blooming flowers climber in tree to prune beneficial mushrooms close up of lady bug on leaf japanese maple being pruned

tree history 1. Trenching in the critical root zone can cut anchoring roots and increase blow down risk

lean tree 2. One of the eight warning signs of a hazard tree is a tree that has begun to lean. Pay close attention to trees that have recently moved from a vertical position.

multiple trunks 3. Multiple trunks are susceptible to splitting.

weak branches 4. Weakly attached branches can eventually lead to branch failure.

How to Recognize and Prevent Tree Hazards

Eight Warning Signs Every Homeowner Should Know

Every year, our landscape changes as trees fall or break, causing property damage, power outages, and injury. While some tree failures are unpredictable, many can be prevented. By inspecting your trees for warning signs, many potential problems can be corrected before problems arise.

Trees should be inspected on a regular basis especially before and after storms. Larger trees have a greater hazard potential than smaller trees. A hazardous tree is a tree that has significant structural defects that are likely to lead to failure and possibly cause injury or damage.

If a tree is deemed hazardous, keep people, pets, and vehicles out of the area until the hazardous condition has been corrected.

Seek Professional help from one of our certified arborists to evaluate the potential hazards before the next storm hits. We can recommend the proper course of action to keep your trees safer and healthier. The following guidelines can help you recognize the warning signs of hazard trees.

For an interactive look at the signs of a hazard tree, watch Terrill Collier talk to the Garden Guy about specific characteristics of problem trees in this short video.

1. History.

Past tree care, construction and landscape activities can affect the health of your trees. Construction, trenches, and tree topping can all have adverse effects on your trees. If roots have been cut or disturbed, the tree may become unstable.

2. Lean.

Trees do not necessarily grow straight up. However, trees with a significant lean may indicate a problem. Look for cracked soil and exposed roots around the base of the tree which may indicate the tree has recently begun to lean.

3. Multiple Trunks.

Some trees develop multiple trunks. Trees with multiple trunks can break if the trunks are weakly attached. Trees with large trunks with splits or cracks have a high failure potential. Inspect these trees for cracks or splits where the trunks meet.

4. Weakly Attached Branches.

Inspect branches where they attach to the trunk. Tight V-shaped forks are more prone to break than open U-shaped unions. Trees with splits, cracks, and/or several branches arising from the same point on the trunk may also present problems.

5. Cavities & Decay Pockets.

Inspect the trunk or branches for peeling bark and hollow or decayed areas. Large decay pockets and decay where branches meet the trunk can indicate serious structural problems. Mushrooms or conks growing on or at the base of a tree are signs of decay-causing fungus.

6. Trunk & Branch Cracks.

Inspect the trunk and large branches for cracks. Deep, large cracks indicate structural weakness in the tree and need careful evaluation.

7. Hangers.

Hangers are broken branches still lodged in the tree. Whether partially attached or separated completely from the trunk, hangers are likely to fall unexpectedly and should be removed. Stubs left by broken branches should be removed to prevent spread of decay.

8. Deadwood.

Dead branches, or deadwood, will eventually fall. Branches over two inches in diameter can cause serious damage when they fall. Removal of deadwood may not be critical, but it should not be ignored.

Find Out More

Get tips on how to make your trees safer. Please consult with one of our arborists when you need advice or work done on your trees. Call us in Portland at 503-722-7267 and in Vancouver at 360-693-6056.

lean tree
5. This fungal conk is a sign of internal tree decay.
decay pocket 5. This oak tree with a large trunk wound is one example of a decay pocket.

trunk crack 6. Trunk cracks are not always obvious as in this tree. Be sure to inspect both the trunk and large branches.
hanger 7. Hanging dead branches in this Douglas-fir are likely to fall and should be removed immediately.

deadwood 8. Deadwood in this tree should be removed before failure occurs.

What you can do

  • Learn to spot the eight warning signs of structural tree defects
  • Inspect your trees regularly, and particularly during storm season, for warning signs
  • Call a certified arborist from Collier Arbor Care to examine the tree for remedy or removal
  • Remove anything (whether people, pets, or a picnic table) away from a potentially hazardous tree immediately

What a Collier Arbor Care Certified Arborist can do for you

# Lyle Feilmeier, certified arborist, uses the Resistograph™ to help detect and assess decay in trees.

# John Dale, certified arborist, prunes the Signature Oak Tree at the Oregon Garden. Crown cleaning removes deadwood, keeping trees healthy and safer

Depending on your tree care needs, a Collier Arborist might…

  • Thin crown-thick trees by removing 10-20% ofthe branches and foliage to reduce weight and wind resistance
  • Crown-clean trees to remove deadwood and hangers
  • Remove large leaning trees with cracked soil and exposed root balls
  • Remove or cable branches with V-crotches or weak branch attachments
  • Evaluate trees with large cavities, structural problems, or extensive trunk or root decay and remove if deemed hazardous
  • Recommend actions for long term tree care and health

Trees are alive. Their integrity and stability change over time. Inspect your trees regularly to ensure their longevity and health.