Every spring, all over in South Carolina, we see yards, abandoned lots, natural areas, roadsides, and, in some cases, forests filled with white flowers. These first white flowers of the year are nearly all from the Callery pear tree (Pyrus calleryana). This tree is native to China, and while they may look the same, many of the trees planted in yards, around businesses, and in other managed landscapes across South Carolina are cultivars of P. calleryana. One of the most common cultivars is the Bradford pear, for more information on Bradford pears see HGIC 1006 Bradford Pear). Bradford pears, by themselves, cannot produce viable seed. But, if pollen from a different flowering pear cultivar (or a wild Callery pear) pollinates a Bradford pear flower, then viable seed can be produced. The fruit is often eaten by birds, and birds doing what birds do (hint: they poop), spread the seeds across the land. When these new plants grow, they’re now Callery pears, the wild relative of Bradford and other cultivated varieties of Pyrus calleryana.
Callery pears are an aggressive invasive species. The stems and branches possess thorns (sometimes up to 3” long!), they can spread by seed or through root sprouts, and they can quickly take over a roadside, old field, pasture, vacant lot, or forest understory. Once established, they’re difficult to remove because of the thorns, which can easily puncture the skin, wound livestock, or pop tires on vehicles or implements. Prescribed fire is not a good way to clear the land of them, because research has shown that for every stem that fire kills, four more will resprout in its place. Many herbicides, including glyphosate and triclopyr, are effective in killing Callery pear, and at this time, this is the best way to remove this plant.
Did you know some songbirds require thousands of caterpillars just to raise a single clutch of eggs to adult birds? And, nearly no insects (especially caterpillars) feed on Callery pear (or any of the P. calleryana selections, including Bradford pear), which means every one of these trees represents a “food desert” to birds.
Callery pears represent one of the most aggressive invasive plants we have in South Carolina, and a big part of why they’re a problem is because they can come, in part, from Bradford and other fertile Callery pear cultivars. Bradford pears are planted in many yards across the state and serve as pollen donors or recipients for Callery pears. Removing Bradford pears is one action landowners can take to help stop the spread of Callery pears.
The Bradford Pear Bounty Program, sponsored by Clemson Extension, the City of Clemson and the South Carolina Forestry Commission, is giving free native replacement trees to Clemson area residents if they remove their Bradford pear tree. Information about the program is available at https://www.clemson.edu/extension/bradford-pear/.