Proper pruning is essential in developing a tree with a strong structure and desirable form. Trees that receive the appropriate pruning measures while they are young will require little corrective pruning when they mature.
Here are a few simple principles to know about tree pruning:
Each cut has the potential to change the growth of the tree.
Proper technique is essential. Poor pruning can cause damage that lasts for the life of the tree.
Trees do not heal the way people do.
When a tree is wounded, it must grow over and compartmentalize the wound. As a result, the wound is contained within the tree forever.
Small cuts do less damage to the tree than large cuts.
For that reason, proper pruning (training) of young trees is critical. Waiting to prune a tree until it is mature can create the need for large cuts that the tree cannot easily close.
Making The Cut
The location of the pruning cut is critical to a tree’s response in growth and wound closure.
Pruning cuts should be made just outside the branch collar. Because the branch collar contains trunk or parent branch tissues, the tree will be damaged unnecessarily if it is removed or damaged. In fact, if the cut is large, the tree may suffer permanent internal decay from an improper pruning cut.
If a permanent branch is to be shortened, it should be cut back to a lateral branch or bud. Cuts made between buds or branches may lead to stem decay, sprout production, and misdirected growth.
Source: www.treesaregood.com