(NEXSTAR) — A stinky but handsome and widely popular landscape tree has become an aggressive invader.
Callery pears create dense thickets that overwhelm native plants and bear four-inch spikes that can flatten tractor tires.
Daniel Patterson, a sophomore at John Handley High School, walks home from school below blooming Bradford pear trees on Wednesday, March 30, 2016, in Winchester, Va. Their beauty and supposed sterility made Bradford pears a widely popular ornamental, but they wound up being pollinated by other ornamental varieties of Callery pears and turning highly invasive. (Jeff Taylor/The Winchester Star via AP) 
A callery pear is seen in Johns Creek, Ga. on Sunday, March 13, 2021. A stinky but handsome and widely popular landscape tree has become an aggressive invader, creating dense thickets that overwhelm native plants and bear four-inch spikes that can flatten tractor tires. (AP Photo/Alex Sanz) 
A Bradford pear tree, damaged by ice following an overnight winter storm, is seen in Wichita, Kan., on April 10, 2013. Their beauty and supposed sterility made Bradford pears a widely popular ornamental, but the deep Vs formed by some branches turned out to make them prone to breaking after 20 to 30 years. They also wound up pollinated by other ornamental varieties of Callery pears and turning highly invasive. (Mike Hutmacher/The Wichita Eagle via AP) 
Snow covers blossoms on a Bradford Pear tree in Roanoke, Va., Wednesday, March 21, 2018. Their beauty and supposed sterility made Bradford pears a widely popular ornamental, but they wound up being pollinated by other ornamental varieties of Callery pears and turning highly invasive. (Erica Yoon/The Roanoke Times via AP) 
This photo provided by David R. Coyle, shows spiky invasive Callery pear saplings in a horse pasture near Woodruff, S.C., on Jan. 20, 2020. Those only a few months old can bear spurs that endanger tractor tires, says Coyle, an assistant professor in Clemson University’s Department of Forestry and Environmental Conservation. (David R. Coyle via AP) 
A Callery pear tree is seen in Auburn, Ga., on Sunday, March 13, 2021. A stinky but handsome and widely popular landscape tree has become an aggressive invader, creating dense thickets that overwhelm native plants and bear four-inch spikes that can flatten tractor tires. (AP Photo/Alex Sanz) 
This photo made available by the U.S. Department of Agriculture National Agricultural Library, Special Collections, shows an unidentified man holding a spur of a large Callery pear tree next to a pine tree during an expedition to collect plants in China for the USDA, on March 31, 1917. The location, described as “near Nan chang yen, Hupeh, China,” may have been in Nanzhang county in Hubei. “Very few trees find pine trees congenial mates, but this remarkable Calleryana pear occurs at times quite plentiful in open pine forests, on sterile mountain slopes,” USDA plant explorer Frank N. Meyer wrote to his supervisor. Invasive varieties of Callery pear have been reported in at least 33 U.S. states. (Courtesy of USDA via AP) 
This photo made available by the U.S. Department of Agriculture National Agricultural Library, Special Collections, shows USDA plant explorer Frank N. Meyer on Mount Wutai, Shanxi, China, on Feb. 25, 1908. Meyer, who died in 1918, sent an estimated 2,500 species of plants, including his namesake Meyer lemon and Callery pears, to the United States. (Courtesy of USDA via AP)
Bradford pears and other ornamental Callery pears were cultivated from an import that saved pear orchards from a deadly bacterial disease. And for decades, the decorative trees seemed near perfect, aside from a tendency to fall apart after about 15 years — and their stench.
But they cross pollinated with other ornamental varieties.
Invasive stands now have been reported in more than 30 states. Fourteen states have formally listed the trees as invasive.
In Ohio, the tree is threatening and choking out many native trees and shrubs. It’s an extremely aggressive, non-native species, according to OSU Extension.
They are so invasive that the Ohio Department of Natural Resources has made purchasing the tree illegal beginning in 2023, but experts say that move is about 20 years too late.
The Pennsylvania Department of Agriculture has decided to place a phased ban on the Callery Pear, giving nursery owners time to draw down their inventories.
Missouri’s Department of Conservation is holding a buyback program for the tree. To qualify a property owner must a photo of a cut down pear tree in order to earn a free, less offensive, replacement tree.
The Associated Press contributed to this report.
