7 Signs a Tree Is Dangerous and Should Come Down

I’ve lived in Minnesota long enough to have a healthy respect for what a tree can do when it decides to come down. After a derecho ripped through our neighborhood a few years back, I watched a massive, healthy-looking oak split right in half and crush my neighbor’s shed. The tree had looked fine from the street—until it wasn’t. That’s why I’ve learned to spot the warning signs early. Whether it’s oak wilt, storm damage, or just old age, knowing the signs a tree is dangerous can save your roof, your car, and maybe even a trip to the ER. Here are the seven red flags I’ve seen—and the ones I ask every arborist about before I make the call.

1. Large Dead Branches or a Dead Crown

This is the most obvious sign, but it’s easy to overlook when you’re busy. If more than a quarter of the tree’s canopy is dead, that tree is struggling. Dead branches are brittle and can drop without warning, especially during a Minnesota thunderstorm.

What to look for:

• Bare branches in summer when other trees are full
• Peeling bark or no leaves on major limbs
• Mushrooms or fungus growing on the trunk or roots

A tree with a dead crown is often beyond saving. If you see this, call a state-registered tree-care provider from the Minnesota Tree Care Registry to assess it before the next windstorm.

2. Cracks or Splits in the Trunk

Vertical cracks in the bark might look cosmetic, but deep splits that go into the wood are a structural failure waiting to happen. I had a maple with a crack running from a frost crack all the way up to a branch union—it didn’t survive the next winter.

Pay attention to cracks that:

• Are wider than a few inches
• Run deep into the trunk (you can see the inner wood)
• Appear after a storm or freeze-thaw cycle

If a crack extends into a fork or branch attachment, that limb is at high risk of snapping. Don’t wait—get a professional opinion.

3. Leaning Trees (Especially After Storms)

A tree that suddenly leans is different from one that grew that way. If you notice a new lean after heavy rain or wind, the root system may have been compromised. That’s one of the most urgent signs a tree is dangerous because the entire tree could uproot.

Check for:

• Soil heaving at the base (a mound of dirt on one side)
• Exposed roots or cracks in the ground near the trunk
• A lean that’s getting worse over time

In Minnesota, heavy spring rains and freeze-thaw cycles can loosen soil around roots. If your tree leans more than 15 degrees, have a certified arborist look at it—ideally one who is also on the Tree Care Registry.

4. Damage from Pests or Disease

Emerald ash borer has killed millions of ash trees in our state, and oak wilt is a constant threat. A tree that’s infested or infected is structurally weaker and more likely to fall.

Signs of serious trouble:

• Woodpecker damage (lots of small holes in a pattern)
• D-shaped exit holes on bark (EAB sign)
• Sudden leaf drop or wilting in summer
• Fungal conks (bracket fungi) on the trunk

If you have an ash tree, don’t wait for it to die. A dead ash can drop limbs or fall within a year. For oaks, avoid pruning from April to July to prevent oak wilt spread—but if you see symptoms, call a pro who knows Minnesota’s timing.

5. Hollow or Decayed Trunk

A hollow tree isn’t always dangerous—it depends on how much sound wood is left. But if the hollow extends more than 30% of the trunk’s diameter, the tree is at risk of snapping in high winds.

How to check:

• Gently tap the trunk with a rubber mallet—a hollow sound means decay
• Look for cavities or holes where water can collect
• Check for soft, crumbly wood around the base

I’ve seen trees with huge cavities stand for years, but after a heavy snow or ice storm, they can fail catastrophically. If you’re unsure, a state-registered tree care provider can do a resistograph test to measure internal decay.

6. Weak Branch Unions (Included Bark)

Some trees grow with a V-shaped fork where two branches meet, and the bark gets trapped inside the union instead of growing together. This is called included bark, and it’s a weak point. These limbs are prone to splitting, especially under ice or wind load.

What to spot:

• A tight V-shaped crotch (not a U shape)
• Bark visible in the crack between branches
• Previous splits or cracks in that area

Maples, oaks, and birches are common culprits. If you have a tree with multiple V-shaped forks near the top, it’s worth having an arborist evaluate whether cabling or removal is the safer choice.

7. Root Damage or Girdling Roots

Roots are the foundation. If they’re damaged from construction, soil compaction, or growing in a circle around the trunk (girdling roots), the tree can’t anchor itself. I’ve seen trees blow over in a moderate wind because the roots were cut during a driveway project years earlier.

Warning signs:

• Visible roots that are circling the base
• Soil that’s been disturbed near the trunk
• Thinning canopy or smaller leaves
• Mushrooms growing at the base (indicates root rot)

If you’ve had any digging, grading, or paving within the tree’s drip line in the last 5–10 years, keep a close eye on it. Roots don’t heal fast, and the damage can show up years later.

Practical Takeaway: When to Call a Pro

If you see one or more of these signs a tree is dangerous, don’t guess—get a professional opinion. In Minnesota, look for a provider on the Tree Care Registry (that’s the state’s official list of registered tree-care businesses). You can also ask if they have an ISA Certified Arborist on staff—that’s a voluntary credential, but it shows they’ve passed an industry exam. Get at least two quotes for removal, and never let anyone climb or rig a tree near your house without proper insurance. Your home and family are worth the extra step.