Identifying Trunk Wounds and Signs of Decay
Trees may be resilient, but they’re not impervious to injury and decay.
Urban and suburban trees can be damaged by cars, lawn mowers, construction equipment or improper pruning. In more rural or forest settings, tree wounds most likely result from storms, fires, or animals. Here’s what you can expect if you discover that one of your trees is wounded or damaged:
Wounded TreesTree wounds occur when damage extends beyond the bark down to the next layer of wood. Trees don’t heal in the same way humans do. Instead, they evolved to take care of themselves through a process called compartmentalization, which means they isolate the damaged tissue to prevent any infestation or infection from spreading and eventually cover it with a callus.
If your tree is wounded, the damaged bark will need to be carefully removed while leaving the healthy bark that’s tight to the tree. Removing healthy tissue can make the tree vulnerable to further damage and decay. Dressing the wound isn’t necessary and can impede the compartmentalization process.
Trunk Holes or CavitiesTree wounds can sometimes create a hollow space in the trunk called a cavity. In most cases, a tree can isolate the cavity and remain healthy and structurally sound. Cavities can also benefit wildlife, as many animals make their homes in hollow parts of tree trunks. If you want to avoid a family of squirrels from moving in too close your back porch, the cavity can be filled in but be mindful of the material used. Some materials can cause more problems down the road so it is best to use soft, expanding foam that will not affect the tree too drastically as it grows.
Signs of Tree Decay Tree decay happens when bacteria, fungus, or pests enter the wood through a wound in the tree. Signs of decay include mushrooms growing in and around a wound, carpenter ants and branches that look weak or dying. Trees often react to decay with compartmentalization, just as they do with wounds.
How to Tell if your Wounded Tree is HazardousIf a wound is too large or if decay is widespread, a tree may become a hazard to your property and other people. Signs of a tree that could be dangerous include:
- Large dead or detached branches
- Cavities that aren’t healing
- Cracks or splits in the trunk or branches