Tree topping: By tree topping I do not mean the appropriate pruning practices that trained arborists may employ (such as with fruit trees or broadleaved street trees). Rather, I mean the cutting off of the top of a tree to improve views or avoid power lines.
Tree topping is actually one of the most common things I get asked about as an Extension Forester. Is it OK? Will it hurt the tree? My advice on tree topping is simply this: Don’t do it. In fact, I can only think of one legitimate reason to top a tree, and that is to create a snag or wildlife tree.
Topping is one technique to artificially create a snag. Why? Because it’s so effective for killing the tree. Not only has the tree lost its leader and a key portion of its photosynthesis factory, but now you have a nice fresh cut across the top of the stem that is exposed to the elements, collects rainwater, and otherwise fosters the perfect conditions to introduce disease and decay right into the stem of the tree. This is great if you want heart rot for cavity dwellers or to have a dead or malformed tree to provide habitat features. Not so good if you want a tree that looks good or is healthy.
Think about a tree or trees in your forest that have been naturally topped (e.g. top blown out by wind, snow, or ice). What does the tree look like now? What were the impacts of the storm damage to the tree’s appearance, growth, health, and vitality?
There are bound to be conflicts between trees and either views or power lines. In these cases, I do not believe that topping is the answer. In the case of power lines, you may be able to work with your power company to identify the most likely hazard areas and do some careful branch pruning without simply hacking the top off of the tree.
If the conflict with the top of the tree is unavoidable, then the problem is ultimately that it is the wrong tree for that location. In this case, I recommend removing the tree altogether rather than keeping it in a ruined form by topping. You can replace the tree with a smaller variety that won’t cause problems, or leave that particular area tree-free.By Kevin W. Zobrist, Washington State University Extension