D 
WESTERN WHITE PINE AND LARCH-FIR FORESTS 27 
for a second cut later, in, perhaps 25 to 40 years. There is very 
little profit in handling white pine under 12 or 14 inches in diameter, 
and trees of this class should be left for further growth. Frequently 
in stands of this sort there are a good many small cedar poles which 
will yield good returns if left to develop into 35-foot poles. 
THINNING IMMATURE STANDS 
Opportunities for thinning young stands are limited by the slight 
demand for small-sized material. However, on accessible areas along 
railroads or roads, particularly in farmers’ wood lots, where there is 
a market for. pulp wood, it may be possible to take out white fir 
and hemlock which occur in mixture with white pine and so stimulate 
the growth of the remaining pine. 
PLANTING 
Many areas have been burned and reburned until there is no pros- 
pect of their reproducing naturally for many years. The only 
method of restoring such areas to productivity is by planting with 
nursery stock. 
The Forest Service has for many years been planting such devas- 
tated areas in Idaho and western Montana with western white pine 
at the rate of 2,000 to 3,000 acres a year. ‘Two or three year old 
nursery plants are generally used. The cost, including cost of the 
stock, averages about $10 an acre. The plants are usually spaced 
about 8 by 8 feet—about 680 plants to the acre. Planting may be 
done either in the spring or late fall. 
CONTROL OF DISEASES AND INSECTS 
WHITE PINE BLISTER RUST 
The white pine blister rust now exists on white pine in Canada less 
than 100 miles north of the Idaho line. Just what effect it will have 
on the possibilities of growing western white pine in the United 
States it is difficult to predict. It seems inevitable that the disease 
will sooner or later appear in Idaho, though its progress may be 
greatly delayed by the practical elimination of the culivated black 
currant, through which it spreads most rapidly. 
It has been demonstrated in New England that white pine can be 
successfully grown in a region infested with blister rust through 
eradication of currants and gooseberries, the alternate hosts of the 
disease. Preliminary experiments in north Idaho have indicated 
that wild currants and gooseberries can be cleared from white pine 
land for about $1 to $1.50 an acre. This will doubtless have to be 
considered as one of the costs of growing white pine. 
INSECTS 
The principal insect enemy of white pine is the mountain pine 
beetle, Dendroctonus monticolae. 'This bark beetle has caused very 
extensive losses of white pine in the past. Incipient attacks can be 
controlled by felling trees and peeling the bark. While this beetle 
may do considerable damage in virgin timber, it is believed that 
