China's Bradford Pear Is Quietly Taking Over America's Suburbs — And Nobody Can Stop It

[00:00:00]There is a tree in your neighbor's yard right now that the United States government helped put there. It was sold to the public as the perfect tree, neat and tidy and disease resistant, beautiful in spring. Cities planted it by the tens of thousands. Suburbs planted it by the millions. Landscape architects called it a breakthrough.

[00:00:22]Nurseries could not keep up with demand.

[00:00:25]And for about 20 years, [music] everybody was right. The Bradford pear was exactly what it looked like, a triumph of American horticulture.

[00:00:35]Then something happened that nobody predicted. The trees started getting out of the yards.

[00:00:41]Today, ecologists at universities across the eastern United States are calling it one of the worst botanical decisions in modern history.

[00:00:51]The Bradford pear is now spreading through forests, fields, and [music] roadsides in at least 27 states.

[00:00:59]It is choking out native species.

[00:01:01][music] It is altering soil chemistry.

[00:01:05]And because of how it reproduces, it is essentially impossible to eradicate.

[00:01:11]The people who planted [music] it are now being asked to cut it down.

[00:01:15]Some states are banning it outright.

[00:01:18]And the tree does not care.

[00:01:21]This is the story of how America fell in love with a tree that was quietly destroying everything around it.

[00:01:27]>> [music] >> And why the people who should have stopped it never did.

[00:01:33]The Bradford pear has a formal name, >> [music] >> Pyrus calleryana. It is a cultivar developed from a wild pear species native to China and Vietnam.

[00:01:43]The original plant, called the callery pear, was brought to the United States in 1909 by the plant explorer Frank Nicholas Meyer, the same man who introduced the Meyer lemon to American kitchens.

[00:01:56]His goal had nothing to do with landscaping.

[00:01:59]He was searching for rootstock [music] resistant to a bacterial disease called fire blight, which was devastating American pear orchards at the time.

[00:02:08]The callery pear had shown resistance in its native range, and Meyer shipped cuttings and seeds back across the Pacific.

[00:02:16]They arrived.

[00:02:17]They survived.

[00:02:18]And then they sat in government greenhouses for decades, largely forgotten, while researchers moved on to other problems.

[00:02:27]But in the 1950s, the USDA plant breeder John Creech and his colleague Frederick Lane began working with that callery pear material at the Glendale plant introduction station in Maryland.

[00:02:40]They were looking for an ornamental tree, something that could be deployed across the exploding post-war suburbs.

[00:02:47]America was building at a pace it had [music] never seen before, and every new development needed landscaping.

[00:02:54]Developers wanted something fast-growing, low-maintenance, [music] and attractive across all four seasons.

[00:03:01]The brief was simple: find a tree that makes a suburb look finished.

[00:03:06]In 1963, >> [music] >> the Bradford pear was introduced to the public.

[00:03:11]It was named after Frederick Charles Bradford, a former director of the Glendale station.

[00:03:17]It bloomed [music] white in spring.

[00:03:20]It turned deep red in autumn.

[00:03:23]It grew quickly into a neat oval shape that fit perfectly under power lines and beside parking lots.

[00:03:30]It required almost no care.

[00:03:32]The USDA promoted it.

[00:03:35]Extension offices promoted it. Nursery catalogs promoted it.

[00:03:40]By the 1980s, it was the most commonly planted street [music] tree in the United States.

[00:03:46]In some suburban developments from Virginia to Ohio, it was the only tree planted at all.

[00:03:53]Drive through any American suburb developed between 1970 and 2000, and the Bradford pear will be there, lining the entrance roads, punctuating the cul-de-sacs, >> [music] >> standing in perfect white rows every April.

[00:04:08]>> [music] >> There was one problem the developers knew about from the beginning.

[00:04:12]The Bradford cultivar was self-sterile.

[00:04:15]The trees could not pollinate each other to produce viable seed.

[00:04:19]Nurseries saw this as a feature, not a flaw.

[00:04:23]A tree that [music] cannot reproduce means a tree you have to keep buying.

[00:04:27]And for a while, the sterility held.

[00:04:31]But the Bradford pear was not the only Callery pear cultivar being developed.

[00:04:36]Over the following decades, nurseries and breeders introduced dozens of new varieties, [music] including Chanticleer, Aristocrat, Red Spire, and Cleveland Select.

[00:04:47]Each one was bred for slightly different ornamental traits.

