It happens. When trees are not properly pruned or trained when they’re young, they can grow in such a way that they simply cannot support their own weight. Mature multi-trunked trees are particularly susceptible to this condition, as are open-canopied trees with limbs that grow horizontally or downward. Additionally, newly-planted trees can sometimes be weak-trunked or unstable, caused by close planting in the nursery, inadequate root balls, root damage, or planting in too-shallow holes or compacted soils.
Tree-support systems — cabling, bracing, guy-wiring, and staking — can be appropriate remedies for structural deficiencies and instability. When applied and maintained correctly by certified arborists, these support systems can prevent the failure of a trunk or limb, protect property or people, extend the life of the tree, and provide added stability to newly-transplanted trees while they build supportive root systems.
It’s important to know that arborists make decisions very carefully about whether and how to install support devices. These mechanisms support the tree by limiting the movement of branches or leaders, or providing extra support to weak areas of the tree. As such, support hardware is also intrusive and restrictive for the tree. So in determining the best course of action for an ailing tree, professionals weigh the risks and rewards. They also assess whether a tree is simply beyond help and should be removed.
Cabling and Bracing. Cabling and bracing are the most commonly-used tools to protect or improve a tree’s structural integrity.
- Cabling reduces the risk of breaking or splitting by restricting the distance branches or co-dominant trunks can move in relation to the rest of the tree. The cables are typically installed in the upper crown or across a weak crotch. Traditional static cabling systems are made from high-strength, long-lasting steel wire and hardware, and allow for very little movement in the tree. The newer dynamic cabling systems are made from synthetic fabric roping and sling attachments; the “give” in the dynamic cabling allows for more natural movement in the tree. Your arborist can determine which type of system is best suited to the needs of your tree and property.
- Bracing rods are installed in trees with multiple trunks (co-dominant “leaders”) to reduce the risk of the leaders splitting or to repair splits that have already occurred. The rod is installed as a “through-rod” (rod is bolted with a nut on other side of tree or branch) or “dead-end” (rod is threaded into the tree). Bracing rods are typically used along with cables.
Guy-wiring and Staking. Staking or guying systems are sometimes used on a newly-planted tree to give added reinforcement while it establishes enough of a root system to stand on its own. Guying and staking systems should only be used when necessary, and for the shortest time possible. Since stakes or wires require some sort of strapping device to tether them to the tree, the chance of injury to the tree increases with the length of time the devices are attached. Staking and guy-wiring should also allow for some degree of movement in the young tree. Why? When a tree is allowed to sway in the wind, it actually lays down important structural fibers at the base of the trunk.
- Guying involves attaching three or four wires to the tree and anchoring them to the ground in order to provide extra support and reduce the tree’s movement. (Many of us do annual guy-wiring on our indoor Christmas trees!)
- Staking is when rigid stakes (plastic or wood) are tied to a young tree’s trunk to hold the tree upright and the root ball in place, or to straighten the trunk. It’s fair to say that staking is the least-favorite support system among tree professionals. There is potential for the stakes or ties to grind against the trunk, and staking allows for relatively little of the natural swaying a tree needs to grow stronger.
Only a qualified arborist should install tree support systems. The arborist can determine the best support method, select the right materials, and install the system using the most effective and least damaging techniques. Just as importantly, your arborist can inspect, adjust, and maintain the system regularly to maximize the benefit to your tree.
“Cabling and Bracing,” University of Massachusetts, Urban Tree Program, Accessed May 30, 2017, http://www.umass.edu/urbantree/factsheets/36cablingandbracing.html
Ginny Meade and David Hensley, “Staking and Guying Newly Planted Trees,” Cooperative Extension Service, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, June 1998, https://www.ctahr.hawaii.edu/oc/freepubs/pdf/L-7.pdf
Andreas Roloff, Urban Tree Management: For the Sustainable Development of Green Cities, pp. 141-143, John Wiley & Sons, November, 2015.
David S. Vandergriff and Wayne K. Clatterbuck, “Cabling, Bracing and Other Support Systems for Trees,” University of Tennessee Extension, September 2005, https://extension.tennessee.edu/publications/Documents/SP659.pdf