Once the Callery Pear Tree was Landscapers’ Favorite — Now States Are Banning this Invasive Species and Urging Homeowners to Cut it Down

Ryan W. McEwan • March 28, 2023

When people think of spring, they often picture flowers and trees blooming. And if you live in the U.S. Northeast, Midwest or South, you have probably seen a medium-sized tree with long branches, covered with small white blooms – the Callery pear ( Pyrus calleryana ).

For decades, Callery pear – which comes in many varieties, including “Bradford” pear, “Aristocrat” and “Cleveland Select” – was among the most popular trees in the U.S. for ornamental plantings. Today, however, it’s widely recognized as an invasive species. Land managers and plant ecologists like me are working to eradicate it to preserve biodiversity in natural habitats.

As of 2023, it is illegal to sell, plant or grow Callery pear in Ohio. Similar bans will take effect in South Carolina and Pennsylvania in 2024. North Carolina and Missouri will give residents free native trees if they cut down Callery pear trees on their property.

How did this tree, once in high demand, become designated by the U.S. Forest Service as “ Weed of the Week ”? The devil is in the biological details.

A Kentucky extension specialist explains why Callery pears initially seemed like a solution, but have proved to be a major problem.

A quasi-perfect tree

Botanists brought the Callery pear to the U.S. from Asia in the early 1900s. They intentionally bred the horticultural variety to enhance its ornamental qualities. In doing so, they created an arboricultural wunderkind. As The New York Times observed in 1964 :

“Few trees possess every desired attribute, but the Bradford ornamental pear comes unusually to close to the ideal.”

Modern varieties of Callery pear produce an explosion of white flowers in springtime, followed by deep green summer foliage that turns deep red and maroon in autumn. They also are very tolerant of urban soils, which can be highly compacted and hard for roots to penetrate. The trees grow quickly and have a rounded shape, which made them suitable for planting in rows along driveways and roadsides.

Tree with leaves mostly shaded red.
A Callery pear turning red in fall. Ryan McEwan , CC BY-ND

During the post-World War II suburban development boom, Callery pear trees became extremely popular in residential settings. In 2005 the Society of Municipal Arborists named the “Chanticleer” variety the urban street tree of the year. But the breeding process that created this and other varieties of Callery pear was producing unexpected results.

Cloning to produce an American original

To ensure that each Callery pear tree had bright blooms, red foliage and other desired traits, horticulturists created identical clones through a process known as grafting : creating seedlings from cuttings of trees with the desired characteristics.

Grafting is a method for propagating new fruit trees using buds from existing trees and fusing them onto a branch or stem of another tree, which is called the rootstock.

This approach eliminated the messy complexity of mixing genes during sexual reproduction and ensured that when each tree matured, it would have the characteristics that homeowners desire. Every tree of a specific variety was a genetically identical clone.

Grafting also meant Callery pear trees could not make fruits. Some fruit trees, such as peaches and tart cherries, can fertilize their flowers with their own pollen. In contrast, Callery pear is self-incompatible: pollen on an individual tree cannot fertilize flowers on that tree. And since all Callery pears of a specific variety planted in a neighborhood would be identical clones, they would effectively be the same tree.

If a tree can’t produce fruits, it can’t disperse into natural habitats. Gardeners and landscapers thought it was perfectly safe to plant Callery pear near natural habitats, such as prairies, because the species was trapped in place by its reproductive biology. But the tree would break free from its isolation and spread seeds far and wide.

The great escape

University of Cincinnati botanist Theresa Culley and colleagues have found that as horticulturalists tinkered with Callery pears to produce new versions, they made the individuals different enough to escape the fertilization barrier. If a neighborhood had only “Bradford” pear trees, then no fruits could be produced – but once someone added an “Aristocrat” pear to their yard, then these two varieties could fertilize each other and produce fruits.

When Callery pear trees in gardens and parks started depositing seeds in nearby areas, wild populations of the trees became established. Those wild trees could pollinate one another, as well as neighborhood trees.

In today’s landscape, Callery pear is astonishingly fertile. The prolific flowering that horticulturists intentionally bred into these varieties now yields tremendous crops of pears each year. Although these little pears are generally not edible by humans, birds feed on the fruit, then fly away and excrete the seeds into natural habitats. Callery pear has become one of the most problematic invasive species in the eastern United States.

A thorny problem

Like other invasives, Callery pears crowd out native species. Once Callery pear seedlings spread from habitat edges into grasslands , they have advantages that allow them to dominate the site.

