Trees provide significant benefits to our homes and cities, but
when trees fall and injure people or damage property, they are
liabilities. Taking care of tree hazards makes your property
safer and prolongs the life of the tree.
Trees are an important part of our world. They offer a wide
range of benefits to the environment and provide tremendous
However, trees may be dangerous. Trees or parts of trees may
fall and cause injury to people or damage to property. We call
trees in such situations hazardous, to signify the risk involved
with their presence. While every tree has the potential to fall,
only a small number actually hit something or someone.
It is an owner’s responsibility to provide for the safety of
trees on his or her property. This brochure provides some tips
for identifying the common defects associated with tree hazards.
However, evaluating the seriousness of these defects is best
done by a professional arborist. Regular tree care will help
identify hazardous trees and the risk they present. Once the
hazard is recognized, steps may be taken to reduce the
likelihood of the tree falling and injuring someone.
Hazardous Trees and Utility Lines
Trees that fall into utility lines have additional serious
consequences. Not only can they injure people or property near
the line, but hitting a line may cause power outages, surges,
fires, and other damage. Downed lines still conducting
electricity are especially dangerous. A tree with a potential to
fall into a utility line is a very serious situation.
Tree Hazard Checklist
Consider these questions:
- Are there large dead branches in the tree?
- Are there detached branches hanging in the tree?
- Does the tree have cavities or rotten wood along the trunk or in
- Are mushrooms present at the base of the tree?
- Are there cracks or splits in the trunk or where branches are
- Have any branches fallen from the tree?
- Have adjacent trees fallen over or died?
- Has the trunk developed a strong lean?
- Do many of the major branches arise from one point on the trunk?
- Have the roots been broken off, injured, or damaged by lowering
the soil level, installing pavement, repairing footpaths, or
- Has the site recently been changed by construction, raising the
soil level, or installing lawns?
- Have the leaves prematurely developed an unusual color or size?
- Have trees in adjacent wooded areas been removed?
- Has the tree been topped or otherwise heavily pruned?
Defects in Urban Trees
The following are defects or signs of possible defects in urban
trees (see figure):
- regrowth from topping, line clearance, or other pruning
- electrical line adjacent to tree
- broken or partially attached branch
- open cavity in trunk or branch
- dead or dying branches
- branches arising from a single point on the trunk
- decay and rot present in old wounds
- recent change in grade or soil level, or other construction
Defects in Rural Trees
The following are defects or signs of possible defects in rural
trees (see figure):
- recent site construction, grading and tree removal, clearing of
forests for development
- previous tree failures in the local area
- tree leaning near a target
- forked trunk; branches and stems equal in size
- wet areas with shallow soil
Managing Tree Hazards
As expert tree surgeons can help you manage the trees on your property and
can provide treatments that may help make your tree safer,
reducing the risk associated with hazardous trees. We may suggest one or more of
- Remove the target. While a home or a nearby power line cannot be
moved, it is possible to move picnic tables, cars, landscape
features, or other possible targets to prevent them from being
hit by a falling tree.
- Prune the tree. Remove the defective branches of the tree.
Because inappropriate pruning may weaken a tree, pruning work is
best done by a qualified tree surgeon
- Cable and brace the tree. Provide physical support for weak
branches and stems to increase their strength and stability.
- Provide routine care. Mature trees need routine care in the form
of water, fertilizer (in some cases), mulch, and pruning as
dictated by the season and their structure.
- Remove the tree. Some hazardous trees are best removed. If
possible, plant a new tree in an appropriate place as a
Recognizing and reducing tree hazards not only increases the
safety of your property and that of your neighbors but also
improve the tree’s health and may increase its longevity!
Ensuring Quality Care for Your Tree
Trees are assets to your home and community and deserve the best
possible care. If you answered “yes” to any of the questions in
the tree hazard checklist or see any of the defects contained in
the illustrations, you should have your tree professionally examined by us.