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

Example 4: Live Oak in Residential Yard

Pruning practices are more important than we tend to think. When done right, pruning leaves the tree less prone to wind damage. Often, however, selectively removing limbs will make the tree more vulnerable to wind damage than before, especially if it produces an imbalance that stresses the trunk or specific limbs. The surgeon must remember that pruning performed today will result in long-term changes to the tree, some of which are difficult to visualize without benefit of extensive experience.

This example is one of the exceptions to the rule that diseased trees are most susceptible to wind damage. This Live Oak (Quercus virginiana) lost a large limb, but examination of the limb did not indicate that disease was a factor. Instead, pruning of the tree during construction of the home had left the tree poorly balanced, with a large, relatively heavy limb projecting from a relatively spindly trunk. The limb that was severed by the wind appeared to be one of the healthiest limbs on the tree. As a result, it was covered with a profusion of secondary limbs. These, with their complements of leaves, caused the main limb to bear the full brunt of the wind.

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