How to Tell If a Tree Has Root Rot and Is a Safety Hazard

Root rot is a decay of the roots and lower trunk that weakens the tree's grip on the soil. A tree with root rot can fall without warning because the roots can no longer anchor it.

Roots do two jobs: they take up water and minerals, and they hold the tree upright. When fungi break down the root tissue, the wood becomes soft and crumbly. The tree may still look green because the canopy can be fed by remaining roots, but the base is failing. The danger is that the tree loses its anchor. A windstorm or even a saturated soil after heavy rain can tip it over. The fall can happen at the base, with the root plate lifting out of the ground, or the trunk can snap where the decay is worst.

Root rot is not always visible from the surface. You often have to look for clues at the base of the tree, in the soil, and in how the tree is growing.

• Look for mushrooms or conks at the base or on exposed roots.
• Check for soft, spongy, or crumbly wood near the ground.
• Look for a new lean, soil cracks, or a raised root plate.
• Watch for dieback in the canopy that starts at the top and works down.

You can often spot root rot by looking for mushrooms, conks, or a hollow at the base of the tree. These are the most reliable above-ground signs.

Fungal fruiting bodies are the clearest clue. Mushrooms growing in a cluster at the base of the trunk or on roots mean decay is active. Conks, which are hard, shelf-like brackets, also indicate internal decay. Not every mushroom means the tree is a hazard, but any conk on a root or buttress is a reason to look closer.

Other visible signs include:

• Soft or spongy wood when you press a screwdriver into the base. Healthy wood resists; decayed wood gives way.
• A hollow or cavity at the base of the trunk, especially if it is wider than a few inches.
• Bark that is loose, sunken, or missing near the soil line.
• Adventitious shoots, which are small branches growing from the lower trunk or root flare. Trees sometimes send these out when the root system is stressed.
• A root flare that is not visible. On many trees the base should widen where it meets the soil. If the trunk goes straight into the ground like a telephone pole, soil may have been added over the roots, which can smother them and lead to rot.

These signs do not prove the tree is a hazard on their own. They tell you to investigate further.

You can check for root rot without digging by probing the base with a screwdriver, looking for a lean, and checking the soil for cracks or a raised root plate. A tree that fails the probe test or shows movement at the base needs a closer look.

Start with the screwdriver test. Push a long screwdriver into the base of the tree at several points around the trunk, about six inches above the soil line. Healthy wood will resist. If the screwdriver sinks in easily, the wood is decayed. Do this gently; you are not trying to stab the tree, just feel the resistance.

Next, look for a lean. A tree that has always leaned is not necessarily a problem, but a new lean is. Check the soil around the base for cracks or a gap between the root plate and the ground. If the soil is pushed up on one side, the tree may be tipping.

You can also check for a hollow by tapping the trunk with a mallet. A dull thud instead of a sharp crack can mean the inside is hollow. This is not foolproof, but it is a quick check.

Finally, look at the canopy. Dieback that starts at the top and works down, or a thinning crown, can point to root problems. A tree with a full canopy can still have root rot, so do not rely on the leaves alone.

A tree with root rot is an immediate safety hazard if it is leaning, if the root plate is lifting, or if more than half the trunk circumference is decayed at the base. Those conditions mean the tree can fall without much warning.

The risk goes up with these factors:

• The tree is within falling distance of a house, driveway, power line, or sidewalk.
• The tree has a new lean of more than a few degrees.
• You can see a gap between the root plate and the soil, or the soil is cracked around the base.
• The decay is on the side of the tree that faces the target. A tree with rot on the side away from the house is less likely to fall toward the house, but it can still fall.
• The tree is a species that is prone to root rot, such as oak, maple, or pine, especially in wet or compacted soil.
• There has been recent construction, grading, or soil compaction near the tree.

If the tree is leaning and you see soil cracks, do not wait. Keep people and pets away from the area and call a tree removal service to assess it.

If you suspect root rot, keep people and vehicles out of the fall zone and call a tree removal service to assess the tree. The fall zone is at least as wide as the tree is tall.

Here is a safe sequence:

1. Mark the fall zone. Measure the height of the tree by comparing it to a known object, or estimate by eye. Keep everyone out of a circle that wide.
2. Do not try to cut the tree yourself. A tree with root rot can barber-chair or fall in an unexpected direction. The wood at the base may be too weak to hold a hinge.
3. Take photos of the base, the mushrooms, the lean, and the soil cracks. These help when you call.
4. Call a tree removal service. In Springfield, MO, you can reach us at [phone number]. We will look at the tree and tell you what we see.
5. If the tree is in a public right-of-way or near power lines, call the utility first. They may need to disconnect service before any work starts.

When we assess a tree with suspected root rot, we look at the base, the lean, the soil, and the canopy. We may use a probe or a mallet to check for hollows. If the tree is a hazard, we explain what removal involves and what it will cost. The cost depends on the size of the tree, how close it is to structures, and whether the wood can be dropped in one piece or has to be rigged down in sections. We do not give a price over the phone because the number depends on what we find on site.

A tree with root rot can sometimes be saved if the decay is caught early and the tree is not a hazard, but once the root plate is failing or the trunk is hollow, removal is the safer choice.

Treatment depends on the cause. If the rot is from a fungal infection, there is no cure that reverses decayed wood. You can improve growing conditions by aerating compacted soil, reducing watering, and removing mulch that is piled against the trunk. These steps may slow the spread. A certified arborist can tell you if the tree has enough healthy root tissue to survive.

If the tree is a hazard, removal is the only way to remove the risk. The decision comes down to this: if the tree can hit something you care about, and the base is failing, it is time to remove it. If it is in an open field with nothing in its path, you may choose to monitor it. But monitoring a tree with a lifting root plate is a gamble. The tree does not heal the way a broken bone does; it walls off decay, and the wall may not hold.

Walk outside and look at the base of the tree. If you see mushrooms, a new lean, soft wood, or soil cracks, call us at [phone number]. We will come out, assess the tree, and tell you what needs to happen. If it is a hazard, we will remove it safely. If it can wait, we will tell you that too. The important thing is to look now, before the next storm.