Correct tree trimming requires set of principles

A June 15 letter writer is misled to think topping trees makes them safe. Quite the contrary. Topping makes trees unsafe for two primary reasons:

* A limb cut mid-branch does not grow back another limb. Instead, excessive hazardous sprouting occurs. Many sprouts are weakly attached to the bark (instead of the branch interior) and easily detach or break in the wind.

* Sprouts grow excessively, causing overcrowding that blocks the sun from reaching leaves and photosynthesizing to make sugar. Dead sprouts fall onto whatever unfortunate thing lies below, and make a big mess to rake up. Topping makes trees more culpable to falling because wind cannot pass through the dense crown of sprouts. Conversely, the International Society of Arboriculture prescribes thinning out interiors by removing deadwood and unnecessary multiples.

The premise that stumping trees prevents branches from impeding movement is untrue. Low cuts form branches beneath them, increasing low-lying growth. ISA prescribes “raising the crown” by removing low branches at their origin.

A certified arborist (or any tree trimmer) might not follow certified arborist principles, especially when a customer requests otherwise. I encourage every property overseer to require their tree trimmers to acquire and follow ISA principles, and everyone to read the ISA TreesAreGood website to know whether trimmers are applying ISA principles and whether you are getting your money’s worth.

Jean A. Pezzoli

Member, County Arborist Committee

Former president, Maui Outdoor Circle