I do not install many cables in trees. I honestly do not believe they really even serve a purpose. When properly installed they may brace the tree a bit and offer some additional support. The theory is that it will help keep the tree from separating as much in the wind. They can also be used to help stiffen up oddly shaped branches and even slightly guide them back into some sort of uniform structure.
I see 80% of cables in trees we work on improperly installed. Cables are only affective in the top 2/3 of the tree. This is where they add the most stability. Cables should be installed about a foot under healthy crotches. They should be as perpendicular as possible. No crazy angles or it will takes away from the strength of the cable. most of the hardware we are going to talk about using is designed to be strongest when pulled straight if that makes sense. There are many different types of cabling systems. The easiest way is to wrap around the part of the tree you are securing the cable to. This method will need to be checked on and adjusted as the tree grows. It can girdle the tree and actually choke the life out of portion above the cable. Another option is drilling through the tree and using lag bolts or some other more sophisticated/expensive system. This is definitely the most secure way that will provide the most strength. It is also the most intrusive, as you are drilling completely through the tree. I do not thin k people realize that these systems both require annual inspections and maybe adjustments. In these two approaches I have seen the long term damage that occurs. The tree tries to compartmentalize around the hole and seal itself off. Often times we have just created a slowly growing problem invites moisture and infestation. I cannot recall one tree I've worked on with cables in it that I thought the cables weren't partially responsible for causing further damage. I always wonder did the cabling help the tree stay up this long or would the tree be in better shape and just fine without the cable. I honestly believe that trees are better off with he less we do to them. Adding metal to a tree never sat right with me.
Now the 3rd option is probably the least affective but also least intrusive. Installing j or eye hooks. The reason that this method is least affective is that the hooks will probably come out and loosen up on their own. Since annual inspection is suggested, then it would not be that big of an issue to monitor and repair the hooks as needed in my opinion. One of the strengths of this system is that the hooks do not set as well. I think is is potentially a plus though. If the tree fails the cable might fail. in this system hopefully the hooks would fail and rip out of the tree. This would in theory minimize the damage to the healthier part of the tree that we are anchoring to.
I think most people assume that cables will prevent sections or trees from completely come crashing down. Cables are strong but not strong enough to support a few 1000 pound piece of tree. This is especially true when the cable is shock loaded. In that scenario tensile strength would be a factor and only give the cable about 1/10 strength to its failure point. When the cables do not fail, in my experience it trashes the rest of the tree and creates a more dangerous situation to deal with.
In conclusion it is important to understand what cables can and cannot do. What they are actually used for and how to properly install them. Also, that they may not actually achieve any unrealistic goals. Annual inspection is suggested and there are no guarantees. They can provide some peace of mind and also knowing that we are trying to take care of our trees as best we can. I have installed one cable in 7 years. I have also turned down about 100 cabling jobs in that time span. One was actually a state record sized Elm tree that I would have love to work on. When it doesn't make sense I will be the first to let a customer know. Almost every tree I have climbed that has cables had unnatural and severe damage as a result from cabling. Tree species can also be a factor in deciding if and what type of cable to install.
There are scenarios where cabling makes sense. I just think it is a lot less common than and unnecessary in most situations. I also do not like how it is promoted so hard. It seems kind of like an added thing that Arborists push to "help" trees. It is kind of expensive and may cause more damage before it does any good. This is one of the reasons I don't fully believe in Arborist certification. This is an experienced based industry and nothing can replace that. I will write another blog about my beliefs on the arborist certification. I am open to any comments on cabling. I love hearing other peoples experiences and am always open to learn more. These are just my opinions based off my life experiences in the tree care industry.
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