[00:04:51]Each one was [music] technically a different cultivar.

[00:04:54]And when two different Callery pear cultivars bloom within range of each other, cross-pollination becomes possible. The sterility disappears, and the trees begin producing seed.

[00:05:07]American suburbs had spent 30 years planting millions of those trees within blocks of each other.

[00:05:14]The trees were now cross-pollinating freely.

[00:05:18]Birds were eating the small fruits and flying into woodlands and open fields.

[00:05:23]And the seeds were germinating with [music] extraordinary vigor.

[00:05:28]Brian Grayson, an ecologist with the Ohio Department of Natural Resources, described what he observed in a 2019 paper as a cascade.

[00:05:38]Individual escapes from the 1990s had grown into thickets.

[00:05:42]Those thickets were now producing enough seed to colonize surrounding land at scale.

[00:05:48]By the time his team began systematic surveys, callery pear was already established as an invasive species across the [music] entire Eastern Seaboard.

[00:05:58]Grayson noted that the process had reached what invasion biologists call the lag phase exit.

[00:06:05]The point at which a population has built enough critical mass that exponential spread becomes self-sustaining [music] without any further introduction from outside.

[00:06:16]In plain terms, the problem had already escaped.

[00:06:19]What makes the callery pear particularly destructive is not just that it spreads, it is how it spreads and what it does when it arrives.

[00:06:28]>> [music] >> The tree leafs out early, earlier than almost any native species in North America.

[00:06:34]In states like Ohio, Indiana, and Virginia, callery pear begins putting out leaves in late February or early March, weeks before oaks, maples, and native understory plants break dormancy.

[00:06:48]It seizes the light before the competition wakes up, and then it holds that canopy well into November.

[00:06:56]The growing window for native plants underneath is compressed [music] from both ends.

[00:07:01]Wildflowers that depend on spring light, trilliums, bloodroot, wild ginger, find that light gone before they can complete their reproductive cycle.

[00:07:13]The thorns are the second problem. Wild callery pear, the kind now escaping into roadsides and forest margins, grows thorns that can be 4 in long and dense enough to make a thicket genuinely impenetrable.

[00:07:28]Jim Chatfield, a horticulture educator at Ohio State University, has compared walking into a mature callery pear thicket to walking into razor wire.

[00:07:40]Deer cannot browse it. Humans cannot easily remove it by hand.

[00:07:45]And once a thicket establishes, the root system is deep and persistent.

[00:07:51]Cut one down and it sends up sprouts from the stump.

[00:07:55]Treat the stump with herbicide and the surrounding root network may still send up new growth from lateral roots several feet away.

[00:08:03]But the third problem is the one researchers find hardest to communicate to the public because it is invisible.

[00:08:12]Callery pear forms mycorrhizal associations with soil fungi, but the associations it forms are not the same as those formed by native species.

[00:08:23]In areas where Callery pear has colonized, researchers at Penn State documented changes in the soil fungal community within a single growing season.

[00:08:33]The fungal networks that native tree seedlings depend on for establishment are being disrupted.

[00:08:39]In heavily invaded sites, >> [music] >> native tree recruitment, the process by which new native trees establish from seed, dropped by more than 60% in some study plots.

[00:08:51]The land looks fine from the road. The trees are green. The fields appear full.

[00:08:57]But the ecological machinery underneath is being rewired.

[00:09:01]And when the Callery pear eventually senesces, there will be nothing native waiting to replace it.

[00:09:08]Douglas Tallamy, an entomologist and professor at the University of Delaware, who has spent decades [music] studying how native insects depend on native plants, has put numbers to exactly this problem.

[00:09:21]A native oak supports around 500 species of moth and butterfly caterpillars.

[00:09:27]A native black cherry supports more than 300.

[00:09:31]When Tallamy and his students searched Callery pear trees for for they found one species. [music] In areas where invasive plants like Callery pear had displaced [music] native vegetation, Tallamy's team documented losses of more than 90% of caterpillar populations compared to native-dominated sites.

[00:09:52]Caterpillars are not a side note in [music] this story.

[00:09:55]They are the protein base of the songbird food web.

[00:09:58]A single pair of chickadees requires between 6,000 and 9,000 caterpillars to raise one clutch of young.

[00:10:07]A forest edge colonized by Callery pear is, to a breeding warbler or a nesting [music] thrush, a food desert wearing the visual appearance of a healthy woodland.

[00:10:19]The damage does not show up in a soil sample. It shows up in the silence.

