Bradford Pear tree is a type of Callery Pear (Pyrus calleryana) that was once the official tree of Prince George's County and in the 1960’s became one of the most popular street trees in the country. As detailed in a previous article it was originally developed at USDA to resist fire blight, a bacterial disease that was afflicting US pear trees. The researchers at Glenn Dale tested some of the first cultivars in nearby University Park. Prized by highway departments and suburban developers for its fast growth, profusion of flowers, and tolerance of most soil conditions, it was planted widely as the first and sometimes only flowering tree in new communities. So why are they being removed and outright banned in cities and states across the country?

In addition to their unpleasant odor, a major issue with the Bradford Pear tree is a weak branching structure that leaves them prone to splitting and dropping large branches. As a result, Bradford Pears have a much shorter lifespan than other street trees and makes them extremely hazardous to the communities they grace. Unfortunately, when alternative cultivars with stronger branch structures were developed to remedy this issue, they created an even worse problem. Though the Bradford Pear was designed to be a sterile tree, cross pollination with these new cultivars produced viable seeds that have proliferated in the landscape. Birds eat the fruit and distribute these seeds widely, which spread rapidly to overtake native species and disrupt natural succession. These can occupy the forest edge, choking out native serviceberries, redbud, and dogwood, and also spread into open areas and fields overtaking native grasses, flowers, and shrubs that are vital to Maryland’s native species.

Another issue with these hybrid pears is that they are very difficult to control. Not only do they spread rapidly, the new hybrid seedlings grow in dense thickets and sport large thorns that have been said to puncture tires. Even if you are able to cut them down, they will often resprout vigorously - new suckers can sprout from cut stumps or large roots that are close to the soil surface. As a result, once the wild pears have invaded a natural area, it is very difficult to remove them permanently without damaging the native ecosystem. Because of this the Callery Pears have been deemed invasive species and has resulted in the recommended and systematic removal of Bradford Pear trees from roadsides and city parks in many jurisdictions throughout the eastern United states. Some states have even banned the sale and planting of Callery Pear to limit the spread.