Can you recall those days of high school algebra when solving for “x” in complex word problems? “X” was the unknown variable that needed to be found. This thought pops into my mind when driving through my neighborhood observing over-pruned trees, and I ask myself: what were they thinking..were they problem solving for some unknown?
Poor pruning suggests that proper pruning still remains to be an unknown. I have difficulty accepting this when I know that tree workers have the information and tools available to them to solve for “x”. Knowing how much to prune is not a mystery. Alex Shigo, the father of modern tree biology, called it dose (or how much to prune). This is similar to the dose on a pharmaceutical prescription that tells us how much to take and consequences of an over-dose.
We know that trees need leaves for the process of photosynthesis. Removing too much foliage (an over-dose) can severely stress a tree that may lead to infestation by pests and infection by disease. We know that the sugar produced by leaves through the process of photosynthesis is required for defense, growth, cellular metabolism, and reproduction. We also know that large pruning cuts can lead to large cavities in trunks and limbs that can impact the long term structural integrity of a tree. This may result in snapping and failure of these woody stems.
The science and mathematics of tree care may be a turn off to some people because they rely on the aesthetic perspective that encourages them to prune trees. However, beauty is subjective, unscientific, and in the eyes of the beholder. An over-dose in tree care may lead to other problems that can not be undone.
Qualified tree care professionals should know about solving for “x”. Our industry’s Best Management Practices (BMPs) recommends to limit pruning to 25% or less of the total crown in one year unless there are structural defects that warrant more severe pruning. When reducing the size or spread of a tree, BMPs recommend cutting limbs back to an adjacent limb that is 1/2 its size or greater. That helps promote better branch attachment and minimize unsightly stub cutting. (Please note that objectives and guidelines are different for pruning fruit trees and hedges).
If you have a trusted tree worker, I encourage you to ask them pruning questions about BMPs. Perhaps this challenge will encourage he/she to get involved in our industry’s professional organizations that are open to everyone.
With encouragement and interest from tree owners, hopefully our trees will be better taken care of, which can add to the property value and enhance tree related benefits.
If your tree trimmer is unaware of where to start, send he or she my way. I can help.
Or go online to www.isa-arbor.com
Solving for “x” in tree care should no longer be an unknown.
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