promises to be practically free from disease. 
The rots in the present overmature forests, however, have a direct 
bearing on the future crop. Trees that have been attacked seriously 
enough to render them unmerchantable may be left standing to 
serve as seed trees. It has been shown that such trees produce less 
seed, but that the quality is apparently as good as that of the seed 
from sound trees. The rots that cause the most damage are the 
ring-scale fungus (Trametes pint), the velvet-top fungus (Polyp- 
orus schweinitziz), the quinine fungus (/omes laricis), and the rose- 
colored fomes (Yomes roseus) .1® 
INSECTS. 
In comparison with some other important forest trees in Oregon 
and Washington, Douglas fir ordinarily suffers but little from tree- 
killing insects. Probably the most important Douglas-fir insect in 
the region is the Douglas-fir beetle (Dendroctonus pseudotsuga 
Hopk.), which kills Douglas fir by mining out the inner bark. 
Losses caused by this insect are far more frequent in the border 
type than in the Douglas-fir region proper. 
The felling and barking of the infested trees beginning with the 
first of November and ending with the first of the following March 
will be sufficient to kill the broods. The barking of newly infested 
trees during July and the first half of August is also permissible 
in the case of this species and sometimes desirable because this is 
the period in which the principal larval development takes place 
and before the broods of adults have matured sufficiently to fly 
when liberated from: the bark. 
The fact that the species is attracted to the living bark on trunks 
and stumps of recently felled trees suggests the efficiency of the 
trapping method of control. 
Continued cutting operations within a given locality, especially 
in the coast region, usually serve to protect the living timber from 
attack by this beetle. 
In case areas are found infested by this or other bark beetles, 
the Bureau of Entomology should be consulted for advice as to the 
method of control most suitable in the given locality. 
16 Boyce, J. S. Decay in Douglas Fir. The Timberman, Vol. XXIII, No. 1, Nov., 1921. 
