CLEMSON, SC – In the distance, next to a brick house in a nice subdivision, the trees rose over a wooden fence and showed everything that had made the Bradford bulb so attractive: They were towering and robust and had in the early spring white flowers that transformed their limbs into perfect clouds of cotton.
But when David Coyle, a professor of forest health at Clemson University, stopped in his pickup, he could see the monster these trees had spawned: a forbidden jungle that had devoured an open area nearby where the same white flowers bloomed uncontrollably in a bush of tangled branches studded with thorns.
“Once this tree grows somewhere, it does not take long to take it all over,” said Professor Coyle, an expert in invasive species. “It just dries everything out from under it.”
Beginning in the 1960s, when the suburbs sprouted over the south, clearing the ground of mazes of dead-end roads and garages for two cars, Bradford bulbs were the favorite trees. They were readily available, could thrive in almost any soil, and had an appealing shape with mahogany red leaves hanging deep into the fall and flowers appearing in early spring.
The popularity of the trees skyrocketed during a time of transformation as millions of Americans moved in search of the comfort and order that suburban neighborhoods were designed to provide. “Few trees have all the desired properties,” the gardening declared in the pages of The New York Times in 1964, “but the Bradford ornamental bulb comes unusually close to the ideal.”
But despite all this promise, the trees posed an unmanageable threat, one that has annoyed botanists, homeowners, farmers, naturalists, utilities and officials in a growing area of the country across the East Coast and reaching into Texas and the Midwest.
In South Carolina, the fight has intensified. The state is in the process of excluding the sale and trade of the trees and will be the second to do so. Professor Coyle, who tracks plants and insects that have invaded South Carolina and tries to limit their damage, has organized “bounty” programs in which people who bring evidence of a killed tree receive a native compensation in return.
The disadvantages of the Bradford bulb were initially subtle. Its white flowers, as beautiful as they were, emitted a foul odor that almost smelled fishy. But as the trees got older, more and more negatives appeared. They had a poor branch structure, leaving them prone to cracking and toppling in storms, sending limbs out on power lines, sidewalks and the roofs of homes they had to beautify.
But the most far-reaching consequence occurred when pear trees began colonizing open fields, farmland, riverbanks and ditches and rose between the pine trees along the highways from Georgia up through the Carolinas, removing the native species and growing ecosystems. The trees grow rapidly and climb to as high as 15 feet within a decade. (They can eventually reach 50 feet high and 30 feet wide.)
“You can not miss it,” said Tim Rogers, the day-to-day manager of a company that sells plants and supplies to landscaping companies. “It’s everywhere.”
The Bradford pear is a cultivar of the callery pear, which means that it is a variety produced by selective breeding – in this case, devise a tree that had no thorns from some other varieties and was undisturbed by pests.
But like the familiar plot of science-fiction stories, the creation that seemed too good to be true was actually too good to be true. The Bradford bulb had been billed as sterile, but that was not entirely true. Two Bradford pears cannot reproduce, scientists said, but they can cross-pollinate with other pear trees, and their seeds are widely spread by birds.
It is the resulting pear growth that alarms the researchers: These trees spread rapidly, have thorns that are three or four inches long and cluster close together, disrupting the lives of insects and other plants. “It’s a food desert for a bird,” Professor Coyle said, noting that the trees do not sustain larvae and other herbivorous insects. “There’s nothing to eat there.”
The Callery pear, which is native to East Asia, was originally brought to the United States by federal researchers seeking a species that resisted rooting and could be bred with the European pear to boost fruit production. But scientists recognized its potential as an ornamental tree, which spurred the development of the Bradford bulb.
The tree’s popularity was largely concentrated in the southeast and along the Mid-Atlantic coast. But it has been planted all over the country with lawns and entrances to subdivisions and shopping malls.
“There are some places where I have seen entire campuses planted with this one tree,” said Nina Bassuk, professor and director of the Urban Horticulture Institute at Cornell University. “If you’re there in April, it’s just this sea of white.” But then she added, “Bradfords became a problem.” Aging trees fell apart, she said, and “we began to notice them in places where they were not planted.”
Officials in South Carolina added the Bradford pear to its State Plant Pest List this year, initiating a ban that takes effect October 1, 2024. Ohio is the only other state to have taken similar measures, with a ban beginning in 2023.
In other states, efforts to ban trees have met with opposition from the plant industry, researchers said, given how much nurseries depend on their hardiness by using it as a rootstock.
But in South Carolina, industry leaders said researchers convinced them alternatives were available. The decision was also easier because Bradford bulbs as a landscape tree had fallen in popularity. “This factory has been in decline for a really long time,” said Mr. Rogers, who is also the elected president of SC Green, an industry association.
In the past, customers had sought out the trees, though their problems became more prevalent. “I would call them a necessary evil in terms of furniture,” said Mr. Rogers. But those days are long gone. “It’s not even in our catalog,” he added.
Researchers and officials said the public is developing a more sophisticated understanding of the consequences that landscaping choices can have. They point to the southwest, where drought-friendly designs have grown in popularity as water has become more scarce.
In the south, many were already aware of the threat from invasive species, as the region has struggled with plants such as privets and most of all kudzu, the Asian wine described as the plant that ate the south, covering much of the landscape and fry. myths about the speed and scope of its growth.
Yet government officials and homeowners are left to contend with the countless Bradford bulbs planted this year earlier. One Saturday last month, Professor Coyle traveled to Columbia, the state capital, for the latest of the bounty exchanges he has organized across South Carolina.
A flatbed was loaded with dozens of native potted trees: Shumard oak, yellow poplar, persimmon, eastern red cedar, sweet bay magnolia. Professor Coyle noted that the trailer was parked in the shade of a Chinese pistachio, another non-native plant.
The dozens of people who signed up were able to collect one of the native trees in return for proof of a overcome pear tree. (A selfie posing with the tree was sufficient.)
Valerie Krupp had printed photographs of the Bradford bulbs overturned in her yard and had destroyed her gutters and cut off the corner of her house. “I wish I had taken them out much sooner,” she said. She chose a live oak, a Shumard oak and a magnolia, and she said she looked forward to them growing and filling the void left by the pear trees. “I enjoyed the shade,” she said.
As Rick Dorn loaded his replacements into the trunk of his truck, he described the plagues by dealing with an attack of callery bulb. The thorns are perhaps the worst part. “They want to punch a hole in a tire,” he said.
His family owns an area of about 60 acres near Irmo, a suburb of Columbia. The ground has been overtaken by the trees, which, he noted, appeared around the same time as the subdivisions that now surround the property.
Professor Coyle believed that his efforts had made some progress: Hundreds of trees had been traded through the bounty programs, and he saw the ban as a major step. Yet the step-by-step progress was towards a force of nature.
“I know this is not going to be a quick fix,” Professor Coyle said. “To be honest, I’ll be working on callery pear throughout my career.”
But gradual progress was better than none at all.
“Leave for a while, man,” he said. “Gradually.”