Callery Pear

The Callery Pear (Pyrsu calleryana) is an ornamental tree. Whilst the term 'Bradford pear' is sometimes used to refer to the whole species, the Bradford pear is technically a specific and popular cultivar of this species.

Native Range
The Callery pear is native China (presumably towards the south-east) and Vietnam.[1]/[2]

North America
The Callery pear has become established in a large portion of eastern United States. It is present in New York's Long Island, New Jersey, Delaware, south-east Pennsylvania, Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida (especially the panhandle), Alabama, Tennessee, Kentucky, West Virginia, Ohio, Michigan, Illinois, Montana, Arkansas, Louisiana, east Texas, Oklahoma and east Kansas. Elsewhere in the United States of America the Callery pear is present in Utah and California.[2]/[3]

Pathways and Introduction
The Callery pear is planted commonly as an ornamental tree and as rootstock for its close relatives, such as the common pear, Pyrus communis).[1]

This species was first introduced to the Unites States in 1909 by the Arnold Arboretum, More specimens were introduced in 1916 by the US Department of Agriculture to help the Common Pear develop a resistance to fire blight, a tree disease which was ruining the commercial pear industry, and was used as a rootstock for that species until around 1950, after which it has become a popular ornamental species used commonly by regional councils.[1]/[4]

The popular Bradford pear cultivar was developed in 1960 by the US Department of Agriculture.[4]

Whilst many cultivars of the Callery pear can not be pollinated by other trees of the same cultivar, every cultivar of this species can cross-pollinate with other cultivars to form hybrid, fertile fruit and seeds. Rootstock may also dominate the tree trying to be bred, resulting in fertile fruit of the rootstock's variety.[1]/[3]

Impacts
Callary pears grow in thick patches, shading out, crowding out and generally out-competing native plant species.[1]/[4]

Due to their fast growth, weak wood and lack of adaptation to the American weather, these trees are more liable to toppling in strong winds than native species, making them a threat to power lines and transportation services (since they block tracks and roads).[4]

Control and Removal Methods
Planting of Callery pear trees is now strongly discouraged, with several native alternatives used ornamentally instead.[4]

Seedlings can be pulled from moist soil whilst medium and large trees should be felled, with the stumps treated with a systemic glyphosate or triclopyr-based herbicide.[1]