I used the tree tubes that Esshup recommended and could easily tell a difference between those in and out of a tube.
I wish the stakes were a little longer and the tubes had a few more factory holes as they weren't at top of tube once driven down far enough to keep it upright and some tubes buckled over in wind as a result. I will probably order some more tubes from them next year as I plant more.
I have used 3/4" Sch 40 PVC pipe for my tree tube supports. They keep the tubes from buckling, but allow the tube to "wiggle" just enough in the wind that the trunks of the saplings thicken up properly at the base. I attach them with heavy duty removable zip ties, since I need to weed and prune the trees in my area a few times before they are mature enough to be liberated from the tubes.
They have supported my trees safely until they are 2-3 feet out of the top of my 5' tubes. However, at that point the trees have enough potential wind area that storm winds will break my zip ties and flatten the trees.
I then move on to Phase 2 of protecting the trees, which also involves some elevated fencing because my deer will stand on their hind legs and eat the tree tops out of the 5' tubes.
