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Question from Frank, UT (received 4/27/20) -

I have a tree in my yard that Rocky Mountain Power wants to top or cut limbs in a L shape away from the power line. This tree is over 50 years old and at least 30 feet high. It is a healthy tree, Cone shaped I believe it of the Juniper family. I am afraid they are going to kill it with this technique. Please can you suggest a trim that would satisfy the utility but not harm my tree.

Answer from Dr. Mike Kuhns, USU Extension Forester and Professor (sent 4/27/20) -

Frank,

Any tree that grows within a certain distance of a powerline must be pruned enough to maintain clearance. The clearance increases with higher voltage, with the lines that supply individual homes within neighborhoods needing much lower clearance than others. Yours might need 15 feet of clearance, but even then, they usually try to get more clearance since as soon as it starts growing again it will be too close.

Even though the L-shaped, V-shaped, and one-sided trees are odd looking, this pruning does not harm the tree as long as branches are removed back to the point that they meet another branch big enough to suppress sprouting and promoted healing. Typically that means that the branch that is removed is at least 1/3 of the diameter of the one that stays. The one that remains also needs to be healthy and vigorous.

I do think that it is good to contact the power company and the contractor doing the pruning and to let them know that you care about your tree and that you will keep an eye on the process. However, I think that it will not harm the tree.