18 BULLETIN 153, U. $. DEPARTMENT OF AGRICULTURE. © 
branches, but the leader from year to year seems to develop as 
commonly from one of the lateral buds as from the terminal one, 
resulting in a crooked bole. The ash plantations examined have 
erown too slowly to make pruning a profitable operation, but if 
especially straight stuff is desired it can be obtained either by very 
close spacing or by pruning. Ash will grow fairly straight if spaced 
closely, and pruning should accomplish the same result as close 
spacing. One method of pruning is to cut off each year the lateral 
shoots which threaten to compete with the leader; another is to 
pinch off the lateral buds formed near the tip on the terminal shoot. 
The branches of European larch die early, but are very persistent. 
Pruning this tree does not pay, however, because the products of 
the plantation (chiefly posts and poles) are almost, if not folly; 
as valuable when somewhat knotty as when clear. 
Cottonwood prunes itself exceptionally well, and soft maple, pine 
cherry, and Scotch pine also lose their branches readily. The oaks, 
as a rule, are not good self-pruners, but they grow so slowly that 
pruning is not a profitable operation. 
MIXTURES. 
Comparatively few plantations of mixed species have been set 
out in the region under discussion, and in the few cases where this 
has been done the mixture has usually proved unsuccessful. This 
has been due, however, more to the planters’ ignorance of the require- 
ments of the species planted than to any essentail defect in the 
method itself. A mixture of two or more species is often desirable. 
Some trees, such as cottonwood and European larch, need tobe 
spaced widely, while others, like black walnut and black locust, 
have such a scant foliage that they do not shade the ground com- 
pletely enough to prevent the growth of a heavy sod of grass. In 
such cases a mixture will more completely utilize the area planted, 
thus increasing the yield, and at the same time will bring about 
better forest conditions in the plantation. 
Mixtures are desirable for other reasons. Planting stock of such 
species as white pine and European larch is expensive, and a less 
valuable species mixed with the main crop, and removed later m 
thinnings, will keep down the first cosi. If a species to be planted 
is susceptible to serious insect or fungous attack, as is white pme — 
or black locust, the mixture of another species not susceptible will 
provide for a stand of trees on the area in case the pine or locust 
is killed. When suchspecies as European larch, white pine, or black 
walnut are widely spaced, in order to promote the most rapid 
growth, it may be advisable to interspace the area wale some more 
tolerant and slower-growing species. 
A number of mixtures are given below which should prove suc- 
cessful on soils adapted to both species of the mixture, and which 
