One sign of spring are the white blossoms of Bradford pear trees. This oval-shaped oriental became a favorite of landscapers and was widely planted in yards, city malls, business campuses, parks and downtown revitalization efforts from the 1960s up to 2000, but after four decades the Bradford pear would appear on the categorized lists of invasive trees in nearly all the eastern, midwestern and southern states.
In the early 1900s, United States pear orchards were in danger of being wiped out by fire blight disease. The U.S. Department of Agriculture sent Frank Meyer, a scientist, to China to search for a disease resistant fruit variety. Meyer collected several hundred pounds of the Chinese Callery pear seeds. He headed to Shanghai on a riverboat in 1918. The boat arrived with the seeds but Meyer was missing. His body was later found in the river, the cause was never determined.
Meyer’s Callery pear seeds were shipped to the USDA Plant Station in Glen Dale, Maryland. Over the next three decades plant scientists found that the Callery pear was fire blight resistant but it did not produce edible fruit. Although it had little value for orchard growers, the Glen Dale station chief, Charles Bradford, thought the Callery pear might make a good oriental tree. He was working on its development when he collapsed of a heart attack in 1951.
Frank L. Creech continued Bradford’s work. He found one variety of the Callery pear tree had a pleasing shape and produced a proliferation of white flowers. Creech reproduced the tree and eight years later the carefully pruned test trees were deemed a success. Creech named the tree Bradford pear in honor of his deceased boss.
By 1962, the Bradford pear was available commercially and became one of the most widely planted ornamental trees in the United States. All ornamental pears originate from Pyrus calleryana, commonly referred to as Bradford pear.
The trees were very popular because of their prolific spring flowers, dark glossy leaves and ability to thrive in almost any kind of soil - and because as a hybrid, people thought they were sterile, therefore having no messy fruits to contend with. The tree grew only 20-25 feet tall, retained its oval shape and in the fall, leaves had brilliant colors.
In 1966, Lady Bird Johnson planted a Bradford pear in Washington, DC publicizing its use as a landscape tree.
Fast forward to the 21st century when conservationists and forestry scientists were calling the Bradford pear an “invasive tree”. By 2011, at least 26 states had reported problems with the spread of wild Callery (Bradford) pear.
In 2007, Theresa Cully, an Ohio scientist, documented the reason for the spread of wild Callery pears. As other cultivars were developed and released, each cultivar was genetically different from the others which meant they could, and did, cross with each other producing lots of fruit and seedlings trees. Birds ate the fruit and scattered the seeds across the landscape. The proliferation of wild Callery pear thickets has been wide spread, most noticeably around municipalities and non-cultivated areas. Its invasive spread has been largely uncontrolled. Callery pear populations have exploded and threatened native biodiversity as the trees steadily march into our native grasslands and forested areas, even becoming a headache for land developers.
Callery pear (Bradford pear) continues to be one of the most invasive tree species in our area.
To learn more about native trees good for landscaping visit the MDC website at https://mdc.mo.gov/trees-plants/treecare.
A lawn is nature under totalitarian rule. -Michael Pollan
