A young tree sometimes has structural weakness which should be corrected early in its life. They are easy to recognize and farily easy to take care of. Pruning is the way to do it and one of the best times is late winter or early spring before new growth starts.
The worst one is the Y-crotch, which results from too narrow an angle between the trunk and a limb, or between two limbs. As growth proceeds and they increase in diameter, they press against each other.
Instead of the union between the two becoming stronger as it would if they were at right angles to each other, weakness develops and in a windstorm the Y-crotch may split wide open.
In other words, if the branch is growing almost at a right angle from the trunk, there is no weakness; but if the branch is growing more upright, at about 45 degrees, as time goes on they are going to press against each other.
An easy way to eliminate the Y-crotch is to remove the branch while it is quite small. Do not let it become an important part of the permanent structure of the tree.
Silver mpales and American elms are very prone to have Y-crotches, so much so that they are hard to prevent. It is the main reason these trees are so likely to split apart in a heavy wind or ice storm.
Other weaknesses that should be corrected are branches too close together, and two more branches growing in different directions at the same height.
On a young tree, it two branches about the diameter of a pencil are spaced about a foot apart up and down the trunk it may seem adequate. But both will increase in diameter as the tree gets larger and sooner or later may be almost touching each other.
For example, if a branch is 8 feet from the ground, then 30 or 40 years later, the center of the branch still will be 8 feet from the ground. But because it will have increased in diameter, the distance between the branch and the ground or between the branch and the one above it will be less. In other words, the height of the branch does not increase as the tree gets taller.
When selecting the permanent branches of a small tree, therefore, it is important to see that they are not too close together.
Two or three limbs growing from different sides of the trunk at nearly the same height is a serious weakness.The food manufactured in the leaves moves downward in the inner bark while the water and nutrients absorbed by the roots move upward through the sapwood. When there are two or more branches at the same level, food and nutrients tend to move into these branches to the detriment of other parts of the tree.
If a young tree is crooked, it can be corrected while the tree is still small if it is objectionable (some gardeners consider such a tree to have more individuality).
The time to do this work is in ealry spring. Use the pressure of your hands to straighten the trunk. This will rupture the cells on the inside of the curve. Stake the trunk after bending it. it will heal rapidly.
To speed the growth of a young tree, it should be pruned as little as possible in early life.
A young tree left completely unpruned will grow faster and have a more sturdy trunk than one that is pruned at any tme by any method.
However, if the tree has a Y-crotch, it should be elminiated early because the smaller the wound, the sooner it will heal.
If branches are too close together, it may be a good idea to wait three or four years before removing some of them. Too oftern all the lower branches are removed from the trunk to a height of 8 to 10 feet. This seriously retards the development of the main trunk.
When you remove healthy leaves from a young tree, including those growing along the lower trunk, you remove food producers.
The leaves do not produce food only for the branch on which they are growing. They also contribute food for growth of trunk and roots. The longer branches (that eventually will be removed) are left on the tree, the faster the tree will grow.
Stretch the pruning out over a period of years if practical. The limbs of a tree normally are protected from thehot sun by a leafy canopy. When this canopy is broken by heaving pruning, the hot sun may burn the tender bark which is unaccustomed to such heat.
This can result in sunscald which can kill a tree in a single season.