[00:10:25]Ohio banned the sale of Callery pear in 2023, followed by Pennsylvania, South Carolina, and several other states working bands through their legislatures. A wave of regulatory action that would look [music] decisive if it were not arriving 30 years after the critical window closed.

[00:10:44]But the bands face a problem the scientists involved are willing to discuss openly. [music] It is already too late for containment.

[00:10:53]Guy Sternberg, a dendrologist and co-author of Native Trees for North American Landscapes, put it this way in an interview with the American Nurseryman magazine.

[00:11:04]He said the effort was not a battle that could be won by legislation, [music] but a managed retreat.

[00:11:12]The wild Callery pear population in the Eastern United [music] States no longer depends on nursery sales. It is self-sustaining. It is expanding.

[00:11:22]And because individual trees can live for 40 or 50 years, the seed rain from established populations [music] will continue for decades, even if every nursery stopped selling the cultivars tomorrow, which they have not.

[00:11:37]In 2022, a survey found that Callery pear cultivars were still available for purchase in 38 US states, including several [music] states that had already identified it as invasive.

[00:11:50]The ornamental market for [music] the tree remains in the hundreds of millions of dollars annually.

[00:11:56]Nurseries with existing stock have lobbied successfully [music] against bans in multiple states, arguing that sell-through periods of 3 to [music] 5 years are necessary to avoid financial harm.

[00:12:08]The tree that [music] was planted with government assistance is now being defended against government removal by the same industry that government [music] helped build.

[00:12:17]The homeowners caught in the middle have received letters they did [music] not expect.

[00:12:22]In Ohio, the Department of Agriculture sent notifications [music] to municipalities that had planted Bradford pears as street trees, informing them that replacement was now recommended.

[00:12:34]Several cities, including Columbus and Cincinnati, [music] have begun active removal programs.

[00:12:40]The trees come out and are replaced with oaks, serviceberries, and native cherries.

[00:12:46]The cost per tree, including removal and replacement, runs between $300 and $800, depending on size and location.

[00:12:56]In Columbus alone, the city estimates it will need to remove and replace more than 4,000 street trees over the next decade.

[00:13:05]The trees that escaped [music] into the countryside are not being addressed at that scale.

[00:13:11]A roadside thicket of Callery pear in rural Indiana is simply there, and it will remain there, and in 15 years it will be larger.

[00:13:20]There is no budget for what comes next, and no mechanism to stop it.

[00:13:26]There is something worth sitting with the shape of this story.

[00:13:30]The Bradford pear was not planted [music] by careless people.

[00:13:34]It was planted by city planners following USDA guidance.

[00:13:39]It was planted by developers following landscape architect recommendations.

[00:13:44]It was planted by homeowners who were told by the people whose job it was [music] to know that this was the responsible, beautiful, durable choice.

[00:13:55]The mistake was not [music] made in ignorance.

[00:13:57]It was made by the institutions whose entire purpose was to prevent exactly this kind of mistake.

[00:14:05]Lindsey Borthwick, a restoration ecologist at the University of Tennessee who has studied callery pear invasion in the Cumberland Plateau region, noted in a 2021 [music] paper that the Bradford pear case illustrates a structural failure >> [music] >> in the ornamental plant introduction process.

[00:14:25]There was no mandatory ecological risk assessment prior to public release.

[00:14:31]There was no post-release monitoring requirement. [music] There was no liability mechanism if a promoted species later caused documented harm.

[00:14:40]The regulatory gap that allowed the Bradford pear to be deployed at landscape [music] scale is the same gap that exists today for dozens of other ornamental species currently in commercial production.

[00:14:51]The tree in your neighbor's yard may still be the Bradford cultivar. It may still be technically sterile on its own, but somewhere within a mile of that tree, there is almost certainly another callery pear cultivar in bloom at the same time in spring.

[00:15:07]The cross-pollination has already happened.

[00:15:10]The birds have already eaten the fruit.

[00:15:12]The seeds have already fallen in a field or a forest margin or a roadside ditch that nobody is watching.

[00:15:20]And in 3 to 5 years, >> [music] >> there will be a seedling there that nobody planted, nobody wanted, and nobody can easily remove. And it will outlast the tree in your neighbor's yard by several decades.

[00:15:34]The most instructive thing the USDA has published about the Bradford pear in the last 10 years is a single line on their own invasive species database.

[00:15:43]>> [music] >> It reads, "Do not plant."