What is girdling a tree?

How to Save a Girdled Tree

by Ruth Ann Grissom

June 5, 2018

I saw it coming. I knew the tree was going to die, sooner rather than later, but I didn’t do anything to save it. Every time I saw the cable wrapped around that oak, I’d throw up my hands and think, Too late now! (A phrase made famous in our family by my husband’s father, which I jokingly attribute to his Sicilian fatalism.) For years, the oak has anchored one end of a cable we’d strung to serve as a gate. As the trunk expanded, it bulged around the cable. The oak had slowly succumbed to strangulation. Last spring, it didn’t leaf out. Now, poison ivy creeps up the trunk, hiding my shame.

To appreciate the damage wrought by a tight constriction, it helps to understand a tree’s vascular system. The outer bark protects the tree from external stressors such as predators and fire. Underneath, there’s a layer called the inner bark or phloem. Here, sap flows down from the leaves, supplying the branches, trunk and roots with sugars and nutrients. Next comes the microscopic cambium, a thin layer of growth cells. Deeper into the trunk, there’s a layer known as sapwood or xylem which houses the thick-walled cells that transport water and minerals up from the roots. At its center, a tree is composed of dead heartwood.

A tight cable eventually cuts off the flow of water and nutrients. The tree’s very growth leads to its demise. It’s a slow decline. A tree’s canopy might thin out over the course of several years. A diminishing supply of water and nutrients mean the tree is unable to produce as many leaves. This becomes a death spiral as the tree becomes increasingly unable to supply nutrients to the roots.

A tree can usually survive if less than half its circumference is girdled. Even so, the area with the embedded material is weak and susceptible to breaking. The trunk can snap during an ice or wind event.

The other end of our cable is attached to a cedar. Fortunately, it hadn’t embedded yet. We loosened it and moved it a little lower, buying us a little more time. We really need to get organized and update our method of attachment. Now, when we put up a gate and it isn’t feasible to set a post, we bore a hole through the trunk and fasten the cable with a bolt. It sounds terribly invasive, but it’s easier for a tree to heal around a single point. This approach can be used for semi-permanent structures such as deer stands, tree houses, zip lines, hammocks and gates.

Problems can also arise when temporary structures such as Slacker lines and supports aren’t removed in a timely manner. Newly planted trees generally need to be staked for no more than a year. A little movement actually promotes root growth.

On occasion, a tree can be girdled if it hasn’t been properly sited. I recently ran across a truly bizarre example in my neighborhood. A crape myrtle in the planting strip grew around an electrical guy-wire and then a willow oak grew around them both. At some point, the crape myrtle had been cut, leaving stumps of mottled bark sticking out of the willow oak’s trunk. The guy-wire pierces both. Near the end that’s anchored in the ground, the crape myrtle’s bark protrudes around it like a pouty lip. The wire emerges, perfectly centered, farther up the willow oak’s trunk. This situation didn’t end well for the crape myrtle, and it doesn’t bode well for the oak.

Bridge grafting is an excruciating, last-ditch approach to save a girdled tree. First, the constricted section of bark is cut away. Strips of wood are taken from a branch and cut to lengths slightly longer than the gap. These strips are then inserted under each edge of the healthy bark, theoretically reestablishing the flow of nutrients and water. Think of it as bypass surgery for a tree. It doesn’t always work, and it certainly isn’t attractive. The best course of action is to follow some wise advice – an ounce of prevention is worth a pound of cure.

To learn more, see How a Tree Works

and 24 Ways to Kill a Tree



Tree Girdling Technique: Learn About Girdling For Fruit Production

Girdling a tree is often on the list of actions to avoid in your garden. While stripping bark off a tree trunk all the way around is likely to kill the tree, you can use a specific tree girdling technique to increase fruit yield in a few species. Girdling for fruit production is a frequently used technique on peach and nectarine trees. Should you girdle fruit trees? Read on for more information about tree girdling techniques.

What is Tree Girdling?

