4 The Colorado Experiment Station. 
and may cause late growth and unfruitfulness. To give the desired 
results one must summer-prune shortly before the season of growth 
ends; earlier pruning starts new growth, while late pruning gives no 
results. The benefit derived from summer pruning seems to depend 
upon the ability of the pruner to prune at a time to bring about early 
maturity. In an irrigated section where soil conditions are easily 
controlled, the same end may, no doubt, be more easily attained by 
proper manipulation of the irrigation water. 
Both the season at which the wound is made and the character 
of the cut have an influence upon the healing process. The pruner 
should remember that all food material capable of healing a wound 
is taking a downward course through the inner bark and that, to 
heal well, a wound must be in a position to intercept the downward 
flow of sap from foliage higher up. When a limb is to be removed 
entirely, the cut should be at the union with, and parallel to the sur¬ 
face from which the limb arises. Where limbs are to be headed- 
back they should be cut to a side limb and not to,a bare stub. 
Wounds naturally heal best when made at a season of the year when 
growth is most active, but, with the possible exception of wounds 
made in early winter and subjected to a long season of drying, the 
season at which the wound is made has no important bearing upon 
the healing process. The grower who has a small orchard that 
will permit of such a practice, should delay the pruning until as 
near the opening of the growing season as possible. 
The influence of pruning upon the fruit-bearing habit of the 
tree has been briefly mentioned, but the following pages will show 
how a fruit-bearing habit may, to a certain extent, dictate a course 
in pruning. The fruits with which this discussion has to deal have 
two general types of fruit-bearing; from terminal fruit buds and 
from axillary fruit buds. The first type of fruit bud is well repre¬ 
sented in the apple and pear, and the latter in the stone fruits. Trees 
which produce axillary fruit buds are naturally more prolific and re¬ 
quire severe pruning as a means of thinning the fruit. In fact, a 
system of pruning under which the tree with axillary fruit buds 
would thrive, would cause the apple tree to overgrow to such an 
extent that it would be rendered almost barren. The point may be 
more fully illustrated by comparing the peach and the cherry. Al¬ 
though both develop axillary fruit buds they differ in their fruiting 
habits; the fruit buds of the cherry are seldom found on the stronger 
growing new wood, and severe pruning, as practiced on the peach, 
would throw much of the strength of the tree into the production 
of strong wood that would carry very few fruit buds. We have 
said that in the apple the type of fruit-bearing is from terminal buds, 
yet, many varieties develop axillary fruit buds. Varieties which 
develop axillary fruit buds and bear terminal fruit buds on young 
