Pruning and spring care help winter-damaged trees
- Published: Thursday, Jan. 31, 2019
COLUMBIA, Mo. – This winter’s snow and ice took its toll on trees. Proper pruning now, followed by extra care in the growing season, gives trees a chance to grow back strong and healthy, says University of Missouri Extension horticulturist Michele Warmund.
Use patience and safety when checking damaged trees. Look up for limbs that might fall or for hanging utility lines. Clear broken limbs away from trees.
Evaluate trees for likelihood of survival and look at options, Warmund says. Consider replacement if 50 percent or more of the branches fell. Trees with exposed or broken root systems can’t be salvaged.
Leaning trees with trunk diameters of 6 inches or less might be saved. Bring them upright and securely fasten them to three or more stakes for trunk support. Recovery isn’t guaranteed, however. Underground root injury still may cause the tree to decline slowly and die.
Fungi and bacteria can infect trees with open wounds. Some healthy ornamental trees can wall off injured areas and grow callus tissue over wounds. Warmund says commercial products for wound damage are ineffective in preventing further injury.
Prune small branches in the area where they attach to larger-diameter limbs. Avoid stub cuts near the break.
Prune larger branches back to the trunk. Use a three-cut approach to prevent bark from tearing along the branch and to the trunk: 1. Make the first cut about 4 inches from the trunk. Cut only one-third of the way through from the underside of the limb. 2. Make the second cut about 6 inches from the trunk, starting from the top of the branch. This reduces weight on the part closest to the trunk. 3. Make the third cut near the trunk but outside of the branch collar.
Prune again after removing broken limbs to improve the tree’s structure and appearance. Do not “top” trees so that only major limbs are left. Limbs weaken or become prone to splitting when they have narrow crotch angles (less than 45 degrees) from the trunk or between two limbs. “Bradford pear trees are a good example of narrow crotch angles,” Warmund says. Also, remove limbs with bark growing between two branches.
Water trees during dry spells next growing season. “As a general rule of thumb, supplement rainfall to 1 inch of water per week,” she says. “Apply mulch less than 4 inches deep in a ring underneath the canopy and less than an inch deep near the trunk to save soil moisture.”
Light applications of granular fertilizer just before bud swell (around June 30) enhance recovery. Slow-release fertilizers also aid in recovery and growth. Base fertilizer amounts on soil tests and tree size. Warmund suggests no more than 2 pounds of nitrogen per 1,000 square feet during the growing season.
Consider damaged trees an opportunity to redesign landscapes and get rid of unwanted trees or invasive species such as Bradford pear.
“While we await the outdoor growing season, now is a good time to browse MU Extension guides, nursery catalogs and websites to find suitable replacement trees for planting when temperatures become favorable,” Warmund says.
For more information:
“Salvaging Trees After Heavy Snowfall,” Missouri Environment & Garden, January 2019, ipm.missouri.edu/MEG/2019/1/salvagingTrees.
“First Aid for Storm-Damaged Trees,” MU Extension publication G6867, extension.missouri.edu/G6867.
Writer: Linda Geist
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Published: Monday, Feb. 11, 2019