From holes in the trunk to falling branches, here's how to spot a problem before serious damage can be done.
Credit: Getty / Pamela Webb / EyeEm

Trees provide cool shade, fruit, branches that rustle in the wind, homes for our kids' playhouses, and so much more—plus, they hold sentimental value (you'll never forget the massive oak that hovered over your childhood house's porch). But when your trees are in trouble, they quickly turn dangerous; when they fall, they often leave catastrophic damage in their wake. Stay ahead of the game by paying attention to the following six signs that indicate when it's time to call an arborist to asses your tree's health—and ultimately explore your options for removal.

A Hole in the Trunk

A branch falls for any number of reasons, from damage from a storm to improper pruning techniques. No matter the cause, a downed branch often creates a cavity in the tree—and while that cavity doesn't necessarily spell disaster (a healthy tree can build more wood and seal them off), a tree that's already under stress, or otherwise declining, can have trouble bouncing back. Opportunistic bacteria then fills the cavity, causing decay and compromising the tree's health. If you see a big cavity, one that is expanding with rot, it's time to call an expert.

One thing to note: While you may remember once seeing cavities filled with concrete or foam, both of these practices have fallen out of favor; they aren't beneficial to the tree. It's highly likely that you'll be sealing in the bad stuff, creating further opportunity for decay.


A canker refers to a part of the tree bark that might be missing, gashed, or deeply cracked and is most often caused by a mechanical injury or fungi or bacteria. While most plant pathogens can't directly attack bark, they'll quickly colonize an area that's wounded or exposed. Canker-born diseases also vary in seriousness. While some might not kill trees outright, they can be sites for pathogens that lead to eventual (but deadly) decay—something that becomes very problematic during high winds or heavy snow.

Falling Branches

A telltale clue that a tree isn't happy? Falling branches. This often occurs during the summer, when temperatures are at their highest. Arborists don't necessarily agree on the root cause—some say it can be triggered by high humidity within the tree, while others blame internal issues like bacteria. No matter the origin, when a branch comes crashing down, it's time to pay attention—as it might happen again and become a huge safety concern.

Leaning Trunk

While a tree that is naturally tilted (the result of how it's grown into the earth) poses less of a risk, a tree that's leaning more than 15 degrees, due to wind or root damage, usually needs to come out.

Losing Leaves from the Outside In

We're not talking about deciduous leaf drop here. Instead, look for a tree that loses leaves from inside the canopy first. This pattern of loss indicates that something has gone wrong in the root zone—and if the roots are in trouble, a tree is at risk for falling.

Rotten Roots

In that vein, root rot can spell all kinds of trouble for a tree's structural integrity. To inspect the state of your tree's roots, get down low, and look for mushrooms growing around the base of the trunk.


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