Callery pear trees’ spring blossoms represent biodiversity loss in Virginia ecosystems
Each spring, roadsides across the commonwealth are blanketed by white blossoms as wild Callery pear trees bloom. Though these conspicuous, early-blooming trees might look beautiful from your car window, Callery pear trees pose a threat to urban and suburban environments, home landscapes, and wild areas throughout the southeast.
Popular cultivars of the Callery pear, such as the ‘Bradford’ pear, have been widely used as ornamental landscape trees since the 1970s. While Bradford pears were initially seen as cost-effective, fast-growing, and easy-to-establish additions to the suburban landscape, their structural weakness as mature trees and the ease with which their seedlings spread present several problems.
“Bradford pears are beautiful as young trees, but as they mature, you will eventually experience losses when you install them in your landscape,” said Eric Wiseman, associate professor of urban forestry and arboriculture and a Virginia Cooperative Extension specialist in the College of Natural Resources and Environment. “The Bradford cultivar of Callery pear is particularly susceptible to branch and stem failure due to bark inclusion.
“The trees grow very fast and tend to have very upright branches growing close together. Often, these branches will grow into one another, trapping bark in between them, which creates an 'inclusion' that causes friction and can cause the tree to split, potentially causing damage to the landscape or nearby structures,” Wiseman said.
Callery pears also pose serious environmental concerns.
Ornamental plantings of Bradford pear often produce fertile seeds that are readily spread by birds. These wild-growing seedlings inherit the genetics of their uncultivated ancestors, which means they can develop undesirable characteristics, notably sharp thorns, that are not seen in cultivated varieties of Callery pear. Since Callery pear trees are tolerant of harsh growing conditions and thrive even in poor soil, these seedlings establish easily in disturbed areas, such as roadsides.
“In areas without active vegetation control, such as roadsides and road interchanges, you see a proliferation of Callery pear. There are some areas along roads that are now 100 percent Callery pear trees,” Wiseman said.
“They’re also very hard to control. If you cut the stem back at ground level, it will still grow from the root, so all you’ve done is cut the plant back, not kill it,” he added.
“In the Northern Shenandoah Valley, we have seen Callery pear overtake fallow fields,” said Mark Sutphin, Virginia Cooperative Extension agent in Frederick County. “Then when people go to reclaim their field, they have a really difficult time. The seedlings can have significant thorns, almost like a honey locust, that makes them very hard to remove. The thorns will even pop tires.”
“Though places in Northern Virginia have been dealing with this issue for a long time, it’s only within the last 10 years that we’ve started to see Callery pear become a real problem in the Northern Shenandoah Valley,” he said.
The Callery pear’s spread throughout the commonwealth represents the shrinking biodiversity of Virginia’s urban forests.
“More resilient forests are less susceptible to problems with disease and insect pests we’ve seen in the last decades,” Wiseman said. “The Callery pear is not a good tree to have in the urban environment.”
There are alternatives to invasive Bradford and Callery pear cultivars.
Wiseman emphasizes that “nonnative” does not necessarily mean “invasive,” and some “nonnative” tree species make fine replacements, though he does recommend planting native species when possible.
A few native alternatives to Bradford or other Callery pear cultivars:
- Flowering dogwood, Cornus florida
- Serviceberry, Amelanchier spp.
- Green hawthorn, Crataegus viridis
- Chokecherry, Prunus virginiana
- White fringe tree, Chionanthus virginicus
A few nonnative alternatives to Bradford or other Callery pear cultivars:
- Japanese tree lilac, Syringa reticulata
- Crepe-myrtle, Lagerstroemia indica
- Tatarian maple, Acer tataricum
- Amur maackia, Maackia amurensis
- Adirondack crabapple, Malus ‘Adirondack’
For more information on woody plants in the landscape, check our Virginia Cooperative Extension publication: Selecting Plants for Virginia Landscapes: Showy Flowering Shrubs.
Interested in learning more about gardening? Virginia Cooperative Extension Master Gardeners can help! Master Gardeners bring the resources of Virginia’s land-grant universities – Virginia Tech and Virginia State University – to the people of the commonwealth. Contact your local Master Gardeners through your Extension office or click here to learn more about gardening in Virginia and the Virginia Extension Master Gardener program.
- Written by Devon Johnson