Young trees usually grow faster when pruned as little as possible in their first three to five years. The leaves produce the food not only for the branch they are on but also for the trunk and roots. By cutting off a branch you remove leaves that could contribute to overall growth.
Specialists once believed that if a branch must eventually come off, the sooner it was done, the safer it was. That is true for healing of wounds, but not for growth of the trunk and roots.A young tree left completely unpruned will grow faster than if pruned at any time.
To thicken the truck, you must permit leaves and branches to grow on it. If all the lower branches are removed from the main truck to a height of six to 10 feet, development of the trunk will be retarded. Cutting off the lower branches each year while the tree is dormant will hasten trunk growth, but the trunk will be more slender and the root system smaller.
If temporary branches (those that eventually should come off) are left on the trees for three to five years, the tree will be as tall as the one from which they are removed; however, the trunk diameter will be larger and the root system better.
When the trunk and roots are strong enough to support a large top, the temporary branches should be removed. Usually, it is a good idea to remove a few each year, taking the biggest ones first, to avoid larger wounds. If none is thicker than a 5-cent piece, remove the lowest branches first.
Structural weaknesses should be eliminated but not necessarily immediately. The Y-crotch is among the worst. It results from too narrow an angle between the trunk and a limb, causing the limb to go upward instead of outward. As growth proceeds, both increase in diameter and finally they press against each other, making both vulnerable to heavy winds. An easy way to eliminate the Y-crotch is to remove the limb while it is still small.
Another structural weakness is limbs too close together. If two branches, each about the diameter of a pencil, are spaced about a foot aprat, the spacing may seem adequate. But when each increases to six inches in diameter, they wlll touch each other. This should be considered when selecting the permanent branches of the young tree.
A serious structural weakness exists when several limbs come from different sides of the trunk at about the same level. They are weak and tend to keep the top from getting moisture and nutrients.
Crooked growth can be corrected while a tree is still small, and preferably in early spring. Use hand pressure to straighten the trunk. This will rupture the cells inside the curve. Stake the tree after bending. Healing will be rapid. If a trunk has two curves, straightening is best done in two stages.Correct the lower one first, and do the other the following spring.
Do not allow unskilled workers to prune your young tree. Of course, the tree will not die from faulty pruning. But it may be crippled and changed from an attractive specimen to a stylized, undesirable form.