Photo courtesy of Christine Casey,
North Carolina State University
Trees that aren't strong enough to "take it" in central Plains weather extremes became obvious last January. The worst ice storm in south central Kansas' recorded history brought the area to its knees as tree limbs crashed into power lines, buildings and vehicles – creating enough broad-scale damage to qualify it as a federal disaster area.
But, while the storm made firewood from decades of summer shade,songbird habitat, rope swings, and overall property value, it also taught important lessons. During the cleanup, Bob Neier, Kansas State University horticulturist, surveyed area residents to discover those lessons' specifics.
"The most extensive damage was to our old Siberian elms. They accounted for 30 to 80 percent of the loss in older sections of Wichita and in surrounding towns and rural homesteads," he said.
Neier found, however, that other trees proved to be less than sturdy, too. The list was surprisingly short, but included the Bradford pear, Russian olive and willow – including the Austree. Because area residents would be thinking about replacing trees this spring, Neier also identified the species that had survived with the fewest lasting effects – what he thinks of as the "strong trees."
"No species came through without damage to isolated, individual specimens. Still, many trees had no real damage or developed minor problems that can be cured with corrective surgery," he said.
As part of that, Neier discovered tree age, health, and past care had a big effect on damage level.
"Older trees broke more often than younger ones did," he said. "At the same time, however, trees that had been pruned regularly – training them to develop strong branch angles – held up the best."
For most deciduous trees, the strongest branch angle is almost straight out (90 degrees) from the trunk, Neier said. Branches that grow close to the trunk, forming an angle like a narrow "V," don't have to develop much strength during the good times, so are less likely to survive ice storms and strong winds.
Other factors that tended to make the area's trees vulnerable included:
- Never pruned.
- "Topped out" to restrict growth in height.
- Still retained seedpods or dead leaves.
- Already was declining due to age, disease, insects, lack of nutrients, or previous mechanical damage (often from repeated contact with a lawn mower or weed trimmer).
- Had many fine-textured branches.
The following species survived the storm came with the least damage, Neier said. (Residents in other areas can find out whether the species are appropriate where they live by checking with their state land-grant university's local Extension office.) Most have high odds for returning to excellent condition with corrective pruning.
- Bald cypress
- Chinese pistache
- Kentucky coffeetree
- Maple, amur
- Maple, autumn blaze
- Maple, red
- Maple, Shantung
- Maple, sugar
- Oak, bur
- Oak, red
- Oak, shingle
- Oak, Shumard
- Oak, swamp white
- Osage orange
- Pear, Aristocrat
- Pear, Chanticleer
- Pine, Austrian
- Planetree, London
- Zelkova (Japanese gray-bark elm)
Neier is based in the Sedgwick County Extension Education Center. He hopes area residents replacing trees next to utilities will choose strong species that also mature below power line height.
Neier and the county's Extension Master Gardeners are covering corrective pruning and tree selection among the educational seminars they're offering during the Wichita Garden Show, March 2-6. The Master Gardeners also will sell an illustrated, four-color publication on strong trees.