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Cavity Fill By Affordable Arbor Care - Your Tree Company in Orlando!

Tree Cavities: To Fill Or Not To Fill

Tree Cavities

A tree cavity is similar to a tooth cavity in that if it is left untreated with the proper treatment, the cavity can only get worse.  In simple terms, a tree cavity is a neglected bark injury that can be the result of many factors. The most common are improper pruning, mechanical injury and storm damage.

Trees planted in urban or suburban areas are more likely to incur wounds and decay rather than trees in forests naturally grown as humans cause the most injury to trees. Although, most of these wounds are unintentional, such as lawn mowers, automobiles, construction equipment or improper pruning. Naturally occurring events such as storm damage, fire and injury from birds and animals can also contribute to bark injury by tearing at the tree trunk. When a bark injury has occurred, the exposed sapwood or heartwood is more vulnerable to attack by fungi that initiates the decaying process.

Many various insects and animals such as raccoons, woodpeckers and squirrels that often inhabit tree cavities utilize the tree wound as their front door. On particular insect, Carpenter ants will channel tunnels throughout the tree and while doing so, they will excrete wood preserving enzymes. While these preservatives they excrete are beneficial to the tree, the tunnels the ants create allow water to accumulate from rain or moisture in the environment and excess water can ultimately result in wood rot.

Fallen Laurel Oak due to Cavity near root base

Trunk wounds that penetrate the bark will damage the cambium layer, a thin layer of vascular tissue, which is vital to movement of water and nutrients. If less than 25% of the bark around the trunk has been damaged, the tree will probably recover. When fresh wounds occur on the trunk, the injured bark should be removed carefully, leaving healthy bark that is sound and tight to the wood. A wound dressing (or spray) is not necessary. You will be able to observe the wound closing from the edges each year as the tree grows. When an older wound is discovered, remove the dried and loose bark back to the area where the new wood can be seen along the edges of the wound. Trunk wounds that are not addressed could potentially be a hazard in the future.

Once a wound occurs, decay-causing fungi can enter the heartwood and the decay process begins. Trees have a natural defense. The wood around the wound begins to produce special compounds in the wood cells that set up a wall or barrier to isolate the infected area. This is called compartmentalization. Recent research shows that it is better to leave the cavity open and take the necessary measures required to improve the overall health of the tree. A healthy tree has the strength to compartmentalize and wall-off decay. Once a tree is compartmentalized, discoloration and decay will spread no further unless one of the barriers is broken. Storm-damaged branches should be properly pruned to expedite the healing process.

In the past, the best way to treat tree cavities was thought to just simply fill it with cement to block up the wound in the tree.  However, tree professionals know today that using cement does not allow for the tree to bend, grow, or flex in any way and therefore, it leaves the tree more vulnerable to any storm damage.  In addition, the cement will not bond with wood, which creates a gap between the tree and cement and allows for water to collect in the gap.  This dark and moist environment allows fungi to proliferate or grow rapidly. 

Fallen Tree

Fallen hollowed out tree due to a neglected cavity.


In most cases, it’s best to do nothing. A tree will seal over a small cavity eventually, and the tree’s new wood is stronger than anything put into the hole. Large cavities may never close, but as long as the tree does not sustain further damage, a basal cavity may not be a problem. If a cavity is determined to be weak and decaying, the professionals at Affordable Arbor Care can treat the cavity to create drainage if it is holding water and seal it with a water proof latex spray to protect it from further damage. 

Lightening strike on Live Oak


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