Trees in the forest do quite well with just a little help from nature. That isn’t quite the case for the landscape trees that surround our homes and beautify the Conejo Valley’s streets and boulevards. Landscape trees require a more stringent level of maintenance to keep their beauty and structural integrity. The simplest description of the maintenance required is simple pruning, but that hardly captures the complexity required to prune properly, beginning with an understanding of tree biology.
In the coming months we’ll look at the ABC’s of pruning properly, but this month we’d like to comment on the most common form of improper pruning — tree topping.
According to the International Society of Aboriculture (ISA), “Topping is perhaps the most harmful tree pruning practice known.” That’s why the ISA has for over 25 years published brochures and pamphlets, and conducted seminars, getting the word out about why topping can harm your trees.
First, a clarification. Exactly what is topping? The ISA describes it as “the indiscriminate cutting of tree branches to stubs or to lateral branches that are not large enough to assume the terminal role.” That’s quite a mouthful, but it basically means that proper pruning of small branches involves simply cut back to where they branch off the main trunk. Larger limbs are a little trickier. If it must be shortened, it should be cut back to a lateral branch that is at least one-third the diameter of the branch being shortened. The remaining branch then has what is called a “terminal role.” The goal of this approach, along with maintaining the tree’s health, it to preserve the tree’s natural form.
Sometimes rather aggressive pruning is necessary — for example, when the tree is intruding utility lines. But if that aggressive pruning involves large cuts, the tree may not be able to close over the cut. In that case, your arborist needs to determine if the tree should be removed and replaced as the best alternative.
The ISA has good information on tree pruning in general here.
You may also download a PDF on why Tree Topping hurts here — it gives the full story on why tree topping should be avoided.
If you’d like a consultation about a tree in your yard that needs to be trimmed, either normally or aggressively, give us a call. We’ll let you know what your best options are.