The purpose of tree cabling is to stabilize limbs on healthy or unhealthy trees using cables to improve structural integrity. Tree cabling is practiced on trees that have not had proper pruning in their developmental years, causing limbs to be weak, heavy, widely spread, or grow at abnormal angles. The cables are placed within the canopy of trees and hold together or separate limbs apart. Cabling is an alternative to removing trees, thus allowing the tree continued growth with extra support while reducing the chance of structural failure. An arborist will be able to determine the correct cabling system to use and accurately position the cables on the tree, or if bracing should be implemented. Furthermore, it is recommended that the cables should be inspected to ensure that the installed cable is functioning properly.
There are three major reasons to perform tree cabling which include promoting tree health, improving tree appearance, and averting property damage. It is possible that split trunks or open wounds as a result of unhealed pruning wounds or winterization cracks will attract insects or fungi, causing the tree to decline if inhabited. Additionally, moisture entering the opened area could lead to decay. If the split or open area were to be cabled closed, this could increase the lifespan of the tree. Cabling also helps to improve the appearance of trees with multiple trunks or lopsided trees, resulting in increased property value. Furthermore, to prevent any damage to homes, property, cars, or people over-extended or heavy limbs can be cabled instead of removed. It is also possible to both cable and prune trees. For example, if over-extended or heavy limbs are pruned, this will reduce the amount of weight that the cable has to support and will help extend its durability over time.
There are two types of tree cables that arborists use to support trees. The first includes the Cobra Cable System. The cables in this system are made of flexible rope-like cables. This style of cabling supports trees in a non-invasive and natural manner as the cables are relatively loose to encourage self-supportive growth. Cobra cables have shock-absorbing qualities that allow tree canopies to naturally move with wind or ice build-up yet are restrained enough to prevent flailing during extreme weather. The cables are also self-adjusting so the tree will not be squeezed or damaged as it grows in diameter. Homeowners often choose the cobra cable system to support their trees, as it is effective and less costly. For added support to a failing tree, arborists can double the amount of cables used.
The second type of cabling includes the Steele Cable System. This system involves installing hardware into trees and is mainly used by arborists on trees that are large, stiff, or in close proximity to buildings to prevent any potential movement. Since these cables are static, this limits the tree’s natural canopy sway. While this system provides more rigid and stronger support for limbs or cracks, it is also more challenging to install and is more expensive.
Tree bracing is another route for tree support. To brace a tree, a steel rod would be installed through or near the split area of the tree. Similar to cabling, bracing is recommended for trees that have multiple stems or leaders, splits in trunks, or weak branches to prevent further spreading. Depending on the size of the wound and tree, several bracing rods could be installed. To further support trees, braces and cables could be installed collectively.
After installation, it is important to annually inspect the cable for tangling between branches and cables or cables that have become stressed by tree growth. As time passes and tree growth continues, the originally installed cables will not be as supportive as they once were especially if they remain in the same location. While cables can last physically for roughly 50 years, they should be replaced in a different location on the tree every 10-15 years, thus supporting the changes in weight distribution.