A well-formed tree is characterized by branches that are spaced uniformly both along and around a sturdy trunk, at right. This habit insures that relatively long, uninterrupted columns of wood fibers will run the length of the trunk, imparting maximum strength to the tree.
This property is perfectly illustrated by the strong, uninterrupted wood fibers of a baseball bat.
However, when a tree trunk grows around numerous, close-spaced branches, at left, the columns of wood fibers are interrupted and large seams of bark may be imbedded within the trunk. This often results in a weak spot where a tree may snap during severe weather, below right.
To prevent this scenario, it's very important to perform corrective pruning on young trees to establish a well-spaced branch arrangement. This pruning task will generally take less than ten minutes and can usually be completed from the ground with nothing more than sharp hand and pole pruners.
In fact, if you'd like to learn how to prune young trees correctly and, in turn, help your community's urban forest grow strong, consider joining the Cornell Cooperative Extension - Onondaga County's "Communitree Steward" program.