Holes in trees can be disconcerting. Many homeowners are unsure about what holes indicate for tree health, or what they should do when a hole appears. In this post, we address tree holes and talk about how a hole could be a sign of compromised structural integrity. Although holes are not always a sign that there is something wrong, it is best not to take chances.

Are tree holes hazardous? They can be if they cause the structural integrity of the tree to fail. If this happens, the whole tree or one of its main branches may plummet to the ground, which could lead to injury and/or property damage. On the other hand, many tree holes do not present a problem, and do not necessarily need to be filled. We warn against filling holes with concrete (which was frequently recommended in the past), because this can actually lead to more problems.

Let’s look at some common forms and causes of tree holes:

Splits and Cracks. Oftentimes a tree will form a split or crack in its trunk. Splits pose serious problems as they place stress on the structural integrity of the tree. Once a crack starts, it is likely to grow, as the tree buckles and sways in the wind. This is why it’s important to address them as early as possible. Cabling may be effective, but if the problem is too severe, you might need to remove a limb or even the entire tree. 

Mushrooms and Fungi. Fungi growing at a tree’s base suggest there may be a larger problem. Hollows can also be signs of fungal infection. Since some fungi are benign, and others are harmful, it is best to let an expert make the call and offer their advice.

Sapsucker and Woodpecker Holes. These destructive birds chip away at tree bark to access tree sap and resident insects. Woodpeckers and sapsuckers can do serious damage as they bore small holes in trees. While these birds don’t kill trees, their feeding can weaken them and leave them more susceptible to diseases and insect infestation.

Tree Hollows. These are often caused by fungi and can be a sign that there is decay inside the tree, which can ultimately lead to a loss of structural integrity. Squirrel holes can also be indicative of a problem.

Often a tree has holes but it is unclear if they are big enough to cause problems. Determining the structural integrity of a tree is as much an art as it is a science. Inspection and monitoring are key to ensuring the safety and long-term survival of the trees on your property.