Tough to be a Tree

Last year it was the record cold temperatures and the duration of our cold that did so much damage to shade trees across Texas.

Last week’s cold spell wasn’t as bitter and it didn’t last as long, but it brought more clinging ice. Ice is heavy and it weights down trees’ branches. So we still saw a lot of damage, and I have a few short facts that will help you move through it.

• The damage was spotted across big parts of Texas. If this information doesn’t apply to you now, it likely will in some future time.

• Freezing rain always is a bigger threat than sleet. Rain coats leaves, twigs, branches and trunks – everything exposed. Sleet and ice pellets fall to the ground. Both are dangerous for walking and driving, but freezing rain does much more damage to trees. Wet snow is also a threat.

It’s been 40 years since live oaks in DFW saw this kind of major ice breakage (at least to my memory). It may be different in your part of Texas. This tree will require the help of a certified arborist to (A) remove the broken limbs properly and (B) reshape the tree. But it will look fine within a couple of years if given that help. Click image for larger view.

• Evergreen trees and trees that are covered by evergreen vines like English ivy are at much greater risk simply because they have so much more surface area to collect and hold heavy ice. My friend Steve Houser, certified arborist and owner of Arborilogical Services (a sponsor of this publication) tells me that their firm has seen the heaviest damage to live oaks, pines, eastern redcedars, cherry laurels and taller hollies.

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• Trees that were compromised by last winter’s cold were much more vulnerable to breakage in this year’s ice. Live oaks that suffered dieback and bark splitting come to mind first.

Ice and snow caused this large branch of an American elm to break and fall. Look closely and you’ll see that decay had set in on the top portion of the branch where another limb had broken years earlier. That old wound had not healed properly.

• Damage is always very common in trees with decay brought on by poor pruning practices (stubs left to heal improperly), corky burls (for example, caused by large clumps of mistletoe in cedar elms or hackberries), and narrow branch angles that don’t form strong unions (ornamental pears).

• Be extremely cautious in trying to do corrective pruning yourself if large, high limbs are involved. It’s always best to hire an ISA Certified Arborist (member of the International Society of Arboriculture).

Eastern redcedar branches along the Sperry driveway snapped from the weight of ice and snow. These were 20-foot-long branches and they have left serious stubs. First task was to clear the drive, but we’ll be coming back to cut the snags back flush with the trunk. We’ll leave perhaps 1/4-inch of branch collar in the process for quickest possible healing. No pruning sealant is needed for any species other than oaks.

• Leave no stubs. Cuts should be made almost flush with the remaining limb or trunk of the tree to ensure quickest possible healing.

• When trimming oaks, apply pruning sealant to prevent entry of oak wilt fungus into the open wound. The fungus is most active during the spring, so this step is essential.

• Do any additional pruning and corrective reshaping to restore attractive growth form to the damaged plants. Fertilize and water them to encourage good growth this spring.

Posted by Neil Sperry
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