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Is My Tree Dangerous?

Vista arborists cleaning up branches after dangerous tree pruning in front of a 3-car garage on a sunny day

One of the most common questions we get from clients is: Is my tree dangerous? It’s followed by its close companion: Is my neighbour’s tree dangerous? Fortunately, many of the scenarios where people think a tree is dangerous aren’t actually a risk.

Conversely, some of the cases where a tree is actually dangerous aren’t easy to spot for the average homeowner! We’ll take you through when you should worry about a tree and when you shouldn’t, plus how to know when to call a professional.

How to Assess a Tree

Luckily, you probably already have some of the skills needed to get an early idea of whether you have a dangerous tree. Many of the signs of an unhealthy tree are easy to spot. Broken branches, damage, discoloured leaves or few or no leaves at a time of year that the tree should have them are just a few of the early warning signs of a tree in less than perfect health.

Which Conditions Are Actually Dangerous

A frequent concern is that a tree is “too tall.” Height in itself isn’t a concern if a tree is healthy and in good shape. Trust that your tree knows its growing limitations!

A tall tree located near a house is also not a reason to worry, unless the tree really is planted too close to the house. The taller a tree grows, the further from a building it needs to be planted. However, if the tree is within a safe distance from the building for its height and is in good health, you don’t need to worry about it.

When to Worry About a Dangerous Tree

Dead Branches

Dead branches are both a sign of poor health and a risk on their own. They are at high risk of falling at any time, especially during adverse weather conditions. If a big storm hits, these weakened limbs will be the first to fall.

Not only are dead branches dangerous on their own, they are often a sign a tree is in rough shape. Disease, infestation, and nutrient deficiency can all cause branches to die off. The dead branches may be the first visible indication that year tree is dying and needs to be removed for safety. Get an arborist to assess your tree’s condition and whether the damage is limited to a small area or all over.

Broken Branches

Broken branches are also a big risk for falling. A storm or strong winds can easily cause these branches to break off. They could then land on your home, car, garage, or a person outdoors.

Branch Damage

A tree can usually recover from more minor branch damage, but when more than 25% of branches are damaged, this can be a problem. It is difficult for a tree to heal from larger-scale damage.

Trunk Damage

Tree with trunk damage

Hollow spots in a tree’s trunk, cuts, wounds, and other damage to the trunk is often fatal for a tree. Deep cracks in the bark expose the interior of the tree, leaving it vulnerable to pests, infection and damage.

Sometimes hollow cavities in a tree’s trunk can be managed. Trunk damage from a storm can also affect the whole tree’s health, since all nutrients need to flow through the trunk.

Have an arborist assess whether your trunk damage is fixable.

Two Trunks

When trees have two trunks and they are growing in a V shape, this can indicate potential weakness in the tree. An arborist may be able to help stabilize the tree by cabling or bracing.

Root Rot

Mushrooms along your tree’s roots can be an indicator of a deep fungal infection. When a tree’s roots start to rot, the tree’s stability is affected. When you see mushrooms here, have a professional come and assess whether the infection can be treated.

Shallow Roots

Many shallow, visible roots can mean your tree isn’t getting enough water and nutrients. Exposed roots are also vulnerable to both pests and physical damage from everything from lawnmowers to human foot traffic.  An arborist can help assess the tree and root condition and add or turn soil as needed.

Roots damaged by construction, paving, or anything else should also be assessed.

Unbalanced Crown

A tree with more branches growing on one side or the other or an unbalanced shape overall can indicate a problem. This may mean the tree is unstable. However, these issues are often easy for an arborist to fix with pruning or cabling.

Leaning Trees

Some trees end up growing in a leaning direction. Depending on the size and location, a lean isn’t necessarily a problem if a tree has grown that way all along. However, if a tree has developed a recent lean, this may indicate a structural problem. It’s a good idea to have a professional assess it.


Decay can be a major sign of a dangerous tree. Mushrooms, fungus, and crumbling bark can all mean that the interior of your tree is decaying. Sometimes this can be hard to spot because a tree continues to grow healthy bark and wood that covers the decay. It’s crucial to have a professional evaluate your tree in this case.

Dangerous Trees Around Power Lines

If a tree is close to power lines, the bar is lower for whether it’s dangerous. Breakage over electrical lines can cause a major risk to property and human life. Never climb into a tree near electrical wires to check its condition yourself. Always have a certified arborist assess any issues involving power lines.

For any urgent safety concerns with hydro lines, Hydro One and Toronto Hydro will send one of their arborists to service trees.

Who Do I Contact About a Dangerous Tree?

If you’re worried that your tree is dangerous, contact an arborist to have them assess it. We’ll see whether the tree actually poses a risk. Many times, a lower-intervention method like pest treatment, pruning or cabling, can resolve an issue with a tree’s health and safety.

When a tree really is a hazard, we know how to take down a dangerous tree safely. We’ll also go through your municipality’s permit process for you to have the tree removed.

It’s important to have any concerns and risks with your tree dealt with promptly. Small treatable issues can become big problems over time, leading to removing dangerous trees when a pruning job may have solved the problem earlier.

When you have questions about your tree’s health and safety, contact Vista Tree for a consultation by certified arborists.

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