GARDENING IN IOWA

How to tell if that tree or shrub be saved after the derecho

From the Ground Up | Linn County Master Gardeners

A female cardinal perches on a downed tree in Cedar Rapids after a powerful storm with straight-line winds moved through
A female cardinal perches on a downed tree in Cedar Rapids after a powerful storm with straight-line winds moved through Iowa on Monday, Aug. 10, 2020. (Liz Martin/The Gazette)

When the debris is removed from your property, the damage to the remaining trees and shrubs becomes clear.

The Aug. 10 derecho sliced through tall canopy trees with 1 foot to 3 feet diameter trunks, causing them to buckle and break at about 8 feet to 10 feet. Trees with trunks that are 3-feet in diameter and bigger had their limb foliage and the branches torn apart at the top, or were literally pulled from the ground, roots and all. Unfortunately, there is no way to dependably save an uprooted tree.

When in doubt about a broken (30-feet up) canopy tree — if it could fall — have it removed. At least 50 percent of the canopy foliage must be green and viable to provide nutrients for ongoing health. If the tree is solid, had no previous damage and has an extensive root system, the jagged limbs can be pruned and then left. You can evaluate the health of the tree after the dormancy of winter, checking it during spring budding.

Understory trees

The understory trees (those 25 feet or shorter) in Linn County have extensive foliage damage, although not as many were sliced down by the wind due to their height and flexibility. And some understory trees tend to lose their foliage during this time frame anyway. It’s recommended that you prune the damaged limbs and leave the tree for next spring’s assessment if it is in no danger of falling.

Shrubs

Again, the general guidelines for pruning should be suspended for this year due to damage. It is not an option to only prune a third or to prune after it blooms because it’s mostly gone or twisted up. If it was a favorite and you want to give it a chance, remove all damaged foliage and limbs at about 1 to 2 feet above the ground. Then wait until spring to assess it.

Wounds on a tree

If a tree wound is less than 4 inches in diameter, treatment should be confined to removal of loose bark or wood. Leave the wound exposed so that the tree can begin the natural process of callus formation and healing or sealing over. “Scribing” and dressings are NOT recommended.

Should you cable or brace?

Trees that have severe structural defects or that suffered serious damage can sometimes be saved by cable and bracing techniques. Cable and bracing should only be done by a professional arborist who is familiar with this technique. Improper cabling or bracing can result in damage to the tree and the creation of a living hazard.

One final word: Tree work can be dangerous and many tasks should be left to professionals. The intent here is to familiarize you with techniques, not teach the proper techniques of pruning. If possible, defer decisions about removing a tree or shrub until spring. Many trees and shrubs can be saved by allowing nature to take its course. If you have any doubts, call a professional tree service or arborist.

Remember: Leave some cutup trees and debris for burrowing and nesting bees and other pollinators.

Cost

The national average per tree for removal and cleanup is around $600. When finding a tree company (www.medcoiowa.org/forms/disaster-recovery), try to get references and always get a written estimate of service.

Next week Master Gardeners will focus on finding the best tree to replace the ones lost.

Call the Master Gardeners with questions at (319) 447-0647 or send questions and photos to linncountymastergardener@gmail.com.

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