What to Do About Fire Blight on Bradford Pear Trees

A Bacterial Disease That Attacks the Rose Family

Image: proof that 2 plants can be the same type, growing next to each other, yet be different.
Bradford pear trees have masses of white flowers in spring and nice fall foliage. However, they have weak limbs and, although resistant to it, sometimes succumb to fire blight. David Beaulieu

What does one do to treat "fire blight" on Bradford pear trees? And what exactly is this horrible-sounding problem? No good can come, surely, from a condition that unites those two ominous words, given the destructive power of fire and the downcast mood evoked by "blight" (which, in the general sense, is defined as any cause of impairment, destruction, ruin, or frustration).

A reader wrote in to inquire about just this problem. "The flowers on my Bradford pear trees turned black this year, and the new growth has died," he scribed. "The ends of the limbs are dead. What is wrong? Is this some sort of disease? And if so, how should I treat it?"

What Is Fire Blight, Exactly?

The symptoms that the reader reports indicate fire blight. Before you learn what to do about it, let's explore precisely what it is.

Fire blight (sometimes spelled as one word) is a bacterial disease. The type of bacterium that causes it has the Latin name of Erwinia amylovora. The disease attacks trees and bushes in the rose family. If you have not been introduced to the rose family, please note that this designation does not refer simply to the fragrant rose bushes with which you have probably been familiar since childhood. Both apple trees and pear trees belong to this plant family, for example. 

Not only do the pear trees grown for their edible fruit succumb to fire blight, but also ornamental types such as 'Aristocrat' pear trees. While Bradford pear trees are relatively resistant to fire blight, that does not mean that they are totally immune to it (especially in warmer climates). Blackened flowers are an indication of fire blight. Fire blight bacteria can move down a branch and form a canker; it can eventually kill the branch or even the entire specimen. Remember that, since bacteria is at the root of the problem, treatment with a fungicide will have no effect on fire blight.

What to Do About Fire Blight on Bradford Pear Trees

Taking care of fire blight DIY-style is somewhat problematic, according to the University of California. They write, “Copper products are the only materials available to homeowners for fire blight control, and they often don’t provide adequate control even with multiple applications.” They suggest that some good can be done by a weak “Bordeaux mixture or other copper product applied several times as blossoms open,” but they go on to say that this will not solve your fire blight problem entirely.

Have an arborist look at your Bradford pear tree if it is infested with fire blight. The disease can be treated if it is caught in time. An arborist will locate, prune off and dispose of the affected branches to stop the spread of the bacteria. As professionals, arborists also have access to sprays to which the average homeowner would not have access. An arborist may elect to use a bactericide (with streptomycin sulfate) on your Bradford pear tree to control fire blight.