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oen among those that can and will “self-destruct” if not cared for. 2. ZELKOVA A close relative of the elm, the Japanese zelkova ( Zelkova serrata ), is oen used as an ornamental street tree . In its youth, these trees have smooth, gray bark, but as they mature, they shed this outer layer to reveal reddish-orange layers underneath. Unlike the Bradford pear, zelkovas have a much stronger branch structure and maintain sturdy branch unions. Instead, the problem for this species lies with its root system. “Encircling or gir- dling roots is a prob- lem with that species [zelkova] in particu- lar,” Buell explained. l [z lar When roots encircle the base of a tree, they strangle the trunk and can compromise nutrient transport from the roots. According to Buell, this type of root formation can also create structural vulnerabilities, such as significant leaning or swelling, and ultimately suffer a slow decline in health . Removal of encircling roots is oen tricky, and if not done correct- Unlike the Br have a m struct stur In f When base of a t trunk and can
Bradford pear trees are on the problem list for nearly every arborist. Its weak structure and destructive root system are the main culprits of its challenges. k .
roughly 15 percent, including “live, rubbing, and interfering branch- es, as well as dead branches 1” and larger.” Buell noted that some trees are just temporary, and Bradford pears are i l di
“Bradford pear is super weak,” Bill Bur- ley, CEO of Heli-Ax, said. Burley explained that Bradford pear has a characteristic shared by many problem trees: aggressive growth. He said it leads to brittle trees, which have an increased risk of failing, something the Bradford pear is well known for. In fact, it’s quite common that these trees begin to split under the weight of their own growth aer a couple decades, ac- cording to Theresa Culley, professor of biological sciences at the University of Cincinnati . Not surprisingly, with such fragile structure, Bradford pears require care- ful and close maintenance. “They can fail if they’re not managed,” Dane Buell, an arborist with 40 years of experience in the field, explained. Pruning has to be persistent so that the branches don’t become too heavy and begin to snap. Bartlett Tree Services recommends thinning the canopies
Left: Japanese zelkova tree. Right: When their roots encircle the base of a tree, they strangle the trunk and can compromise nutrient transport from the roots.
8 | Spring 2026 ArborTIMES ™
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