A Healthy Dose of Tree Work
by Peter R. Landau, ASCA Consulting Arborist, NEArborists.com
Winter is a great time for tree pruning for property owners with oak, maple, and other
types of trees on their property. The likelihood of spreading tree diseases is minimal
during the winter and the impact of pruning is also minimized while the tree is dormant,
before early to mid-April. In addition, without leaves the tree branch structure is easy to see
and mark for pruning. Broken, cracked, or hanging limbs are also easy to see and remove.
Homeowners and property managers are advised that tree failure is a major cause of property damage. An ice storm or high wind can cause a cracked tree to fail under its own weight. “Homeowners worried about trees falling and damaging property should call a professional arborist in for an inspection,” advises Peter Gerstenberger, senior advisor for safety, standards, and compliance with the Tree Care Industry Association. Gerstenberger notes that trees are designed to withstand storms, but all trees can fail—and defective trees fail sooner than healthy trees. A sound tree becomes potentially dangerous when the tree’s woody structure is weakened by one or more defects.
“To a professional arborist,” notes Gerstenberger, “defects are detectable signs that a tree has an increased potential to fail.”
One of the major warning signs of tree failure is a visible crack. Cracks form when the load exceeds the capacity of the stem to withstand the load. The vast majority of cracks are caused by improper closure of wounds, by the splitting of weak branch unions, or by flush-cut pruning. Cracks can occur in branches, stems, or roots. The wood behind the crack may be sound, decayed, or missing (cavity).
WHAT CAN YOU DO?
Cracks are hazardous when they compromise the structure of the tree by splitting the stem in two or when another defect, such as internal decay and a crack, do not provide enough sound wood in the outer shell to support the tree. Homeowners who would like a professional arborist to assess their trees should contact the International Society of Arboriculture (ISA).
Experts at the ISA urge homeowners to study a tree’s biology before whacking away. Improper trimming causes permanent damage and makes a tree more susceptible to disease.
Have a clear purpose in mind. Removing dead or diseased wood, providing clearance, or improving structure are common goals. Use clean, sharp tools and proper techniques. Small cuts do less damage than large ones. Tree wounds do not heal—they close. Make cuts just outside a branch collar (the connection to trunk or parent-branch tissue) for quick wound closure. Avoid leaving stubs.
Pruning large trees can be dangerous. If the job requires power equipment or climbing, consider calling a professional.
Mother Nature (snow, ice, wind, hail, lightning, and heavy rain) can cause significant damage to trees. Learning about how storms impact trees will allow you to develop preventative measures to decrease the chance of tree damage, as well as approaches to care for trees after a storm.
The first step is to determine if the damage is superficial or beyond repair. If more than 30 to 50 percent of the canopy and main branches are severely damaged, extensive repair is questionable. If a tree has lost more than 50 percent of its crown, the prospect of survival is poor.
Another type of damage occurs when young trees are bent over in ice storms or heavy snow. The recovery of the tree depends on the degree of bending and the length of time the tree remained in the bent position. Some trees will recover, some will not.
Trees often blow over because of root failure stemming from root rot diseases, shallow soils, soil compaction, construction damage, or saturated soil.
Salt used for clearing winter roads can be downright rotten for your trees, according to the tree experts at the ISA. “Excessive exposure to salt can cause widespread damage to your trees, leading to permanent decline and sometimes death,” said Jim Skiera, executive director of the ISA. “The problem with salt damage is that it might not show up on your trees until summer, when deicing salt is the last culprit you would suspect.”
To minimize the damage done to trees by deicing salts, use less salt, protect your trees from salt trucks on the street, plant salt-resistant trees, and improve soil drainage.
REPAIRING THE DAMAGE
If the damaged tree is large, it is best to contact a certified arborist or knowledgeable tree care company to complete the work. Before hiring a company check references, get more than one estimate, and make sure they carry proper insurance. If a company endorses “topping” in their advertisement or promotion, find another company.
If you plan to do it yourself, prune smaller branches back to the point where they join large ones, making a slanted cut next to a bud that can produce new growth. Large branches should be pruned back to the trunk or a main limb. Make the cut at the branch collar rather than flush with trunk.
Be alert for downed and damaged power lines. Do not attempt to prune trees that are near utility lines. Call in a professional.
Do not apply wound dressing. Research shows that dressings (e.g. tar, paint) do not prevent decay and may actually interfere with the healing process.
REDUCING TREE DAMAGE
All trees have the potential of being damaged in storms; however, future storm damage can be reduced through species selection and proper maintenance of trees.
Avoid selecting species that are fast growing, which makes them more susceptible to storm damage. A few examples include Bradford pear, silver maple, boxelder, white pine,and black locust. Better choices include white oaks, sweetgum, gingko, holly, linden, serviceberry, and arborvitae.
A winter survey of your property’s trees and shrubs should be performed annually. Mid-February to mid-April is the preferred time of year to prune many of these dormant deciduous plants since it is considerably easier to view their architecture and to observe damaged, diseased, or crossed branches before they leaf out. Damaged or diseased stems and limbs should be pruned as soon as they are noticed to prevent further injury and the spread of infections.
Staying on top of the health of your trees not only benefits the trees directly, it also helps ensure the enjoyment of your healthy forest for years to come. Your great grandchildren may climb the limbs of a grand oak someday, observing the healed wound of a cut great grandpa made.