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Question from Larry, Longmont, CO (received 5/26/20) -

I planted a cluster of Aspen trees last November. They are growing nicely, however the tallest one seems to have no center stem at the top. Rather than having one main stem growing up, it looks like that was broken or cut once upon a time. I have two branches growing out of the sides and out, then up, and slightly below those two branches are two more growing out and up on the opposite sides. Should I trim that and how?

Thank you

Answer from Gabrielle Harden, USU Forestry Extension Educator (sent 5/27/20) -

One of those lateral branches will eventually replace the central leader that was broken. If the branch to replace it is more lateral than vertical, you may need to assist the process. Select the strongest lateral branch just below where the central leader previously was, then make sure that this selected branch is longer than others. The central leader should typically be at least 15 cm longer than the other branches. Ensure that the previous central leader is pruned back (see fact sheet here about pruning), and if possible, provide a stake for the lateral branch that was chosen to replace the central leader. If the lateral branch is nearly vertical already, a stake isn't really required.
It appears the ideal branch to take over is more lateral than vertical, so a stake would certainly be helpful. Leave it in place for a couple of years (or until the lateral branch takes over as the central leader), but make sure that whatever you use to hold the stake to the tree does not girdle the tree.

I hope this helps