When installing supports or attaching things to your trees remember to make the attachment out of something that will not hinder the tree in future years.  It is a good idea to put on something that will move as the tree grows and not cut into the bark of the tree.  Putting a short peice of hose over a wire will often solve this problem.

Notice in the above pictures how the wire around one of the main branches of this elm has greatly reduced its ability to transfer nutrients to the upper parts of the tree.