ANNAPOLIS – The white-blossomed story book trees line countless streets in the state – but that is just the problem.
Callery pears, also known as Bradford pears, are commonly used to landscape everything from new developments to malls. But the fast-growing Asian import has some nasty side effects, according to the Invasive Species Council, which named it the April Invader of the Month.
“In trying to fill a gardening niche we created a monster,” said Kerrie L. Kyde, habitat ecologist and invasive plant specialist for Maryland’s Department of Natural Resources. “You see it everywhere; most of what you see that is in bloom right now was not planted.”
Every month the council, part of the Maryland Department of Agriculture, announces a new invasive species of concern. January’s species was the Emerald Ash Borer, which caused the department to cut down a great number of Ash trees in Prince George’s County.
When the Bradford pear was first introduced in the 1960s it was sterile – meaning it produced small fruits that would not pollinate. But the tree has a tendency to split when it reaches maturity because of a bad combination of soft wood and narrow branch angles. Alternative stronger varieties – such as the Cleveland pear – were introduced to combat the problem.
But these new varieties pose a serious unexpected problem. They pollinate with the original sterile Bradford pear and cause it to reproduce on its own. Birds carry the seeds from the fruit to wild areas where the pear tree will grow and choke out native flowers and shrubs where birds and insects live.
“They tried to remedy the problem by producing cultivars that were less prone to splitting. But when they did that they introduced other pollen sources that were compatible. You started getting fruit with a viable seed,” said Kyde.
Kyde does not plan to remove trees from neighborhoods, but says it is her job to remove trees along forests that are hindering the growth of native species.
“We won’t go down a neighborhood street and whack all the pears,” said Kyde. “But if I can convince a few people to go to the garden center and not buy a pear tree and instead buy a shadbush, then I’ve done my job.”
The tree is a natural advertisement for itself in the spring, according to Robert Lee, Manager of Meadow Farms Nursery in Leonardtown. People see the pear trees growing along highways and neighborhood streets in the spring and then purchase them in order to replicate the delicate clustered flowers in their own yard.
“They see it blooming and come in looking for it at a retail business,” said Lee.
Lee carries both Bradford and Cleveland pears at the nursery, and says he prefers the Cleveland pear.
“We had two Bradfords in front of the nursery that split,” said Lee. “I have had to take seven out of my pop’s house. Some people still do not know about the splitting of the Bradford so we keep some in stock.”
The splitting problem has been noticed by Mary Willard of Bel Air, who does not plan to plant another pear tree. The street she lives on in Hampton Ridge is lined with Callery pear trees, which have fallen down often over the past thirteen years. Though she has a pond with giant gold fish, a blackberry bush and various types of trees in her yard, the pear tree in her front yard was the focal point. “The wind blew it down last fall and I almost cried it was so pretty,” said Willard. “We are going to plant a pink dogwood in its place.”