Forestry & Wildlife
AUBURN UNIVERSITY, Ala. —Trees are a coveted asset in the yard—that is until the trees present a hazard. Recognizing these potential tree hazards in the early stages could save a tree, as well as your wallet.
Identifying Potential Tree Hazards
One of the first major signs of a hazard is a tree with a recent lean. Trees can lean naturally; they might be growing towards the light or away from other trees and structures.
Beau Brodbeck, Alabama Extension community forestry and arboriculture specialist, said, “You should be very worried about a tree if a storm has come through in recent weeks or months and the tree has a new lean.”
On the opposite side of the lean, mounding will begin to appear where the roots are pulling up out of the ground. On the same side of the lean, the homeowner may see slight indentation where the roots are being pushed further into the ground. This will indicate a hazardous lean which can be very dangerous, especially if it’s recent.
Trees with cracks indicate a potential hazard as well. A past storm or tornado could have twisted the tree, causing a spiraling crack going up the tree.
“Use a coat hanger or something to probe inside the crack to discover how deep it goes,” Brodbeck said. “If it is deeper than bark level, it is a hazard.”
Sometimes when there is a forked tree, cracks may appear at the union of the fork. At that point, the tree is pulling apart under its own weight.
“Anytime you see a crack, whether it’s between two branches on a forked tree or on the trunk, immediately seek further evaluation,” he said.
Cut roots will present a hazard and require further evaluation.
“Any roots within 5 to 10 feet of the tree that are about 2 inches or larger in diameter are cut, the tree might be a hazard,” he said.
Cuts typically occur on trees next to new construction like a sidewalk, building or a new home.
Another visible indicator of hazardous trees is broken or hanging limbs. Big dead snags will eventually come out and present a hazard to people and property under the tree.
While many of these indicators of a potential hazard are easily identifiable, others are not. Any evidence of rot or decay in the tree may not always be as noticeable from the outside. “Your tree can be full of rot and it may not always be visible,” said Brodbeck.
Signs of Decay
The not-so-subtle signs of decay are the fruiting bodies of fungi like mushrooms sprouting from the roots, base or trunk of a tree. Some of these fruiting bodies, referred to as conchs, don’t look like traditional mushrooms. Instead, they might look like half of a flying saucer that can be tough and woody.
Like anything that fruits on the tree, the mushrooms may be there for a while then decompose and fall off. This makes it harder to identify rot in the tree. It is sometimes helpful to look for old mushrooms and conks that have fallen away from the tree.
Other signs of rot include any type of oozing from the trunk or large branches in the tree. If the tree has a small opening with what appears to be a dark stain where liquid has leaked out of the tree, that oozing will often indicate some type of rot inside the tree. The oozing liquid will often have a foul, yeasty smell.
Openings or Cavities
Any large openings, or cavities, in the tree indicate decay as well. If limbs have broken off that leave a large wound, this will require further evaluation of the tree. Anytime open cavities have nesting critters in them, like squirrels, it is large and extensive enough to raise concerns.
Dead or missing bark on the side of the tree could also indicate rot. If a lot of bark is falling off, anything over one-fourth or one-third of the tree diameter will be a potential major problem.
Lastly, abnormal swelling in the trunk of the tree is a subtle sign of potential decay. Trees generally taper from thick at their base and slimmer further up. If abnormal swelling counter to the taper is visible, that is an indicator that there is some type of defect inside the tree.
“Just because a tree has decay, it does not mean it is unsafe and needs to be removed,” Brodbeck said. “It simply means you need to have someone take a closer look.”
Some of these decay pathogens are very aggressive and will kill a tree within a year or so. Some of them can be in the tree for decades and will cause slowly deterioration, but it is not something that requires immediate action.
Targets of Hazard
For a tree to be hazardous, there should be a target. Whether the target is a home, vehicle or residents—make sure to identify these targets before evaluating the tree hazards.
The solution to a potential tree hazard is not always to immediately cut it down. Often simple pruning can benefit the tree. Therefore, it is important to contact a specialist.
Once potential tree hazards are identified, look into getting a second opinion. Regional Alabama Extension agents can help to evaluate hazardous trees and give educated guidance on the proper next steps.
Also, the International Society of Arboriculture has a tree risk assessment qualification. Homeowners can also contact a certified arborist about further evaluation.