First impressions: you take nice pics, you have some nice looking trees and you are probably the kind of person who is going to have success with your trees because it is clear you care.

As to your question: There are three reasons to prune the young trees. One is to clip the tree back at planting time in order to get some side branching. Another reason is to make sure that the root structure can support the growth at the top (and that is probably why you have pruned at planting time in the past). The third reason is to develop the structure of the tree.

http://www.wvagriculture.org/images/Lit ... _Trees.pdf

As to reason #1: You seem to have adequate side branching already on those trees and this does not justify clipping the trees.

As to reason #2: This is really the basic question. The question is will the roots support the top of the tree. Part of the answer may have to do with what you observed yourself at planting time. Did the trees have a good root structure? Did you have to clip back any of the roots when you planted them? If there is a problem with the roots then probably it would be helpful to clip back the top of the tree and the sooner you do that the better. Forget about the nice leaves you see but just clip out a little. You will NOT ever kill the tree by clipping it back or pruning it.... but only delay its progress. On the other side of the equation, you are also not likely (in my opinion) to kill the tree by not clipping it back either but I am less sure of my answer on this and it may depend on just how well and how quickly the root structure is established.....but I seriously and strongly suspect that your trees would do fine if you just left them as is. Bottom line is (and this is only an un-professional guess) I think you could go either way on this one but the safest method might be to do a little clipping.

As to reason #3: you already have your limbs pretty well developed for the later scaffold limbs you will develop. Sooner or later you are going to have to take some of the limbs off, but there is an argument to be made to trying to make the tree as vigorous as possible and do most of your cutting later after the tree has had a chance to grow and develop.

In other words, basically you don't need to do any pruning and it is only reason #2 which is of consideration.

What might I do? I might take out the side branches with narrow upright crotch angles now. Later in the trees history you might try spreading these kinds of limbs , but at this point I would simply cut them out. Select out a few of the side branches where you already have loads of side branches. And tip the top of each tree a bit, not because you need side branching, but only because you want to discourage apical dominance and you want to give the tree a chance to stiffen up a bit as it gets established......let the tree get established this year and then do very little pruning for a couple years.....later develop its structure.

but what do I know? Others may see it better and differently.