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Cracks can cause hazards in trees.

Tree failure is a major cause of property damage, especially during high winds. If the wind is strong enough, even healthy trees can be uprooted or broken, but it might not take a storm or high winds to cause a cracked or rotted tree to fail under its own weight.

"Homeowners worried about trees falling and damaging property should call a qualified arborist for an onsite inspection," advises Tchukki Andersen, staff arborist with the Tree Care Industry Association, Londonderry, N.H. Andersen notes that trees are genetically designed to withstand storms, but all trees can fail--and defective trees fail sooner than healthy ones.

Cracks in the trunk can be one of the major indicators of an unstable tree. Most are caused by improper closure of wounds or by the splitting of weak branch unions. They can be found in branches, stems, or roots and vary in type and severity.

For instance, horizontal cracks run across the grain of the wood and develop just before the tree fails, making them very difficult to detect. Vertical 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 halves. As the tree bends and sways in the wind, one half of the stem slides over the other, elongating the crack. Eventually, the enlarging crack causes the two halves of the stem to shear apart.

Ribbed cracks, meanwhile, are created as the tree attempts to seal over a wound. Margins of the crack meet and mesh, but are reopened due to tree movement or extremely cold temperatures. Thicker annual rings are created in order to stabilize the developing crack at the wound. This forms the ribbed appearance over a period of many years.

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Title Annotation:Landscaping
Publication:USA Today (Magazine)
Article Type:Brief article
Geographic Code:1USA
Date:Apr 1, 2017
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