Article 8 of 12 from Trees: Dispelling Myths & Misinformation, prepared by the arborists of the Southwest Division of Bartlett Tree Experts as a community education initiative.
Visiting a new residential development with lots of mature trees, an arborist made acquaintance with one of the property owners. The resident expressed his admiration for a tree service whose distinctive work appeared at several of the properties nearby. As a result of their crew’s skill and artistry, passersby could now view from the street the splendor of each home through the “sculpted” trunks and scaffold limbs that were stripped bare of their irksome foliage. To accentuate the trees’ sculpture-like appearance, each branch cut was masterfully executed to be flush against the trunk or limb. Foliage aloft had been left dense to provide shade and that classic “look” that was so desirable.
The arborist offered that such practice was actually not to industry standards and harmful to trees. “But this was a family business, and they’d been doing it this way for three generations,” said the property owner. “Then they’ve been doing it wrong for three generations,” replied the arborist.
The above description of what is acceptable – even desirable – tree pruning is tragically common. Like mulch volcanoes, you see it everywhere. Stripping trees this way is called lion’s-tailing and results in poor branch taper, poor wind load distribution, and higher risk of branch failure. It also deprives the tree of foliage it needs to make its food, so the tree will quickly produce “water sprouts.” Some people see these as proof that such pruning doesn’t hurt a tree because the foliage grows right back. (Sounds logical.) But these shoots signal the tree’s urgent reaction to excessive wounding; they create energy drain, and they form weak attachments to the tree because they form from latent buds.
Flush cuts are also terrible practice. They cut into the branch collar and injure stem tissue. This increases the likelihood of decay. A proper cut is outside the branch collar, but not so far that a stub remains.
A qualified arborist is familiar with the American National Standards Institute (ANSI) standards for tree pruning (and safety). These cover types of pruning based on specific goals, such as crown cleaning, thinning, reduction, and vista pruning. The standards recommend how much foliage one should remove in a session, from where on the tree to remove it, and other correct practices. Any pruning cut is a wound, and mature trees do not respond as well to wounding as younger trees. A good arborist knows why and how to execute these wounds to protect the tree’s biological processes and structural integrity.
A tree is not yard art; it’s a complex, living organism. That means a beautiful tree is a healthy tree, and one that’s retained its dignity by respectful treatment based on informed practice.
In the next article, we’ll return to the ground. We’ve discussed watering newly planted trees, but many homeowners have irrigation systems to sustain their landscapes that include mature trees. Certain pathogenic fungi just love these situations. Stay tuned.