Callery pear (Pyrus calleryana), better known as ‘Bradford’ pear, has been blooming across Illinois. Over the years, it has been a popular tree to plant, especially in residential areas. Trees will reach 30 to 40 feet in height and produce numerous white flowers in the spring. Trees also have attractive glossy leaves that will turn a brilliant red-orange in the fall. However, they are also becoming increasingly problematic across Illinois and the United States.

How did Callery Pear get here?

Callery pear has been imported to the U.S. multiple times. It was originally imported from Asia in 1909 to the Arnold Arboretum (Harvard University) and again in 1916 by the U.S. Department of Agriculture for the development of fire blight resistance in the common pear (Pyrus communis), which was a serious problem in the commercial pear industry at that time.

Callery pear was used as a rootstock for edible pears before gaining interest as an ornamental plant. In the 1950s, the ornamental value and hardiness of Callery pears were recognized, leading to the development of several cultivars, including the most well-known ‘Bradford’. By the 1980s, Bradford pear had become the second most popular tree in the U.S.

It has been widely planted due to its quick growth, adaptability to a wide range of soils, and pollution and drought tolerance. The trees also have a symmetrical to round shape that many people find desirable in addition to their abundant spring floral display. 

The problem(s) with Callery pear

Unfortunately, Callery pear has several negatives. They have narrow branch angles, and this, along with their rapid growth, makes them rather weak. Trees often split and break apart during storms and frequently don’t last longer than 20 years before they begin to split apart. Additionally, while the floral display may be impressive, the smell is not. The fragrance of Callery pears has been described as smelling like dead fish, vomit, urine, and other undesirable things.

When ‘Bradford’ pears were originally introduced to the landscape trade, they were touted as having sterile fruit. This is because they are self-incompatible, meaning they require cross-pollination from another cultivar to produce seeds. Since most of the Callery pear trees that were originally planted were ‘Bradford,’ there was very little pollination occurring (unless they were planted near another cultivar).

However, new cultivars have been introduced, such as ‘Cleveland Select,’ ‘Aristocrat,’ and ‘Redspire.’ The introduction of these new cultivars meant greater chances for cross-pollination and, therefore, seed production. 

Now that several cultivars are being grown in landscapes and trees have been able to produce viable seeds, Callery pear has escaped into the environment. Birds and other wildlife will consume the fruits from trees and disperse them. Callery pear is now showing up in disturbed areas, as well as natural areas. Driving along highways and interstates, you can often see thickets of Callery pears in fields along the roadside (along with bush honeysuckle). Callery pears can quickly become established in an area due to their rapid growth as well as their ability to produce large amounts of seed. Once they become established, Callery pears can form dense thickets that push out native species that cannot compete with them.