In my research lab , we have found that Callery pear leafs out very early in spring and drops its leaves late in fall. This enables it to soak up more sun than native species. We also have discovered that during invasion, these trees alter the soil and release chemicals that suppress the germination of native plants.

Callery pear is highly resistant to natural disturbances. In fact, when my graduate student Meg Maloney tried to kill the trees by using prescribed fires or applying liquid nitrogen directly to stumps after cutting the trees down, her efforts failed. Instead, the trees sprouted aggressively and seemingly gained strength.

Once Callery pear has escaped into natural areas, its seedlings produce very sharp, stiff thorns that can puncture shoes or even tires. This makes the trees a menace to people working in the area, as well as to native plants. Another nuisance factor is that when Callery pears bloom, they produce a strong odor that many people find unpleasant.

Currently, directly applying herbicides is the only known control for a Callery pear invasion. But the trees are so successful at spreading that poisoning their seedlings may simply create space for other Callery pear seedlings to establish. It is unclear how habitat managers can escape a confounding ecological cycle of invasion, herbicide application and re-invasion.

An open space studded with Callery pear trees, with dead grasses between the trees.
A Callery pear invasion is crowding out native species on this agricultural land, converting it to woodland. Oklahoma State University Extension , CC BY-ND

Banned but not gone

In response to work by the Ohio Invasive Plants Council and other experts, Ohio has taken the extraordinary step of banning Callery pear to thwart its ecological invasion into natural habitats. But the trees are common in residential areas across the state and have established vigorous populations in natural habitats. Ecologists will be working well into the future to maintain openness and biodiversity in areas where Callery pear is invading.

In the meantime, homeowners can help. Horticulturists recommend that people who have a Callery pear on their property should remove it and replace it with something that is not an invasive species. Few trees possess every desired attribute, but many native trees have visually attractive features and will not threaten ecosystems in your region.The Conversation

Ryan W. McEwan , Professor of Biology, University of Dayton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Common Sense for the Eastern Shore

