What's bugging you? February 17, 2016

By Jim Leser


We all know the benefits of planting trees. Their number one benefit is to provide shade and beauty to our landscapes. But they can also be dangerous to life, limb or property. Winter is a good time to assess your older trees for potentially dangerous defects while leaves are off the trees.

Last September I participated in the 25th Western Colorado Community Forestry Conference that addressed tree risk awareness. While much of what was discussed was targeting professional arborists, I felt I gained a lot of helpful information as a Colorado Master Gardener that I could pass on to you, the homeowner.

Trees, or parts of trees, can fall, causing injury to people or damage to property. And one important point to keep in mind is that it is the tree owner's legal responsibility to provide for the safety of their trees. There is no defense for ignorance. In Colorado, if your tree injures someone or damages someone else's property, you are legally responsible. If you know you have a risky tree, this could result in negligence charges and even more legal headaches.

So being able to evaluate your tree defects associated with increased risk is very important. Even as important can be knowing what preventative tree care steps would reduce the risk of potentially defective trees.

While the accurate determination of tree risk is oftentimes the purview of a professional arborist trained in risk assessment, you can at least make a preliminary assessment. Things to consider include: 1) Are there any large dead branches in the tree? 2) Are there cavities or rotted areas in the trunk or major branches? 3) Are there any mushrooms or other obvious disease present at the base of the tree? 4) Have any branches previously fallen from the tree? 5) Are there cracks or splits in the trunk, especially where larger branches are attached? 6) Does the tree have a weak branching structure? 7) Is the tree leaning excessively? And 8) Has the root system been compromised through recent construction activities?

When evaluating tree risk, keep in mind that risk is a product of the likelihood of a tree or branch failure and the likelihood of people or property being targets of this failure. If people rarely are found near a defective tree, then its risk level could be greatly reduced. The same would apply to its proximity of property.

Homeowners can often avoid much of the risk associated with older trees at planting time through careful tree and planting site selection, using proper planting techniques, watching out for the development of insect pest and disease problems, and proper pruning and watering practices. Willows and silver maples are examples of high-risk tree species.

Yearly inspections of older trees should help detect potential defects before they become serious risk factors. While some risk management is within the scope of many homeowners, tree or large branch removal usually should be left up to the professional arborist. While these services can be expensive, any liability issues associated with your risky trees are usually much more costly. It is your choice. You can pay some money now or a lot more later. Tree risk problems are not going away on their own.

Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.