Crack in a Tree Trunk: When Should You Be Concerned?

When you notice a crack in a tree trunk, it is natural to assume straight away that the tree is diseased or about to fall. However, not every split signals a serious issue. Some are only surface-level changes linked to growth or temperature fluctuations, whereas others may point to structural damage and require closer assessment.

Why can a tree trunk crack?

A trunk is continually exposed to changes in temperature, moisture and growth. Under certain circumstances, the expansion and contraction of its tissues can cause cracks in the bark, especially in older trees or those subjected to substantial environmental variation.

Injuries caused by poor pruning, machinery, animals or impacts may also break the bark open. In some instances, disease, pests or unfavourable growing conditions can contribute to cracks developing and worsening.

How can you tell whether the crack is superficial?

Start by inspecting the appearance of the crack, without trying to pull it apart, cut into it or remove sections of bark. A narrow, shallow split confined to the outer layer can mean something very different from a deep opening reaching the inner tissues.

It is also useful to check whether it remains unchanged or grows over time. Recording its development by taking photographs at intervals can reveal changes that would be difficult to identify from memory alone.

When can a crack in a tree trunk be a concern?

Deep, long or expanding splits deserve greater attention. The same applies where wood is exposed, cavities have formed, sections of the trunk are separating, or there are signs of decay around the opening.

Extra care is needed when the crack is linked to large branches, a leaning tree, exposed roots or signs of instability. In these situations, it is not advisable to try to fix the issue yourself using cuts or improvised fillers.

What should you not do when you find a crack?

A common response is to cover the opening with cement, filler or another material in an attempt to “seal” the trunk. This type of action can make the area harder to assess and does not necessarily address what caused the crack.

You should also avoid widening the opening with tools or removing healthy bark around it. Before taking any action, it is best to establish whether there is a genuine structural issue or simply a superficial alteration.