This time of year the Bradford Pears look so pretty, though they also remind me of what an invasive pest they have become. Just drive along the highways during the early spring and you can easily spot where they are taking over.
Ornamental pears were introduced to the United States in the early 1960s and came from China. All ornamental pears originate from Pyrus calleryana, or callery pear, commonly referred to as Bradford Pear. Ornamental pears were originally very popular trees due to their prolific spring flowers, dark glossy leaves and ability to thrive in almost any kind of soil—and because people thought they were sterile and therefore had no messy fruits to contend with.
The first major downfall of ornamental pears came 15–20 years after the initial trees were planted. At that point, many unsuspecting homeowners found out that the branches and trunks of pears split in storms. Also, ornamental pears are more susceptible to a fungal disease called fire blight than was hoped when they were first introduced.
However, it has not been until the last few years that people have been noticing the ornamental pears we thought could not spread … are. And, they are doing so quite prolifically. In fact, 26 states have reported wild callery pears spreading in the past decade. How could this have happened?
There are two causes. One is due to the fact that ornamental pears have been overplanted in our communities. Although each different kind of callery pear cannot reproduce by itself, it turns out that when these many types of pear are all planted close together (like they are in our towns) they can crosspollinate and produce fruits. The other method of ornamental pears reproducing is if the sprouts that sometimes grow from the base of pears are not pruned they can flower and crossbreed with the flowers of the tree itself. These small fruits are eaten by birds and are then scattered along fences and roadways, pastures, abandoned fields, natural areas and under power lines. Wild trees then sprout from these fruits and begin reproducing quite quickly. In fact, wild callery pear trees start producing flowers and spreading themselves after just three years.
What can homeowners and landowners do to help? Consider diversifying the next time you plant a tree and avoiding ornamental pears or any other non-native trees with invasive tendencies. Secondly, prune off any sprouts that grow from the base of your ornamental pears to prevent crossbreeding with the sprouts and tree itself. Lastly, if you have ornamental pears consider replacing them with a different kind of tree once the pears decline or are damaged.If you spot wild callery pears on your property, control them by cutting them down and immediately treating the stumps with appropriate systemic herbicide to prevent them from re-sprouting.
Information from Missouri Department of Conservation