Today, we wanted to talk about an avoidable, but all too common, threat to your trees: girdling. Girdling occurs when something wraps around a tree branch or trunk, and causes damage to the tree’s vascular tissue. Severe girdling damage often leads to the death of the affected branch, if not the entire tree.
We spoke about girdling roots in a previous post, and the same basic principles are at play. The primary distinction between girdling roots and the type of girdling we are discussing today is the offending item. Whereas girdling roots grow around the trunk, accidental girdling often occurs courtesy of stake wires and other forms of cordage tied to a tree.
Nature of the Problem
We have discussed the nature of the problem in the girdling roots posts, so we will not go into great depth here.
Trees transport water from the roots, through the trunk, and ultimately to the leaves via the xylem (wood) tissue. Conversely, the sugars produced in the leaves are transported down the branches, through the trunk and into the roots via the phloem tissue. This phloem tissue lies just inside the bark tissue, right outside the cambium layer, which separates the phloem from the xylem.
Wrap something tightly around a trunk or branch, and the phloem can sustain damage. This damage prevents the movement of sugars, which stresses the tree (to put it mildly). A little while later, the tree goes into decline and usually dies in short order. The technique kills trees so dependably that it is often used to kill trees deliberately.
Many trees are inadvertently girdled by human activities. Someone ties something to a branch or trunk, fails to remove it quickly enough and ends up causing harm. Although it is obviously a practice to be avoided, the reasons it is such a common occurrence are understandable. After all, trees make great anchors for everything from clotheslines to rope swings, and people get busy and forget things – like re-attaching clotheslines and rope swings on a regular basis.
Some of the most common applications that lead to girdled trees include:
- Tree Staking – Also called guying, tree staking involves attaching a stake to a flexible cord, which is then wrapped around a tree’s trunk to keep it stable and offer some degree of protection. The ins and outs of staking are complex, and while they are not advisable in all circumstances, they are helpful in some situations. Among other potential problems, improperly applied cords may end up girdling the tree. Nevertheless, appropriate application and regular inspection can help insure that the tree does not suffer an injury. Most stakes should be removed after no more than one year, and they should be inspected at least once every three or four months.
- Swings and Other Hanging Things – In the right circumstances, trees can provide anchor points for swings and other items. Aside from the obvious need for careful planning, it is important to attach these types of things to the tree in a manner that will not result in girdling. Every circumstance is different, but following a few general principles can help reduce the damage to the tree. Periodically moving the suspended item from one place to the next can help allow the tree to heal, and cushioning the attachment point with soft materials can help reduce the damage in the first place.
- Unusual Items -- Just about anything can girdle a tree. Ropes, twines and other forms of cordage can lead to girdling, but occasionally, other items cause similar damage. For example, trees growing too close to fences (particularly barbed wire fences) can become damaged as the tree’s growth causes the barbed wire to be pushed into the bark. Often, the damage only affects part of the tree, but even partially girdled trees become more likely to fail.
To avoid these types of problems, ensure that fences and other items give the nearby trees enough room. If a conflict between the two is unavoidable, it is preferable to redesign the fence or remove the tree proactively.
Do not hesitate to ask questions or join the discussion in the comment section. In addition, fellow tree pros should share some of the craziest things they have found girdling trees!