By John Christie December 16, 2025
When I practiced law, much of my litigation involved issues arising under federal antitrust laws. The Department of Justice (DOJ) was my frequent adversary in court. In some cases, DOJ challenged a client’s conduct as anticompetitive. In others, they claimed an intended client merger would create a monopoly. Some of these DOJ court battles were won, others were not. Overall, I had great respect for DOJ lawyers. They were professional, well prepared, and dedicated to their mission of seeing justice done. They were courteous, honest, and forthright with the courts before which we argued our cases. In those days, without resorting to social media or press conferences, the DOJ spoke entirely through its court filings. Although as an advocate I took issue with various DOJ investigatory decisions as well as decisions to initiate litigation, I never thought politics was involved. Post-Watergate internal rules strictly limited communication with any figures at the White House. Not so, it seems, anymore. Beginning last January 20, all of this changed rapidly and spectacularly . On March 14, Trump triumphantly arrived at the main DOJ building in D.C. to be welcomed by a group of carefully selected VIPs. He was greeted by Pam Bondi, his chosen new attorney general, who exclaimed, “We are so proud to work at the directive (sic) of Donald Trump.” Bondi’s boast that the DOJ now worked at the president’s behest was something never said before and, in effect, surrendered the department’s long and proud independence. And Bondi’s comment was not an empty gesture. As chronicled by reporters Carol Leonnig and Aaron Davis in their new book, Injustice: How Politics and Fear Vanquished America’s Justice Department , within hours of being sworn in, Trump and his lieutenants began punishing those at the Justice Department who had investigated him or those he considered his political enemies. Career attorneys with years of experience under many administrations were fired or reassigned to lesser work, or they resigned. As Leonnig and Davis report, what followed was “the wholesale overthrow of the Justice Department as Trump insert[ed] his dutiful former defense attorneys and 2020 election deniers atop the department.” [Source: Injustice , p. xix.] In the place of years of experience, the new team appears credentialed simply by loyalty to the president’s causes. The DOJ’s conduct in court has since caused damage to judicial and public faith in the integrity and competence of the department. Just Security is an independent, non-partisan, daily digital law and policy journal housed in the Reiss Center on Law and Security at the New York University School of Law. Since January 20, it has documented federal judicial concerns about DOJ conduct. In 26 cases, judges raised questions about DOJ non-compliance with judicial orders and in more than 60 cases, judges expressed distrust of government-provided information and representations. This count was taken the day after a federal court dismissed the DOJ cases against former FBI Director James Comey and New York Attorney General Letitia James. [Source: Just Security , “The ‘Presumption of Regularity’ in Trump Administration Litigation,” Nov. 20, 2025.] As summarized by the Georgetown Law Center’s Steve Vladeck, “It’s one thing for the Department of Justice to so transparently pursue a politically motivated prosecution. But this one has been beset from the get-go with errors that remotely competent law students wouldn’t make. Indeed, it seems a virtual certainty that the Keystone Kops-like behavior of the relevant government lawyers can be traced directly to the political pressure to bring this case; there’s a reason why no prosecutors with more experience, competence, or integrity were willing to take it on.” [Source: One First , Nov. 24, 2025.] Rather than accept criticism and instead of trying to do better, Bondi’s DOJ and the Trump administration lash out in a fashion apparently aimed at demeaning the federal judiciary. At a recent Federalist Society’s National Lawyers Convention, Deputy Attorney General Todd Blanche, one of Trump’s former defense attorneys, attributed the Trump administration’s myriad losses in the lower federal courts to “rogue activist judges.” He added, “There’s a group of judges that are repeat players, and that’s obviously not by happenstance, that’s intentional, and it’s a war, man.” Deputy Chief of Staff Stephen Miller decries each adverse ruling against the Trump administration as just part of a broader “judicial insurrection.” Not to be left behind, Trump himself regularly complains of “radical left lunatic” judges. In addition to the harm these comments inflict on the federal courts, their premise is simply not true. According to a survey by Vladeck, as of Nov. 14, there were 204 cases in which federal district courts have ruled on requests for preliminary relief against the Trump administration. In 154 of them, district judges granted either a temporary restraining order, a preliminary injunction, or both. Those 154 rulings came from 121 district judges appointed by seven presidents (including President Trump) in 29 district courts. In the 154 cases with rulings adverse to the Trump administration, 41 were presided over by 30 Republican-appointed judges, fully half of whom were appointed by President Trump. No, it is no longer your grandfather’s Department of Justice. John Christie was for many years a senior partner in a large Washington, D.C. law firm. He specialized in anti-trust litigation and developed a keen interest in the U.S. Supreme Court about which he lectures and writes.
By CSES Staff December 16, 2025