Tree girdling for fruit production is an accepted practice in commercial peach and nectarine production. Girdling involves cutting out a thin strip of bark from around the trunk or branches. You have to use a special girdling knife and make sure you don’t cut deeper than the cambium layer, the layer of wood just under the bark.

This type of girdling interrupts the flow of carbohydrates down the tree, making more food available for fruit growth. The technique should only be used for certain fruit trees.

Why Should You Girdle Fruit Trees?

Don’t start girdling fruit trees randomly or without learning the proper tree girdling technique. Girdling the wrong trees or the wrong way can kill a tree quickly. Experts recommend girdling a tree to enhance fruit production only for two types of fruit trees. These are peach and nectarine trees.

Girdling for fruit production can result in bigger peaches and nectarines, more fruit per tree, and an earlier harvest. In fact, you may be able to start harvesting fruit 10 days earlier than if you don’t use this tree girdling technique.

Although many home gardeners do not perform girdling for fruit production, it is a standard practice for commercial producers. You can try these tree girdling techniques without damaging your trees if you proceed with caution.

Tree Girdling Techniques

In general, this form of girdling is done about 4 to 8 weeks prior to harvest. Earlier varieties may need to be done 4 weeks after blooming, which is about 4 weeks before their normal harvest. Also, it is advised that you not thin peach or nectarine fruit and girdle the trees simultaneously. Instead, allow at least 4-5 days between the two.

You’ll need to use special tree girdling knives if you are girdling for fruit production. The knives remove a very thin strip of bark.

You only want to girdle tree branches that are at least 2 inches (5 cm.) in diameter where they attach to the tree trunk. Cut the girdle in an “S” shape. The beginning and ending cuts should never be connected, but finish about an inch (2.5 cm.) apart.

Do not girdle trees until they are four years old or older. Pick your timing carefully. You should perform the tree girdling technique before pit-hardening during April and May (in the U.S.).

By Anupum Pant

Background

Of course, killing a tree is something I’d never want to do. I see them as old and wise people who have grown and matured for years. Plus they give us so much in return. And yet sometimes, they say, there are good reasons to kill a tree. I’ll probably never understand.

Anyway, I thought it’s good to know, just for the sake of knowing that there is an incredibly simple technique that is often used to kill trees (for legit reasons) and is widely known among horticulturists. I learnt about it just today, and I felt it was worth sharing.

It’s called Girdling (also known as ring barking or ring-barking). Or, a technique which involves removal / peeling of a ring of bark from a tree, and the phloem layer (Like shown in the picture above). Yes, that’s it, this kills a tree. And it’s slow death. A tree which gets girdled dies gradually in about a year or more.

This is why it works…

The central part of the tree trunk (wooden part) is involved in taking the nutrients and water up to the leaves. The leaves then get exposed in the sun and mix in carbon dioxide to make sugar and other reduced carbon compounds. Most of us know that. But this is what not many know…

The outer part of the trunk – the bark and the phloem layer – also has a solid function that sustains growth and function. It’s responsible to carry the sugar (and other stuff) made by the leaves, back to the root. That is basically food to sustain growth and function of the roots. If that doesn’t reach the roots, the roots don’t receive what is required for their growth and function. Girdling does exactly that – cuts off the down-flow of food. As a result, the root dies and with it dies the whole tree. All of this happens very slowly.

To be noted

Jumping the Girdle: Some times, trees are able to repair this damage. It’s called a jumped girdle. To prevent that from happening, often smear herbicide over the girdled area.

Better Fruits: This technique is also used by some farmers to force the tree to bear better fruits – as no sugar goes down into the roots – the fruits are usually bigger and better if they come from a girdled tree. Of course these better fruits come with a price.

Girdling is particularly a good way to end trees like Aspens because as we know from Pando, many other Aspens can sprout up from the roots and cause a bigger mess if just the top part of this tree is cut off.

Girdling is a better way to kill a tree because it gives the environment time to adjust, also it is cheaper and prevents damage to the other delicate plants around the tree.

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