Tree Storm Damage

tree over houseEvaluating a Storm Damaged Tree

Hundreds of thousands of shade and street trees in Canada are storm damaged by wind, ice and lightning each year. Estimates of property value loss from tree storm damage can approach ten million dollars annually depending on how severe the weather is. There are ways to help you quickly understand and prevent costly storm damage to trees. There are no real "cures" here outside of proper planting, prevention measures and treatment.

Trees biologically adapt themselves to wind and ice if these destructive agents are part of an average annual growing season. Under normal weather conditions, trees sway in the wind and these movements strengthen the woody material developing the stem. This development is especially important on the prevailing wind side for hardwoods and opposite the wind side for conifers.

It is the abnormal weather condition and storm that damages and potentially kills trees. There is just no way to protect all trees from all types of storm damage. Trees simply are not adapted to survive worst-case storms.

Storm damage to trees usually comes in six ways - via blow-down, stem failure, crown twist, root failure, branch failure and lightning strike. Total tree collapse, crown twist and lightning strike are considered catastrophic tree events that need immediate and proper attention. Root failure, branch failure and stem failure are more subtle and can take years to kill the tree. There are ways to minimize the damage from each of these types of storm damage so follow the links.

Dealing With Total Tree Failure

Catastrophic tree failure and damage is not only dangerous but can cause significant property loss and will be expensive to remove. Here are some ways to deal with complete tree damage.


blowWith blow down, the tree is pushed over and damaged by high winds. There is very little you can do to storm proof or protect a tree from hurricanes, down-drafts or tornado winds. The wind force on a tree is often too great for the wood structure. Past tree abuse, poor maintenance and pest problems all predispose the tree to storm damage by weakening the supporting wood.

The "Cure": Keep trees healthy with timely watering and proper fertilization but don't over do. Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind firm and react more effectively to damage. Remove or treat pest problems.

Crown Twist:

Crowns are trees' leaves, twigs and branches. Trees are never perfectly symmetrical in all directions. But many trees, through past abuse and poor management, have lopsided crowns which can cause wind loading. More wind on one side of the crown than on another produces a twist on branches and the main stem. Stem twisting will magnify weaknesses around old injuries and the stem will split or branches collapse.

The "Cure": Eliminate lopsided crowns. Prune branches to produce a reasonably symmetrical crown. If more than 70 percent of the crown is on one side of a mature tree, consider tree removal and replacement. Guying and bracing branches are last-ditch efforts when a tree has to be saved in spite of itself.

Lightning Strike:

Lightning either moves in a narrow line down the branches, stems and roots or along the entire tree bole. Lightning directly destroys tree tissues by electrical disruption and heat all the way down the stem and there can be massive root damage. Damage caused by lightning leads to extensive water loss. Pests quickly attack a lightning weakened and damaged tree.

The "Cure": Install lightning protection systems on historic, rare, specimen or recreational area trees. Unfortunately, lightning strike is fairly common, most trees just can't be protected and have to be removed. Check your home owner's insurance policy to make sure you are covered for lightning strike removal.