Tree damage can come in many forms, and some may not be instantly apparent. Improper arboricultural practices, construction, utility work, landscaping, grounds maintenance, or irrigation can all lead to immediate or eventual tree damage. Other living organisms such as small animals, insect, and even other plants may also be responsible for damage. No matter the origin, damage must be handled carefully to preserve the tree and prevent hazards.
If you discover a tree that could be a hazard, consider hiring an ISA Certified Arborist to conduct a hazard tree assessment. If a tree has been deemed hazardous, keep people, pets, and vehicles out of the area until the hazardous condition has been corrected. Please contact an ISA Certified Arborist for assistance in remedying hazardous trees.
Signs of Problems
Soil often moves around or gets disturbed during construction. If dirt has been piled up in the Critical Root Zone during the construction process, return the grade to the original level as quickly as possible. Water the tree as needed; the roots have probably not received the moisture they needed while buried.
Visual symptoms of smothered roots include small yellow leaves, the presence of numerous suckers along the main trunk and branches, many dead twigs, and in some instances large dead branches. These symptoms may appear within a month or may not appear for several years.
If construction or other extensive disturbances occurred in the Critical Root Zone, severe root damage is likely. If roots have been severed, cut them cleanly with a hand saw. After any significant incursion into the root zone, have the tree examined by an ISA Certified Arborist. A professional arborist can make sure the tree doesn't have any stability issues as a result of cutting large roots.
Splits and Cracks
Inspect the trunk and large branches for cracks. Trunks with splits or cracks have a high failure potential. Deep, large cracks indicate structural weakness in the tree and need careful evaluation. Trees with multiple trunks or several branches attached to the same point on the trunk are at higher risk for splits or cracks. Tight V-shaped forks are more prone to break than open U-shaped unions. Inspect branches where they attach to the trunk.
Dead and Broken Branches
Dead branches, while a normal part of a tree’s growth pattern, will eventually fall. Branches over two inches in diameter can cause serious damage when they do. That's why dead branches should not be ignored. They should be pruned from the tree.
Hangers are broken branches still lodged in the tree. Whether partially attached or completely separated from the trunk, hangers are likely to fall and should be removed. Stubs left by broken branches should be pruned correctly.
Only prune or remove deadwood and hangers if you can do so safely from the ground. Otherwise for your own safety, please hire a professional.
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 problems. However, peeling bark and hollow areas don’t always mean a tree is unsafe.
Trees usually decay from the inside out, forming a cavity. Depending on the size of the cavity and the strength of the surrounding wood, the tree may be relatively sturdy. If there is dead wood in the cavity, don't scrape it out. This could expose live tissue and re-wound the tree. It's best to have the tree evaluated by an ISA Certified Arborist instead.
Unlike animals, trees have no wound healing process. Trees seal off damaged tissue rather than heal it. When a tree is injured, the cells in the surrounding area change chemically and physically to prevent the spread of decay. New cells then line the cut area to create a callus that covers and seals the injured area. This process is called “compartmentalization." How well the tree ultimately survives the wound will depend on how successful the tree is at compartmentalizing the damage.
Wounds should be left exposed so the tree can seal the injured area. If trees are wounded, remove injured bark by making shallow cuts with a sharp knife. Round the edges of the cut area. Only cut off the minimum necessary to remove the injured bark. Do not paint the wound. If the wound is deep, especially if it is mechanical damage, have an ISA Certified Arborist evaluate the tree to see if it is at risk for becoming a hazard.
Symptoms of Pests and Disease
The best way to protect trees from pests and disease is be proactive rather than reactive. Not all is lost if your tree is infested or infected. Catching symptoms early can prevent the loss of your landscape investment.
Look for the following:
- Root decay
- Dead branches in the crown
- Abnormally small or off-color leaves
- Serious trunk lean
- Cracked or mounded soil near the base of the tree
- Mushrooms or conks growing at the base of the tree
- Differences in color and growth between similar species of tree
- Large cankers - localized, sunken, barkless areas
- Sunburn or sunscaled damage (common in trees that prefer shade planted in full sun areas)
An ISA Certified Arborist can determine the seriousness of the disease and whether or not a more significant problem exists. If there is no hope for maintaining a healthy tree, you should consider removal.
Inspect Your Trees Annually
Like people, trees benefit from wellness checks that ensure they are thriving and healthy, as well as professional treatment when they exhibit signs of disease. Inspect trees annually for at least three to five years after planting or nearby construction. All trees need occasional inspections, but those that are young or have been disturbed need extra care.
Trees should also be inspected before and after high-risks events, such as storms. Larger trees have greater hazard potential than smaller trees. By inspecting your trees for warning signs, many potential problems can be mitigated before complications arise. As a general rule, trees cannot be cured of problems, but with proper care they may be preserved.