Jennifer Behnken, Urban and Community Forestry Coordinator
Southern Illinois University Carbondale, Dept. of Forestry
Agriculture Building - Mailcode 4411
1205 Lincoln Drive
Carbondale, IL 62901
Bradford Pear: A Blessing or Bad Fortune?
We've all seen them. Driving down roadways, we awe at the rows of trees with beautiful white blossoms, usually some of the first to bloom with the arrival of spring. Their pyramidal shape gives way to an oval form as they mature, lending a manicured appearance. They bring a sense of excitement that nature is once again waking from its slumber in the spring while giving us a bright farewell in the fall with an array of scarlet, purple, and gold foliage. Have you guessed what tree species this is? Yes, it is the bradford pear tree.
Its origins are from the callery pear, Pyrus calleryana, brought over from China, Korea, and Taiwan regions. It was imported to the United States to provide resistance to the fire blight disease, although unsuccessfully. To this day, fire blight is a common problem for pear trees. Bradford pear is the original cultivar from callery pear and remains the most widely known. It was praised for its aesthetic appeal, low maintenance, and resistance to extreme environmental conditions, such as drought, soil compaction, and pollution in urban settings. Its popularity encouraged the development of several other cultivars, including the Aristocrat, Cleveland, Chanticleer, and Redspire. Several years ago, I bought a house with four of these trees bordering my driveway and, like many others, enjoyed the beautiful early blooms and late leaf drop. It is a universal landscape tree and to this day, remains frequently planted.
Still don't know what tree I'm referring to? Here are some tips of how to identify this species. In the spring, they burst forth with white blossoms, the flowers in abundant five-petaled white clusters. Their main branches extend outward from one focal point on the trunk, giving it a shape of a popsicle or a lollipop. Their leaves are alternately spaced and comparable in shape to many fruit trees with a glossy oval shape, up to three inches in length. The bark is gray-brown and smooth on young trees, splitting into small scales as they mature. Even though Bradford pear trees were bred to be sterile, they still produce small, hard fruits that look like tiny hard apples with the texture of an undeveloped pear fruit.
Despite its popularity, the Bradford pear and its many cultivar cousins exhibit several problems. Its lack of a central leader and branching habit leads to weak structural supports. Combined with its brittle wood, the main branches have a tendency to split during wind and ice storms, leaving ugly wounds or decimating the tree all together. Since this tree is commonly planted along streets and sidewalks, their splitting habits can be a hazard to vehicles parked along the road and to pedestrians on sidewalks. They are also a short-lived tree with a life span of merely 20 years on average. This lack of longevity leads to frequent need for replacement and puts a strain on city tree management budgets. They also require aggressive pruning to combat poor branch development and can mean more maintenance than originally anticipated.
Recently, the biggest area of concern is its escape to the wild, becoming an invasive species and an ecological challenge. Their popularity has led to overplanting in communities, setting the stage for possible invasion. Although each cultivar was bred to be sterile, when new varieties were introduced, cross pollination occurred, leading to fruit fertility. Combined with birds eating the fruits and dispersing the seeds and propagation by root sprouts, the once beautiful, genetically sterile pear has evolved into a hybrid of its callery pear parent, complete with thorns. These accidental hybrids produce dense infestations of trees in fallow fields, right-of-ways, under utility lines, and other natural open areas. They pose a threat to native vegetation by displacing native plant communities. Left unchecked, they become susceptible to toppling. The larger they become, the more costly it is to remove these fast growing trees.
|Escaped callery pear trees. Photo by|
Jim Miller, invasive.org
What can we do about it? The solution resonates within our personal choices. While it is impractical to replace all callery pear cultivars, we can consider alternative replacement choices as existing callery pear cultivars become unhealthy and need to be removed. There are several native and non-invasive options that would provide the similar tree characteristics, such as easy maintenance, small stature, or beautiful spring blossoms. The Columbia Parks and Recreation in Missouri has launched a Stop the Spread campaign to promote community awareness of this potential threat and provide more ecologically friendly recommendations of alternative plantings (see link HERE) .
Several organizations in the Carbondale area have decided join forces and establish a native tree demonstration plot to display callery pear alternatives. Please stay tuned to see how you can participate this spring in this developing venture!
Any questions or comments, please feel free to contact Jennifer Behnken, Southern Illinois University Community and Urban Forestry Coordinator at 618-453-2517 or at firstname.lastname@example.org.