Girdling very dangerous for trees and branches
In the fashion world, a girdle is outmoded and slightly funny. For a tree, girdling is no joke.
To girdle a tree is to damage the bark and underlying tissue all around the trunk or a branch, killing it.
“The vessels that carry water up and down a tree are just beneath the bark,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at the Morton Arboretum in Lisle. “If you damage those vessels, you’ve cut off the water flow.”
“It may take a while for the whole tree to die back, but it’s a deadly injury. A tree can’t recover from girdling.”
In fact, when land managers need to kill a tree — for example, to battle invasive species — they often deliberately girdle it by cutting away a band of bark all around the trunk. The term comes from an Old English word referring to a band or belt.
There are many ways homeowners and contractors can inadvertently girdle trees or branches, Yiesla said.
Tying ropes or wires around trees. If an encircling rope that held a hammock, a sign or tree stake isn’t removed, it will start to cut into the bark as the trunk grows. Eventually it will sever the water vessels and girdle the tree. The same thing can happen to a branch if a swing is tied to it with ropes.
Hitting trees with power tools. Lawnmowers or string trimmers that chop at the base of a tree can damage the bark all the way around, girdling the tree. To keep power tools well away, spread a safety zone of mulch.
Not removing ropes and wires at planting. Some trees are transplanted with their root balls bound by wire baskets or ropes. If those wires or ropes are not removed at planting, they can eventually girdle the tree.
A tree also can girdle itself when a root encircles the trunk. As the trunk expands, the root will constrict it and kill off the bark. “It’s self-strangulation,” Yiesla said.
This can happen when a tree is growing in a constricted space where there’s not enough room for its roots, such as a parkway. Some species, such as Norway maple, are especially prone to girdling roots. Girdling roots also can develop if a young tree is grown in a container with roots circling inside. “If you find that you bought a tree with circling roots, be sure to spread the roots out using your fingers when you go to plant,” Yiesla said.
If a tree or branch seems to be dying back, girdling is a likely cause. “Check to be sure that the bark is undamaged all the way around so water can flow,” Yiesla said. “Throughout the tree’s life, make it a priority to protect the bark from girdling.”
For tree and plant advice, contact the Arboretum’s Plant Clinic (630-719-2424) or plantclinic@mortonarb .org).