The last column discussed inspecting tree root zones and trunks. This installment focuses on the tree crown, hazard assessment, and corrective action. Remember, a tree is unsafe if it has a defect or condition that threatens people, places, or property.
The crown includes tree branches and foliage. Foliage assessment will have to wait until summer, but winter’s a great time to view overall tree structure.
Well-formed tree branching is similar to the drawings I laboriously created as a teenager where each branch was a bit smaller in diameter than the one it grew out of and the branches raised upwards like arms reaching for the sky. Poor architecture is a growth pattern that indicates weakness or structural imbalance. Trees with strange shapes may be interesting to look at or may provide an eerie spectacle on a dark Halloween night, but they could also be structurally defective.
Stand where you can see the entire tree if possible. Are there any horizontal branches that are as large as the stem they’re attached to? Over time it is possible the heavy side branch may split off from the tree.
Are there any hanging branches? If so, remove them immediately. Are there any branches that rub against one another? If so, consider removing one of those branches.
Cankers are areas on the stem or branch of a tree where the bark is sunken or missing. They are caused by wounds or disease. If a branch has a canker that encompasses more than half of its circumference, the branch may be hazardous, even if the exposed wood appears sound.
Cracks are splits in the wood. Deep cracks indicate that wood fibers have separated making the tree weaker. Cracks usually follow the wood grain (that is up and down). If you discover a crack, try to measure the length and depth of the wound. As a rule, the deeper and longer cracks pose a greater risk of failure.
In addition to looking at the health of a tree, take a look at its location. If a tree is near a road, driveway or alley, make sure it doesn’t block a driver’s view of people or other vehicles. As a frequent pedestrian in Alamosa, I get annoyed at trees or hedges that block sidewalks. Many towns have ordinances that require branches to be trimmed allowing for easy sidewalk access. Unfortunately, Alamosa is not so enlightened.
It may be hard to determine what, if any, action needs to be taken to correct tree hazards. If you’re not sure of a defect’s safety, get an expert opinion. This is easier said than done in the San Luis Valley. Most books and web sites suggest hiring a professional associated with an organization such as the International Society of Arboriculture. Unfortunately, none are listed in our area. If fact, last summer when the City Department of Parks decided to have an arborist evaluate trees in Cole and Boyd Parks, they had to hire one from Durango.
This doesn’t mean you can’t hire someone locally. But please be careful. I see a lot of improperly pruned trees around town – they are hacked off mid branch or seemingly at random points or even just topped (see the 2010 November 24 column “Don’t Top Trees, Please” at AlamosaTrees.net).
There are several questions you should ask when selecting an arborist. They include: What tree care training do you have? Do you have proof of insurance (i.e., person and property damage insurance)? Do you give written estimates? Can you give me references and contact information from past jobs? Take a look at their previous work and talk with past customers.
Much of the content for this column came from the United States Department of Agriculture’s publication “How to Recognize Hazardous Defect in Trees”, and from Auburn University’s “Homeowner’s Guide to Safer Trees.” For specific local species information, consult the lists at AlamosaTrees.net.
PRUNING WORKSHOP: The State Forest Service and Alamosa Tree Board are hosting a day-long Tree Pruning Workshop on Tuesday, April 19. Vince Urbina, Colorado State Forester, will present. The morning session will be classroom style and the afternoon session will be in the field. The workshop is limited to 20 people and the cost is $10, which includes beverages and a homemade lunch. For more information or to register call the State Forest Service office at 587-0915.
“The trees are drawing me near, I’ve got to find out why. Those gentle voices I hear explain it all with a sigh.” Moody Blues – “Tuesday Afternoon”.