The spacing of branches, both vertically and radially in the tree is very important. Branches selected as permanent, scaffold branches must be well-spaced along the trunk. Maintain radial balance with branches growing outward in each direction. Thus a tree that will be 50 feet tall should have permanent scaffold branches spaced about 18 inches apart along the trunk. Avoid allowing two scaffold branches to arise one above the other on the same side of the tree.
Some trees have a tendency to develop branches with narrow angles of attachment and tight crotches.
As the tree grows, bark can become enclosed deep within the crotch between the branch and the trunk. This is called included bark. Included bark weakens the attachment of the branch to the trunk and can lead to branch failure when the tree matures. You should prune branches with weak attachments while they are young. Avoid over-thinning the interior of the tree.