Proper tree pruning is one of the main things that distinguishes a great and reputable tree service from basic and run of the mill, tree services. The world’s leading authority on tree pruning and all things pertaining to trees, is Dr. Alex Shigo, my personal mentor, friend and teacher. His pioneering arboreal research and tree pruning techniques, along with the numerous books and papers he’s authored, are the worldwide gold standard for Certified Arborists, teachers and reputable tree services. What follows are some of the major points on tree care.
Tree service workers should not remove more than 25 to 30 percent of any trees’ canopy at any one time, as doing so can open up the tree to sun scald and diminish its ability to photosynthesize (the process whereby plants convert the photons from sunlight into chemical energy-sugars, starches, etc.-to feed itself). Over pruning trees can also stress them to the point where they can be more susceptible to pathogens and insects and other harmful elements.
Knowing how, when and exactly where to prune branches is critical to the overall process. In essence, all pruning creates wounds. It’s knowing precisely how and where to prune that makes all the difference to trees in terms of how they heal. Dr. Shigo proved that the old and generally accepted method of ‘flush cuts’ (cutting of branches back to and directly parallel with the trunk, which doesn’t allow for proper healing of the wound), are harmful to trees. Because of his extensive research over many decades, we know that branches should be cut just outside the branch bark collar, which is that slight bulge at the connecting point of each branch to its parent branch or trunk.
Dr. Shigo is responsible for discovering the universally accepted principle of CODIT, which stands for Compartmentalization Of Decay In Trees, which basically states that tree cells form a barrier zone around wounds that serve to protect trees from further decay. Those tree services that understand this principle will render proper care to trees and good, valuable service to their clients.
We also now know that the unsightly act of leaving ‘stubs’ is equally harmful to trees, as well. The ends of the ‘stubs’ do not compartmentalize like a proper cut should and thus become a port of entry for harmful pests, as the tips of the blunt cut tend to rot out and the bark peels away from the stub.
Crown Reduction, or the radical lowering of the Crown or tops of trees, is practiced far too often by tree service companies. Again, we go back to the world’s leading tree authority, Dr. Alex Shigo. He taught us that Crowning, sometimes known as Topping or Hat Racking, is harmful, and sometimes fatal to trees and should be done in only the most necessary of situations, the main one being, safety. Topping or Crowning trees causes excessive sucker growth, opens the tree up to sun scald (just as too many Ultraviolet.Rays are harmful to humans, so too, are they harmful to trees), and otherwise seriously stresses the tree. Topping also destroys the natural shape of the tree forever.
When deciding which tree service to hire, out of the many tree services available, be sure to factor the following into your decision. First and foremost, your tree service specialist should be an ISA Certified Arborist (click the green, Oak Leaf ISA logo on my Biography page for a detailed explanation). Your tree service provider should also be a Licensed Contractor, have liability insurance and be bonded. After you have all these components in place, you may want to check some references of the tree service you’re about to hire.
It’s important to remember that your trees have great economic, emotional and psychic value. Feeling comfortable with your tree service provider and trusting that they will perform the proper procedures as agreed to, is paramount. So interview several and choose your favorite tree service.