Invasive Species in New Jersey - Series 6 Article 2 - The Ubiquitous ‘Bradford’ Pear

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By Dave Parsons






Pyrus calleryana ‘Bradford’ blossoms in Spring.
E+, River North Photography
www.gettyimages.com

     “Known for its iconic springtime blooms and signature, easy-to-identify silhouette, the Bradford Pear Tree is a symbol of the [Spring] season. Warmer months translate to a blanket of white blooms on each Bradford…blooms that tolerate a variety of hard conditions. In fact, the Bradford thrives through pollution and drought. Hot temperatures are no problem for the Pear Tree, and it’s perfect for lining streets, driveways and beyond because it’s not affected by smog or car exhaust. Even better?  You can plant it in an array of soil types – and it still grows well.”[1]  So reads the description on a website selling one of the most problematic invasives[2] currently available in the marketplace. A more truthful description might read: “For only $60 plus shipping, you too can own one of these eco-unfriendly, ticking time bombs to place in your landscape.”
     Pyrus calleryana is native to China, Taiwan and Vietnam. It’s an attractive ornamental tree that grows in an upright pillar-shape, blooms full of snowy-white flowers early in the growing season, follows with long-lasting glossy, green leaves and ends the season with beautiful fall coloration.  It first arrived on American shores sometime in 1908 when it became part of the collection at Boston’s world-famous Arnold Arboretum.[3]  Seven years later, P. calleryana became a key weapon in the U.S. Department of Agriculture’s (USDA) battle against fire blight that was ravaging the commercial pear crop. In fact, a significant percentage of the surviving common pear trees--Pyrus communis--did so on rootstock from P. calleryana.[4]  Having already exploited its hardiness, the USDA began developing cultivars of P. calleryana at its Plant Introduction Center in Glenn Dale, Maryland. By the early 1960s, the USDA introduced
     P. calleryana ‘Bradford,’ named after F. C. Bradford, former horticulturist-in-charge of the USDA facility in Maryland. ‘Bradford’ was touted for its beauty, hardiness, adaptability and rapid growth rate.[5]  For the next several decades the ‘Bradford’ Pear was a tree of choice for developers, landscapers and even urban planners.

Bradford pear tree in Medford, New Jersey which split under its own mass.

Photo by author.


     Sometime in the 1980s, the Bradford Pear began to gain a reputation as being excessively susceptible to structural failure. At fault is the tree’s morphology--all major limbs diverge from a single point on the trunk. This makes it particularly vulnerable to wind, snow and ice damage.  All too frequently, mature ‘Bradford’ pears will split or collapse under their own mass. Municipalities around the country have discouraged or outright banned plantings of ‘Bradfords’ because of their tendency to drop branches onto sidewalks or power lines and the potential risks to passersby.[i]  Some communities have taken the drastic step of creating exchange programs that provide a free replacement tree (of another species) for every ‘Bradford’ pear homeowners remove from their property.[ii]  In response to the growing disen-chantment with the ‘Bradford’ pear growers and nurseries began offering other cultivars of Pyrus calleryana. This seemingly innocuous response to regain lost market share would lead to the ecological nightmare that ‘Bradford’ has become.

Roadside stand of ‘Bradford’ pear.  Note early bloom compared to native trees.

Britt Slattery, US Fish and Wildlife Service
www.bugwood.org


     Original specimens of Pyrus calleryana ‘Bradford’ introduced to the American marketplace were in fact sterile. The trees could not self-pollinate, nor could two samples of the same variety fertilize each other. Now enter the many new cultivars intended to replace weak ‘Bradford’ trees. Already existing plantings of Pyrus calleryana ‘Bradford’ were able to be pollinated by these new cultivars and the resultant offspring are fully fertile.[1]  Combine a newfound fecundity with the circumstance that the previously sterile fruit of ‘Bradford’ pear tress had become a favorite food source for birds and small animals and the previously innocuous ornamental quickly became a threat to native tree species.  “Once established Callery pear forms dense thickets that push out other plants including native species that can’t tolerate the deep shade or compete…for water, soil and space.”[2] 

     Once the darling of the landscape industry, P. calleryana ‘Bradford’ is—rightly so—looked upon with enmity by naturalists. Unfortunately, the ‘Bradford’ pear will likely be with us for the foreseeable future. Removal of established stands of the “wild” Bradford pear trees is estimated to cost several thousands of dollars per acre.[3]  Responsible gardeners should heed the caution of organizations like the South Carolina Forestry Commission: “Do not plant Callery or Bradford pear. Instead, plant native alternatives, such as serviceberry, fringe tree, tupelo, or dogwood, among many others.”[4]

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[1] https://www.fast-growing-trees.com/products/bradford-pear-tree  Accessed 22 May 2019.

[1] In this series of articles the informal term “invasive(s)” is used to refer to any invasive species.
[1] Theresa Sculley, “The Rise and Fall of the Ornamental Callery Pear Tree.” Arnoldia (February 2017), 4.
[1] Jil Swearingen et al., Plant Invaders of Mid-Atlantic Natural Areas, (National Park Service and U.S. Fish and Wildlife Service, Washington DC, 2010), 80.
[1] https://www.nytimes.com/1964/01/05/archives/bradford-pear-has-many-assets-new-ornamental-fruit-offers-sturdy.html Accessed 30 May 2019.
[1] https://www.nytimes.com/2016/03/19/opinion/the-ups-and-downs-of-the-bradford-pear.html?register=email&auth=register-email Accessed 30 May 2019.
[1] https://www.southernliving.com/garden/grumpy-gardener/bradford-pear-trees-fayetteville-arkansas Accessed 22 May 2019.
[1] https://www.southernliving.com/garden/grumpy-gardener/i-just-hate-bradford-pear  Accessed 22 May 2019.
[1] Swearingen, 81.
[1] https://www.firstcoastnews.com/article/news/the-curse-of-the-bradford-pear/110265126  Accessed 22 May 2019.
[1]http://trees.sc.gov/pubs/bradfordpear.pdf  Accessed 22 May 2019.





























[2] In this series of articles the informal term “invasive(s)” is used to refer to any invasive species.
[3] Theresa Sculley, “The Rise and Fall of the Ornamental Callery Pear Tree.” Arnoldia (February 2017), 4.
[4] Jil Swearingen et al., Plant Invaders of Mid-Atlantic Natural Areas, (National Park Service and U.S. Fish and Wildlife Service, Washington DC, 2010), 80.
[9] Swearingen, 81.

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