Q.Should we trim lower branches in a maple tree that are growing horizontally?
Our young maple tree lost its center trunk this winter. There are 4-5 main beaches left. One of the 5 is starting to look like it is going to take the center branches place. The potential problem is the other 4 main branches are growing horizontal. Do we trim those 4 horizontal branches?
Yes, you should reduce the horizontal branches by pruning off 1/4 to 1/3 of the length at this time. During dormancy you may choose reduce a little more.
Let the new developing central leader do its thing, until it appears to be excessively tall and not branching and in danger of leaning and breaking. You can snip a few inches to suppress apical dominance and re-direct slightly into a "modified central leader".