Question
When can I trim my Sunburst Locus tree, It it quite tall the bottom branches are running into the Bridal Wreath
Spirea. I want to cut it back some but am not sure when.
I live in Halifax. Nova Scotia.

Answer
The best time to prune locust is September and October.
Prune the limbs back to the trunk.  Pruning cuts should be made just outside the branch collar. The branch collar contains trunk or parent branch tissue and should not be damaged or removed. If the trunk collar has grown out on a dead limb to be removed, make the cut just beyond the collar. Do not cut the collar.

If a large limb is to be removed, its weight should first be reduced. This is done by making an undercut about 12 to 18 inches from the limbs point of attachment. Make a second cut from the top, directly above or a few inches farther out on the limb. Doing so removes the limb, leaving the 12- to 18-inch stub. Remove the stub by cutting back to the branch collar. This technique reduces the possibility of tearing the bark.
Do not use a wound dressing on the cut the tree will heal faster without the dressing.