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Loose Bark and Tree Trunk Damage
By John Fulton

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[October 16, 2015]  Many have been complaining about loose bark on tree trunks and limbs. First off, bark is dead. It is a protective covering, but not necessarily essential to the livelihood of your tree.

As tree trunks and limbs grow, they naturally shed bark and new bark is formed. Usually this is in small pieces that don’t grab your attention, but as an example sycamore trees tend to shed bark in large strips.

Rather than a tree loosing bark in a large patch, the real concern is probably what caused that to happen all at once. In many cases, this is caused by one section of the tree trunk growing and the remainder of the trunk not growing. The expansion of the growing area means the bark gets loose at the edge of that area. After a while, it simply becomes loose and falls off. Unfortunately, the area not growing is usually a dead area.

Dead areas on tree trunks come from many causes, with many of them being a form of mechanical damage. Think of a mower scrape, weedeater injury, bicycle rub, or transplanter damage as mechanical. You can also throw chewing from four legged creatures into the mix. Rabbits or mice chewing on trees can cause dead areas. Same goes for rubbing whether from deer or other branches being whipped by the wind. Areas may also be affected by fungi, bacteria, and insects.

The one thing to keep in mind is that dead means dead. It won’t miraculously go away. What the tree tries to do to compensate is to heal around the dead area. This is evident with what is called callus tissue. It is relatively smooth, and tends to “roll” from the good wood until it covers the affected area. Once completely covered, the outside looks “healed,” but the inside part will still have the dead area contained in it. Dead trunk areas frequently affect upper limbs, due to loss of tissue which would have carried water and nutrients.

When evaluating what to do with a trunk injury area, it is important to follow a few guidelines. Determine the extent of the dead area. It the area is a significant amount of the tree trunk, it may lead to safety concerns for people and property. Is it dead and solid, or is it also decaying? Decayed areas affect the integrity of what is there, and may enlarge the affected area.

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To do an assessment, you can use something pointed (ice pick, awl, or small Phillips screwdriver) to determine if there is decay. To assess the depth, you can actually use a drill and bit to see how far in the dead area goes. A rough assessment can be made by seeing where the callus tissue begins on either side of the wound. 

Location, extent of damage, and the offsetting benefits of leaving a tree all go into the decision to remove or leave it. Severely damaged trees adjacent to homes, buildings, and vehicles should probably be removed. A severely damaged tree which would not hit anything if it falls, is easier to leave. This gets a little trickier if there is potential for damage, but the tree is the only shade you have for the patio. If you decide to leave the tree, remove decayed material. Sometimes filling larger voids with items ranging from plaster of Paris to bricks and mortar is done – just remember where construction was done if you have to cut the tree down at some point. Then, paint dead areas with an exterior latex paint to discourage insects such as carpenter ants.

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]

 

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