Proper pruning
By Zenaida Serrano
A cut should be made just outside the branch bark ridge and the branch collar, leaving the collar intact. That seals off the wound and prevents rot. If a large limb is to be removed, its weight should be reduced using the three-cut method. This lowers the risk of tearing the bark. 1. Make an undercut — not all the way through — about 12 to 18 inches from the limb's point of attachment. 2. Make a second cut from the top, directly above the undercut or a few inches farther out, to remove the limb, leaving the 12-to-18-inch stub. 3. Remove the stub by cutting back to the branch collar, leaving collar intact. Source: Trees of Hawai'i Inc. The Outdoor Circle Jeff Widener | The Honolulu Advertiser
So the Manoa resident, 59, is mindful of properly maintaining and pruning his trees, some of which are growing just yards away from his home.
"I'm not an expert, but I do have a lot of experience in the yard," said the pediatrician, who devotes at least four days a week to doing yard work. "There are right and wrong ways to prune a tree, and it's important to cut a branch correctly."
Lam is among thousands of Hawai'i homeowners who have trees, many of which require periodic trimming. But pruning doesn't involve simply hacking away at lengthy branches. In fact, improper pruning may weaken a tree's structure, making it a potential hazard, and can ultimately kill a tree, experts say.
"Ninety percent of our trees in the urban setting are destroyed from improper pruning," said Abner Undan, an arborist and president of Trees of Hawai'i, a company that maintains trees and removes defective or structurally compromised trees.
"We'd like to see it done right," said Mary Steiner, CEO of The Outdoor Circle, a statewide environmental organization and advocate for Hawai'i's trees. "Trees add tremendous value to our environment, as well as to our economy."
Often those unfamiliar with how to correctly trim branches end up "topping" their tree — cutting a tree's large branches and main stem of its crown.
"Topping is considered the worst type of pruning method that one can employ to a tree," Undan said.
Other pruning mistakes include cutting branches too close to the trunk or to the point of attachment.
CHOP TALK
Advertiser Staff Writer
Jeremy Lam's yard includes a forest of kukui nut, mango, lychee and false wiliwili trees, as well as three giant shower trees, each of which towers past 20 feet.
Arborist Abner Undan prunes dead branches from a mountain apple tree at the city nursery on Pali Highway. That will allow more air and light to reach inner areas of the tree. If a tree's live branches are crowding each other, some of those should be pruned as well.
MAKING THE RIGHT CUT
Severe topping can trigger a massive growth spurt instead of curbing the tree's height. Or the hacking may weaken and even kill the tree.
Clip small trees — such as this lemon tree at the city nursery — with shears or a small saw. Experts advise never using a machete.
"One of the problems of too many homeowners is that they think trees require annual pruning," Undan said. "Some trees don't require (that)."
So how does one know when it's time for a trim?
That depends on what you want to accomplish, Undan said.
"Some people prune trees simply because they think that tall trees are dangerous trees, so they go ahead and top trees," Undan said. "That's not the solution."
Topping a tree triggers a massive regrowth, he said.
"In a year or so, that tree will be even taller than before you pruned it," Undan said.
Before trimming a tree, Undan recommends homeowners ask themselves why they want to do it.
Is the tree too tall? Is it too low? Are there any dead branches? Any broken branches?
"If none of those exist, chances are they don't need to prune the tree," Undan said.
Trees should be pruned to remove dead or crowded branches, to increase light and air penetration, to develop a stronger structure or to reduce potential hazards, experts say.
Lam, the Manoa green thumb, trims back the smaller branches of his kukui nut tree only when they begin to reach his home.
"For bigger projects, like shaping my mango or lychee trees, I hire a professional," Lam said.
One of the most common reasons for pruning is to adjust or maintain the height of a tree, Undan said.
Homeowners should determine the desired mature height of their tree, whether it's 10, 15, 20 feet or more. As soon as the tree reaches that height, any growth beyond that should be cut. Long branches should be cut to a suitable lateral branch; in other words, to at least one-third the size of the branch being cut, Undan said.
"But don't create stubs," he said. "You always cut (the branch) to the next lower lateral."
Continue to do that annually, if not more often, until the tree adjusts to the desired height.
"If you were to regularly do that, the tendency of the tree is to form a wider crown, rather than a tall crown," Undan said.
MAKING THE CUT
Whether you've got mango, tangerine or lychee trees in your backyard, the general rules for proper pruning apply to them all, Undan said. (See box.)
When a tree branches, it forms a branch bark ridge and a branch collar.
The branch bark ridge is the slightly raised bark area between the branch and the main trunk or main branch. The branch collar is the swollen portion at the base of the branch, where it connects to the main trunk or main branch.
A cut should be made just outside the branch bark ridge and the branch collar, leaving intact the collar. That seals off the wound and prevents rot, Undan said.
Another important consideration: The leaves or branches that you remove should not exceed 20 percent to 25 percent of the tree's crown, Undan said.
Keeping these pruning rules in mind will help assure the health and longevity of a tree, Undan said.
"There's only one way to prune a tree, and that's to prune it properly," he said.
