Archive for Thursday, December 27, 2012

Garden Calendar: Give splitting trees a life-support system

December 27, 2012


The practices that could potentially prolong your splitting tree’s life are called cabling, pictured above, bracing and guying.

The practices that could potentially prolong your splitting tree’s life are called cabling, pictured above, bracing and guying.

Maybe you have a tree that is starting to split apart, or one that is still in good order but has some big branches hanging over the house that make you lose a little sleep when ice and wind are in the forecast. Is there anything that can be done to help besides removing the tree altogether? Maybe. The answer depends on tree species, size relative to species, and a good cost-benefit analysis.

The practices that could potentially prolong your splitting tree’s life are called cabling, bracing and guying. All are acceptable support systems when installed properly.

A certified arborist — one who has earned his or her certification with the Kansas Arborists’ Association (KAA) or International Society of Arboriculture (ISA) — may be able to perform this work for you. Extensive research has provided information about the hardware and installation that are most likely to work and least likely to cause more damage to the tree.

By hiring an arborist, you can also avoid having your tree featured in an educational presentation by someone like me. I have a whole folder named “Poor Trees!” with stunning examples of things people have done that someone with a chainsaw will fret about later.

Cables and braces are used when two or more leaders (main stems) are present in a tree instead of the preferred single leader. Some tree species like to grow this way, while others may have multiple leaders as a result of poor pruning practices in the tree’s formative years. Either way, multiple stems are more prone to splitting and breakage than a single stem. Cables connect multiple stems, while bracing rods are typically used just to connect two stems. Guying means to support a branch from the ground or another tree.

A good candidate for cabling or bracing might be an old oak with several large leaders high up in the tree, or a sugar maple that is starting to split between two leaders. For shorter-lived, damage- and decay-proned trees like Bradford pears, redbuds, Siberian elms and silver maples, replacement is simply the better option.

Size is important too, in the sense that you probably do not want to cable a tree that has a lot of growing left to do. A river birch is a good example — this species often grows in clumps and might seem like it could use some extra support. If the tree is still young, however, it would be likely to completely overtake the cables or braces — hiding them from a worker engaged in removal years later and creating serious risk to him or her.

Having an arborist install a cable or brace support system may be more or less expensive than removal and replacement of the tree, but long-term maintenance should also be figured into the cost. Support systems should be inspected annually by an arborist to ensure their functionality, and they can still fail. Also, they are only delaying the inevitable — eventually the tree will still have to be removed.

The International Society of Arboriculture recommends cables and braces to be installed according to a standard called the ANSI (American National Standards Institute) A300. Years of research have gone into determining the best methods for cabling and bracing trees for maximum support and least amount of intrusiveness for the trees. Talk to your favorite certified arborist about it if you think it is an option.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. She can be reached at 843-7058.


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