Its elegant white flowers line city streets to signal the arrival of spring, but this once-popular plant has become a threat to eastern ecosystems. The Callery pear tree has been considered an invasive tree for years, but effective Jan. 1, Ohio became the first state to ban the planting and distribution of this ornamental tree.
The Callery pear (Pyrus calleryana) is native to Asia and was brought to North America by USDA scientist Frank Meyer in the early 1900s. At first, this particular variety of pears was a godsend. Fire blight is a common bacterium on pears that has spread across the country. The species is resistant to the disease, easing the financial burden on struggling farmers. This popular species is also known for its ability to thrive in a variety of environments, making it a popular adaptable plant.
Although the new plant was promising, serious problems arose, especially as the tree grew older. Ed Kapraly, owner of local tree farm Riverside Native Trees and Nursery, said the plants currently have few positive attributes.
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“Take the Callery variety Bradford pear, for example,” he explains. “It is very fragile and poses a safety risk to people and their property. New varieties have been developed to address this problem, but in general the plant grows much faster than native plants. This is valuable for these plants such as sunlight Resources pose a risk.”
As new varieties of the Callery pear were created, scientists began to observe the invasive nature of the plant. Callery pears were initially praised for their inability to self-pollinate, which theoretically prevented their invasion. It was discovered that these new varieties were able to cross-pollinate when in close proximity to each other. This results in undesirable effects such as thorns and fruits whose seeds are easily spread by birds.
“We are seeing a lot of pears now but don’t know what to do with them because they are difficult to remove,” Caprari said. “It’s not that easy to cut them down. The roots can only be removed when the tree is young, and even then it’s difficult.”
Removal can be done by consulting a local arborist, but these options are often costly. Caprari said the easiest way to remove a tree is to cut it as close to the roots as possible and treat it with a high-concentration glyphosate solution of at least 25 percent.
For those who miss this popular tree, there are many local alternatives. Kapraly offers a few suggestions, including Black Tupelo and Serviceberry.