The Salisbury City Council has appointed longtime public servant Melissa D. Holland to fill the vacancy in District 2. Holland was selected on Dec. 1 after the council reviewed several applicants. A 27-year resident of Salisbury, Holland brings more than 20 years of experience in government, education, and administration. As executive assistant to the president of the University of Maryland Center for Environmental Science, she currently oversees operations, budgeting, communications, and planning. Before joining UMCES, Holland worked for nearly 11 years with the Wicomico County Council, gaining extensive experience in legislative procedure, constituent services, research, and budget preparation. Her background includes positions with the Wicomico County Board of Education, the State of Maryland’s Holly Center, and multiple early-learning programs. Approved by a 3-1 council vote, Holland was selected based on her administrative expertise and long-standing community involvement. (Salisbury’s City Council is now comprised of only women.) She has a bachelor’s degree in legal studies from Post University and an associate degree from Wor-Wic Community College. She has also served as PTA president at East Salisbury Elementary and Wicomico Middle School. In her application, Holland emphasized her commitment to maintaining transparency in city government and ensuring that District 2 residents remain informed and represented. “I plan to be well-informed on the issues that matter to the citizens of Salisbury and to listen to their concerns carefully,” she wrote. “I want to make a positive and lasting impact on our city.” Holland’s appointment restores the City Council to full membership as it faces debates over budgeting, infrastructure planning, and local governance initiatives. She is expected to begin constituent outreach immediately and participate fully in the selection of the next council president.
By CSES Staff November 4, 2025
Voters in Hurlock have delivered sweeping changes in this year’s municipal election, as Republican and GOP-aligned candidates won key races there. The results mark a setback for Democrats and a significant political shift in a community that has historically leaned Democratic in state and federal contests. The outcome underscores how local organizing and turnout strategies can have an outsized impact in small-town elections. Analysts also suggest that long-term party engagement in municipal contests could shape voter alignment in future county and state races. Political analysts warn that ignoring municipal elections and ceding them to the GOP could hurt the Maryland Democratic Party in statewide politics. Turnout increased by approximately 17% compared with the 2021 municipal election, reflecting heightened local interest in the mayoral and council races. Incumbent Mayor Charles Cephas, a Democrat, was soundly defeated by At-Large Councilmember Earl Murphy, who won with roughly 230 votes to Cephas’s 144. In the At-Large Council race, Jeff Smith, an independent candidate backed by local Republicans, secured a 15-point win over Cheyenne Chase. In District 2, Councilmember Bonnie Franz, a Republican, was re-elected by 40 percentage points over challenger Zia Ashraf, who previously served on the Dorchester Democratic Central Committee. The only Democrat to retain a seat on the council was David Higgins, who was unopposed. The Maryland Republican Party invested resources and campaign attention in the Hurlock race, highlighting it on statewide social media and dispatching party officials, including Maryland GOP Chair Nicole Beus Harris, to campaign. Local Democrats emphasized support for Mayor Cephas through the Dorchester County Democratic Central Committee, but the Maryland Democratic Party did not appear to participate directly.
By CSES Staff November 4, 2025
In what political observers are calling a clear break from Maryland’s moderate Republican establishment, Wicomico County Executive Julie Giordano chose former Gov. Bob Ehrlich — not former Gov. Larry Hogan — as the guest of honor at her re-election fundraiser in late October. Billed as Giordano’s annual Harvest Party, her event drew conservative activists from across the lower Eastern Shore and featured Ehrlich as keynote speaker. This was immediately read by insiders as a signal that Giordano will embrace the party’s right-wing base ahead of 2026, distancing herself from Hogan’s more centrist, bipartisan image. “Bringing in Bob Ehrlich instead of Larry Hogan wasn’t accidental,” one longtime Republican strategist said. “It shows Giordano wants to plant her flag with the MAGA-aligned wing of the party, the same voters who now dominate Maryland’s Republican primary base.” Hogan, who has hinted at another run for governor, was notably absent from this year’s Tawes Crab and Clam Bake in Somerset County, a high-profile gathering long considered essential for statewide contenders. Coupled with Giordano’s public alignment with Ehrlich, Hogan’s absence has fueled speculation that his influence within Maryland’s GOP is slipping. Those doubts were amplified by new polling data. A statewide survey commissioned by the Baltimore Banner found Gov. Wes Moore (D) leading Hogan 45% to 37% in a hypothetical 2026 matchup, with 14% undecided. The poll, conducted by phone and web from Oct. 7–10 among more than 900 registered voters, carries a margin of error of 3.2 percentage points. The results suggest that while Hogan remains popular among moderates and independents, Moore continues to hold a firm advantage statewide, particularly among Democrats and younger voters. Giordano’s decision to align herself with Ehrlich rather than Hogan further illustrates the ideological divide defining Maryland Republicans heading into 2026. As the party drifts further to the right, analysts say Hogan’s brand of pragmatic centrism may no longer have a natural home in today’s GOP. For now, Ehrlich’s appearance in Salisbury is being seen as a symbolic moment, one that cements Giordano’s status as a leading figure in the state’s Trump-aligned movement and underscores how quickly the political winds have shifted. For Hogan, once seen as the Republican best positioned to reclaim the governor’s office, that shift may mark the end of an era.
By Jan Plotczyk November 4, 2025
