Tree Trunk Cracks – What Causes Them?

To observe cracks in the trunk of your tree is a bit distressing, and understandably so. Tree cracks, whether your favorite maple in the front yard or the ash in your garden, are a sign of potential illness. While most prevalent among young, thin-barked trees such as ash, maple, and apple, all trees are susceptible to trunk cracks, given the right conditions. The reason behind the cracks, their purpose, and prevention is vital for the health and safety of your tree. In this tutorial, we will teach you everything about crack types and how to prevent cracks.

Understanding Different Tree Trunk Crack Types

Vertical Cracks (Frost Cracks)

Among the most common cracks, vertical cracks (or frost cracks) are cracks that cut along the grain of the tree. They are typically triggered by variations in temperature. For example, on a sunny winter day, the bark will expand slightly. The bark swells in response to rapid temperature changes and may chip under the sudden change.

Impact:  As frost cracks exacerbate and become more significant, they can eventually damage the structure of the tree, especially when the tree experiences high winds.

Horizontal Cracks

Unlike vertical cracks, horizontal cracks occur along the grain of the wood. They tend to indicate stress or fungal decay inside the tree. Rapid growth, excessive water stress, or pathogens in the tree base are possible causes.

Impact: Horizontal cracks undermine the tree’s integrity and are a grave threat to the overall health and safety of the tree.

Ribbed Cracks

Split cracks form over time as trees try to recover from damage or stress. Such cracks will often appear ridged and open or closed, depending on the environmental conditions.

Impact: Ribbed cracks suggest residual stress and increased weakness, potentially resulting in more structural instability.

What Are The Reasons for Tree Trunk Cracks?

• Sunburn and Sunscald: In the sunshine, the day is pleasant, but in young or debarked trees, exposing the bark to too much sunlight causes it to become weak. This condition, sunscald, typically develops when harsh sunlight followed by fast cooling eats away at the bark and surrounding tissues.
• Frost Cracks: Colder environments pose challenges. If water in the bark freezes and expands, frost cracks can form – especially in trees such as maple and apple, which are particularly vulnerable to these extremes.
• Sudden Irrigation Changes: The swings between drought and intensive irrigation wear on the bark, triggering rapid growth that may not keep up with the outer coat.
• Late-Season Fertilization: Fertilizer applied late in the season can stimulate a final surge of growth at the moment the tree should be entering dormancy. This late growth is weaker and more susceptible to winter damage, allowing for the possibility of cracks.

Tree Species Susceptible to Cracks

• Highly Susceptible: Maple, ash
• Moderately Susceptible: Apple, sycamore

If you have these trees in your yard, they require special attention.

How to Stop Tree Trunk Cracks?

• Trees Young With Scary Bark: Protect tender or damaged trees with a protective wrap during the winter months. Covering the trunk with white paper or special tree wraps will help prevent frost cracks and sunscald.
• Ensure Stable Environmental Conditions: Do not dramatically alter watering schedules. Regular watering throughout the year helps to prevent stress-induced cracking, and regular fertilization ensures that the tree does not experience late-season growth spurts.
• Provide Proper Shade and Pruning: Over-pruning can expose trees to too much light, which may lead to sunscald and frost cracks. Keep them shaded in a balanced way by pruning appropriately, and consider shrubs or other plants for extra protection around vulnerable trees.
• Call an Expert: Cracks do not come in any one size. Some may suggest structural imbalances, fungus, or even severe health issues that need expert intervention. Arborists are equipped with special tools and training to inspect trees and make necessary repairs. And routine tree care checks can detect and solve small issues before they grow into bigger issues. When you detect large, deep cracks or soft, decaying areas near the crack location, hire a professional to keep rot or tree failure from progressing.

Keep Your Trees Standing Strong

Broken tree trunks are not always signs of impending doom, but they are a loud warning. Everything from weather change to mismanaged watering, knowing what causes cracks can keep your trees safe and healthy while maintaining a dense, pleasing presence in your landscape.

With a few simple preventative steps such as trunk wrapping, frequent watering, and trimming properly, stress can be reduced and the tree is healthy. But if cracks appear to be serious or troubling, then you can only trust the professional services of a certified arborist to keep your tree and surrounding environment safe. 

Do you have concerns about the condition of your tree? Call Kanata Tree Service Masters to keep your trees flourishing all year round!