You might wonder why anyone would want to go through the trouble and expense of running an unsightly cable through a tree. But there are a few very good reasons why cabling a tree can make sense, including to prevent costly property damage or lawsuits, and to save your investment in a mature tree or to preserve the appearance of a beloved tree.
What Is Cabling?
"Cabling" is the use of cables between limbs or leaders to limit movement and thereby stabilize an established tree growing in a manner that isn't sustainable if left uncorrected. It can be used to save a tree with a split trunk or in danger of developing a split trunk; without cabling, such trunks will eventually be torn apart. Another use of cabling is completely preventive in nature: Cables can support a heavy branch that's growing at an awkward angle.
Benefits to Cabling a Tree
A large tree such as a mature white oak (Quercus alba) or sugar maple (Acer saccharum) situated adjacent to your house has the potential to present a threat to your home. If a heavy branch from the tree looms over your house and there's reason to doubt its stability, cabling is an alternative to having it removed altogether.
Similarly, a heavy, unstable branch overhanging a sidewalk poses a threat to anyone walking under it. You could be sued for injuries if the branch were ever to fall on someone.
But trees can represent more than just threats. Sometimes, we genuinely love a tree and would hate to see it lose a major limb, which would leave it disfigured. A major limb in danger of snapping can sometimes be saved through cabling.
A tree also represents an investment in a landscape that adds real estate value. The first cost comes with the purchase. Depending on the type of tree, on its size, and on where you live, you can easily pay several hundred dollars for it, and that's only the beginning. Years of paying for water, fertilizer, pest control, etc. add to the investment. Losing the tree would mean a financial and aesthetic loss. And you could well lose it if the tree's integrity becomes compromised. Damage to either the trunk or a major branch can provide entry to harmful fungi. In either case, cabling can save the tree.
Before Getting Started
Cabling a mature tree can be complicated, dangerous, difficult work. So you must first determine whether you want to do it yourself or call in professional help. Many homeowners prefer to hire arborists to perform the task.
If cabling isn't done properly, it can cause girdling, which can be fatal to the tree. A professional will know where and how to position the cables properly to avoid girdling. Additionally, as heavy as a large tree and its branches are, there's lots of tension to calculate when altering their structure through cabling. The average homeowner lacks expertise in this area. Finally, often the ideal spot to install a cable on a large tree is high up, and this involves climbing. This is something most homeowners will want to avoid.
Homeowners should restrict their efforts at cabling to small trees. Even then, since the cable must be attached in the upper part of the tree's canopy to stabilize a V-crotch, a ladder would be required. Whenever you're working on a ladder at any significant distance from the ground, such work can be dangerous. At a bare minimum, you need to have someone stabilize the ladder for you while you work. A better option is to hire a professional.
How to Cable a Tree
Traditionally, cabling was achieved by drilling holes in the trunk or branches of a tree, through which you inserted a steel cable. More recently, synthetic cables have been developed, which we use in the project described here. These have two advantages (among others), both of which make the job easier for the do-it-yourselfer: No tools or units of specialized hardware are needed for the installation other than what comes in a tree cabling kit—the easiest way to get the needed supplies; and the procedure isn't invasive (you aren't drilling into the tree).
To address the issue of a narrow V-crotch with synthetic cables, you manipulate the cable to make a loop (through a procedure called "splicing") around first one branch, then the other. An expansion insert is included in each loop to account for future branch growth. Also included in each loop is anti-abrasion hose that reduces rubbing where the loop contacts the tree. A shock absorber is attached for further protection. Once the two loops are in place, uniting the two branches, stability is provided against violent movements caused by high winds, yet the material is flexible enough to afford leeway.
Determine Proper Height to Attach Cable
Find a spot 2/3 of the distance up from the bottom of the V-crotch to the tree's top. At this spot, mark each of the two branches in the V with chalk.
Form First Loop
At this height, form the loop around the first branch. To do this, you feed the expansion insert through one end of cable. Determine length of anti-abrasion hose (it should match the branch's diameter); cut it accordingly. Feed the cable inside anti-abrasion hose. Place the cable around branch and follow the cabling kit's instructions to pull it and "splice" it back into itself. Insert the shock absorber.
Move to Second Branch
Bring the remaining cable to the other branch, creating tension on cable as you go by pulling on it.
Form Second Loop
Form loop for the other branch by repeating the procedure.
Cut Off Excess Cable
If any cable is left over at the end after you've completed the second loop, cut it off.
Follow Up Care for a Cabled Tree
When the cables are properly placed with good supportive tension, the work of a do-it-yourselfer is mostly complete. It is a good idea to check the tree annually, or following any incident of heavy wind or stormy weather to make sure the cables have remained in place and continue to give the necessary support.