We have a lot of trees on the farm (Apple, maple, pear, walnut, oak...) and I've been reading about pruning lately. One of the things I stumbled upon is that when a tree is say five feet tall and has a branch at 18 inches above the ground there will always be a branch at 18 inches (even if the tree grows to 50 feet). Is this true? I assume this would also apply to Y's in trees where the trunk separates into two different sections. If you want a good looking tree ideally you don't want a big branch 18 inches off the ground, so you'd prune it.
So, basically, is it true that when a branch grows in it will always remain at the height it started out at?