Windstorm Damage of May 20, 2001
Disease Makes Trees More Vulnerable to High Winds

Example 2: Shumard Oak in Residential Back Yard

An examination of the roots revealed extensive fungal infection of the root heartwood. During windstorms, healthy roots provide a secure foundation for the tree and, in a healthy tree, this foundation will be so secure that the trunk will snap before the roots will give way. 

The bark on this tree had been severely damaged several years ago, at a point some 18 to 24 inches above the ground. Such injury often occurs during the clearing of a lot in preparation for home construction. The resulting wound has now become covered with bark, but the scar is not perfectly healed, and shows obvious signs of decay. These signs indicate that this wound had become infected by a fungus before new cambium could form over it. Such an infection would be expected to eventually cause the same heartwood rot seen in the tree on the previous page. This tree, however, had also become infected with a fungal rot in its roots, probably as the result of root damage while the lot was being cleared.

Above this scar, the trunk exhibits other partially healed wounds, including that shown in the photo at right. Deep fissures in the bark lead to decayed wood that is partially hidden by scar tissue and overlying bark.

Several round holes can also be seen in the bark overlaying the poorly healed wound. The rounded edges of these holes make them appear as though they had been made with a drill. These are the exit holes of adult wood boring beetles. Such beetles attack trees that have been stressed by mechanical injury or by diseases that prevent the tree from producing thick, healthy cambium and bark capable of resisting invasion by the borer's larvae.

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Not far from the oak shown on the previous page, another of the same species (again, a Shumard Oak, Quercus shumardii Buckl.) had fallen through a privacy fence from the back yard of a residence. In this case, the trunk was largely intact, but the roots nearest the trunk had snapped.

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