6 Signs of Potentially Hazardous Trees

My Garden Life
February 10, 2021
Table of Contents
Trees provide a diverse assortment of benefits to the planet, but they can also represent a safety hazard. Falling branches and failing trees can cause property damage, injuries or even deaths. Learning to spot the signs of potentially hazardous trees early can spare you from bigger problems down the road.
The best way to protect yourself and your family is by securing the services of an experienced arborist. An arborist can determine if any of the trees on your property are at an increased risk of failure. Remove trees that are hazardous at once – the stakes are simply too high to procrastinate.
While it takes the experienced and educated eye of an arborist to spot some potentially hazardous signs, others are obvious. Observe your trees for any of the following signs.

1. Large Cracks

large crack in a tree trunk
Cracks in a tree’s wood – whether situated vertically or horizontally – represent a serious safety hazard. But cracks may not show any sort of systemic problem. Cracks often occur when an unnatural stress is placed upon the tree, such as hanging a swing from a large branch. Accordingly, it is not always necessary to remove trees with cracks, unless the crack occurs in the trunk or on one of the primary branches of the tree.

2. Large Cavities can Result in a Hazardous Tree

A large cavity in a tree trunk is a sign of a potentially hazardous tree.
Cavities often begin from relatively minor phenomenon, such as a dropped limb. The cavity grows larger when destructive fungi digest the wood. This can compromise the integrity of the tree and predispose it to failure. Cracks with edges that “roll” inward are almost always associated with significant decay and need removal or structural pruning.

3. Mushrooms Growing from the Trunk, Primary Branches or Roots

Mushrooms growing on tree trunk
If mushrooms are emerging from a tree, the fungus’ hyphae are likely penetrating the wood and causing decay. This type of decay takes some time to cause damage to the tree’s wood. But the presence of mushrooms often signals accelerated decay. Contact a certified arborist to examine the tree and assess the risk.

4. Co-dominant Stems

tree with co-dominant, or twin trunks
Arborists use the term co-dominant stem to refer to trees with “twin” trunks. Unlike proper branches, co-dominant stems do not feature strong attachment points. If exposed to strong winds, they may split at the junction point. A split like this will likely kill the tree and send thousands of pounds of wood crashing to the ground. Removal is occasionally necessary for trees with co-dominant stems, but using supportive fixtures can often make these trees safe.

5. Girdling Roots

girdled tree roots
Girdling roots wrap around the base of the tree. They choke off the transport of sugars through something called the phloem, which is right under the tree’s bark. Girdling roots are often caused by improper planting. If they are caught early enough, the roots can be pruned, thereby giving the tree a chance to recover. In some cases, these trees can be saved through aggressive root pruning, but others are often too damaged.

6. Hazardous Trees Often have a History of Limb Drop

fallen tree limb in a lawn
Trees that have dropped limbs in the past are more likely to drop limbs in the future. This is obviously true of trees that are coping with pests or disease, but it is also true of trees that otherwise appear healthy. Accordingly, it is wise to have an arborist inspect any tree that exhibits limb drop.
Be sure to observe your trees regularly so you can catch these problems early. Contact an ISA-certified arborist if you note any of the above signs on your trees. Keep the area clear until the arborist inspects the tree. By acting quickly, you have a better chance of saving any trees that can be rendered safe. Plus, you ensure your family stays out of harm’s way.
snowy home landscape in winter
Now that you know the potential signs of trouble for trees, check out our tips for preventing damage to trees during winter.


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