Can Maryland create a new congressional map that will flip the state’s sole Republican district to the Democrats? Gov. Wes Moore has created a Governor's Redistricting Advisory Commission to consider mid-cycle redistricting and Maryland has jumped into the redistricting fray. The commission will conduct public hearings, solicit public feedback, and present recommendations to the governor and Maryland General Assembly. “My commitment has been clear from day one — we will explore every avenue possible to make sure Maryland has fair and representative maps,” said Moore. “And we also need to make sure that, if the president of the United States is putting his finger on the scale to try to manipulate elections because he knows that his policies cannot win in a ballot box, then it behooves each and every one of us to be able to keep all options on the table to ensure that the voters’ voices can actually be heard .” Moore’s commission is one of those options — a response to Trump’s call to Republican-led states to create more GOP House districts before the 2026 midterm elections. Three GOP states — Texas, Missouri, and North Carolina — have completed a Trump gerrymander for a gain of seven seats and three more states — Indiana, Utah, and Ohio — could create new maps with a total of four additional Republican seats. That would make 11, should they withstand challenges. Democratic-led states made a lot of noise at first about countering these GOP efforts, but only California and Virginia have campaigns for new maps underway. California wants to flip five seats and Virginia hopes for up to four. Optimistically, that could add up to as many as nine. Maryland’s goal would be to add one Democratic seat. Other states on both sides could soon follow, in some cases taking advantage of existing redistricting deadlines or ongoing litigation. Maryland State Senate President Bill Ferguson (D-Balto City) is not in favor of mid-cycle redistricting, calling it too dicey. “Simply put, it is too risky and jeopardizes Maryland’s ability to fight against the radical Trump administration. At a time where every seat in Congress matters, the potential for ceding yet another one to Republicans here in Maryland is simply too great,” Ferguson wrote in a letter to Senate Democrats. Rep. Andrew P. Harris (R-MD01), whose district would be targeted by redistricting, called the effort "the most partisan thing you could do." He whined, “It just wouldn’t be fair.” Harris warned that any redistricting could backfire on the Democrats. “We will take this to court, it will go as high as necessary, and in the end, a judge could draw a map that actually has two or three Republican congressmen,” Harris said. “I’d caution the Democrats, be careful what you wish for.” Harris and his wife, Maryland GOP Chair Nicole Beus Harris, have perhaps already worked out a strategy. The Governor’s Redistricting Advisory Commission, last constituted by Gov. Martin O’Malley in 2011, will begin its work this month. The five-member commission includes: Chair: Senator Angela Alsobrooks Senate President Bill Ferguson or designee Speaker Adrienne A. Jones or designee Former Attorney General Brian Frosh Cumberland Mayor Ray Morriss “We have a president that treats our democracy with utter contempt. We have a Republican party that is trying to rig the rules in response to their terrible polling,” said Sen. Alsobrooks. “Let me be clear: Maryland deserves a fair map that represents the will of the people. That’s why I’m proud to chair this commission. Our democracy depends on all of us standing up in this moment.” Will Maryland’s First District finally be competitive? Can we at long last replace “AWOL Andy” Harris? Stay tuned…. Jan Plotczyk spent 25 years as a survey and education statistician with the federal government, at the Census Bureau and the National Center for Education Statistics. She retired to Rock Hall.
By CSES Staff November 4, 2025
In strong numbers, local residents turned out last month for a community information session on offshore wind hosted by the Alliance for Offshore Wind at the Ocean Pines library. The forum heard from industry experts, environmental advocates, and labor leaders to discuss how offshore wind projects can support jobs, clean energy, and coastal resilience along Maryland’s Eastern Shore. Featured were Sam Saluto of Oceantic, Jim Strong of the United Steelworkers, Ron Larsen of Sea Ink Solutions, and Jim Brown of the Audubon Society, all of whom emphasized the long-term environmental and economic benefits of wind development off Maryland’s coast. Speakers outlined how the project, once completed, is expected to create hundreds of high-paying jobs, generate clean power for tens of thousands of homes, and reduce reliance on fossil fuels that cause pollution and coastal erosion. “The potential here is extraordinary,” said Saluto, highlighting Oceantic’s ongoing work to ensure safety and sustainability standards remain at the highest level. “We’re not just talking about wind turbines. We’re talking about revitalizing local economies and protecting the Shore’s way of life.” Union representative Jim Strong echoed that sentiment, noting that Maryland’s labor community sees offshore wind as a chance to rebuild domestic manufacturing capacity while giving workers access to strong wages and long-term stability. Environmental voices, including Jim Brown of the Audubon Society, focused on how properly sited wind projects can reduce carbon emissions while coexisting with marine wildlife and migratory bird patterns. While most of the evening centered on data and community questions, the event briefly turned tense when Ocean City Mayor Rick Meehan, who is leading a lawsuit challenging Maryland’s offshore wind plans, attempted to question the panel. The mayor appeared to lose his train of thought mid-sentence and later cast doubt on the reality of climate change, drawing visible concern from several attendees. Meehan, a New Yorker who moved to Ocean City in 1971 and has held public office since 1985, has become one of the region’s most vocal opponents of offshore wind. His critics argue the lawsuit represents an effort to stall progress rather than engage with the facts presented by energy, labor, and environmental experts. Despite the brief exchange, the overall tone of the evening was forward-looking. Residents lingered after the formal discussion to review informational materials, speak with industry representatives, and learn about opportunities for community involvement. For many, the message was clear: Maryland’s transition to clean energy is not only feasible, it’s already underway, and the Eastern Shore stands to benefit.
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