Dangerous Trees

By Kristen Castillo

August 3, 2018 5 min read

Trees provide so many benefits -- from clean air to shade and more -- but they can also be dangerous in stormy weather. Wild winds, rains, tornadoes and even heavy snow can put deadly strain on trees, potentially snapping limbs or even causing trees to topple over.

"Wind is not the only weather condition that can cause a tree to fail," says Alex Julius, education manager for the International Society of Arboriculture, a nonprofit that promotes the professional practice of arboriculture and fosters global awareness of the benefits of trees. "Areas that have flooded can leave trees waterlogged, and they could tip over when lacking the structure of the soil underneath."

For example, high winds and floodwaters from hurricanes Katrina and Rita in 2005 and Harvey in 2017 caused lots of tree damage. Now forestry experts are calling some of those trees badly damaged by Hurricane Harvey "zombie trees" because they're dying. Those dying trees pose a falling hazard. Just this summer, three people were killed by falling trees.

*Tree Risks

ISA recommends that homeowners find a qualified local tree risk assessor through the nonprofit's http://www.treesaregood.org website to determine whether their trees are at risk of falling or hurting people or property.

"We try not to use the word 'dangerous' to describe trees," says Julius. "Trees can be high-risk, depending on if there is a defect or condition that might fail." But "usually, trees are not a risk to public health, and the actual likelihood of a tree failing and landing on a target is low."

Here are some signs your tree may be at risk:

--It's adjacent to an electrical line.

--There's been recent site construction, grading or a change in soil level or grade.

--The tree has developed a strong lean in a particular direction.

--There is visible decay or rot.

--You see dead, dying, broken or partially attached branches.

--The trunk is cracked or split.

--The base is in a wet area with shallow soil.

--It has a forked trunk where the branches and stems are the same size.

--There have been other tree failures in the local area.

Examine your trees at least once a year for damage, decay and other concerns.


Mitigating a tree problem could include pruning or cabling it or restricting traffic near the tree.

Moderate pruning is generally OK, but cutting the top of a tree, known as topping, is a bad move because it prevents the tree from growing.

Though homeowners often want to tackle tree trimming, experts say it's best to call a certified arborist to do the job. ISA says improper pruning can weaken a tree.

The Occupational Safety and Health Administration says it's never a good idea to trim trees during dangerous weather conditions.

OSHA warns both amateur and professional tree trimmers to stay alert while cutting and removing trees.

If a broken tree is under pressure, OSHA recommends making small cuts to release the pressure. The agency advises inspecting the limbs for strength and stability before you climb a tree. Be sure to determine the direction the tree would fall and have a safety plan. Trimmers should never turn their back on a falling tree.

*Safety First

Always wear protective gear, including gloves, safety glasses and a hard hat.

Take extra caution when trimming trees near power lines. OSHA advises contacting your utility company about de-energizing and grounding power lines. It says all trimming or removal work within 10 feet of a power line must be done by experienced and trained line-clearance tree trimmers. An additional tree trimmer is required within normal voice communication range.

OSHA reminds tree trimmers to use extreme caution with equipment, including ladders, while dealing with downed trees and power lines.

*Go Green

Not all trees can be saved from damage or rot. If you do remove a tree, consider planting a replacement nearby in a safe area. Monitor that new tree's health regularly.

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