Recognizing Tree Hazards: Cracks

Vertical or longitudinal cracks run with the wood grain along the length of the tree and may appear as shear or ribbed cracks (K. Bernard). Tree failure can cause significant property damage and personal injury, especially during stormy weather and high winds.  Even seemingly healthy looking trees can be uprooted or sustain broken limbs through wind, rain and snow.  Although storms can damage trees, a cracked or decayed tree can fail under its own weight, regardless of weather conditions.

Trees are genetically designed to withstand forces experienced in storms, but all trees will eventually fail – and defective trees fail sooner than healthy trees.

To a professional arborist, certain structural defects are indicators that a tree has an increased potential to fail.

Cracks in tree trunks or other limbs are one indicator of an unstable and potentially hazardous tree.  Cracks can be formed from a variety of factors such as poor closure of wounds or by the weak connections of branch unions.  These types of defects vary in severity and can be found in branches, stems or roots.

Horizontal or transverse cracks run across the grain of the wood and often develop just before tree failure, making them very difficult to detect.  Vertical or longitudinal cracks run with the wood grain along the length of the tree and may appear as shear or ribbed cracks.

Shear cracks can run completely through the stem and separate it into two distinct halves (arbtalk.co.uk).

Shear cracks can run completely through the stem and separate it into two distinct halves. As the tree bends and sways in the wind, one half of the stem slides over the other, elongating the crack. Eventually the crack enlarges causing the two halves of the stem to shear apart.

Cracks in any portion of a tree increase the risk of failure and when combined with other structural defects or site factors, create extremely hazardous situations.

If you have concerns about a hazard potential with any of your trees, contact your Certified Arborist at Barrett Tree Service East to schedule a time to discuss your concerns and management strategies to reduce potentially hazardous situations on your property.