What’s in a name?
By Kim Bagby, VCE Master Gardener, Virginia Master Naturalist Those pretty white trees, so familiar in early spring. They blossom before they leaf out and give us a glimpse of summer’s promise. Most everyone I know calls them Bradford pears. Some people hate them, some love them, and all of us are stuck with them, at least for now. As an invasive non-native tree, it’s fouling our environment in more ways than we can count, but let’s face it: we’re not going to be able to completely eradicate the non-natives. The best we can do is damage control. That’s why, in some circles at least, we’re seeing a lot about how to deal with Bradford pears this spring. There are certainly plenty of experts willing to tell you how to do that, and we’ll leave them to it. There’s a pretty interesting story, however, in how we got here in the first place. There are at least two sides to the story. The first one begins over a century ago in China. Fire blight was running amok in the lush apple and pear orchards of the Pacific Northwest. Frank Reimer with the Southern Oregon Experiment Station was looking for a fix. Fire blight is caused by the bacterium Erwinia amylovora and this was about a quarter of a century before the discovery of penicillin, let alone the streptomycin and oxytetracycline that would start being used against the disease in the 1950s, so he had to find another option. He was looking for a variety of tree resistant to fire blight that he could cross with our own native stock to strengthen the orchards’ resistance to the devastating disease. By 1915 Reimer had identified a Chinese pear, Pyrus calleryana, the Callery pear, as being the variety he sought, and urgently requested the Department of Agriculture to send someone over to collect the hundreds of pounds of seeds and roots that would be needed to develop a pear that would save the orchards. Long story short, it worked. A resistant variety was successfully developed and put to work. It was even resistant to pests. Hurrah! But the second part of the story is the one that concerns us today. In the 1960s, the Department of Agriculture released Callery pears, particularly the cultivated variety (“cultivar”, for short) “Bradford” for use as an ornamental tree. The Bradford is beautiful, fast-growing, and tolerant of a lot of different soils, nutrients, moisture, and light levels. It was sterile, meaning it couldn’t self-pollinate so it wouldn’t reproduce where it wasn’t wanted. What’s not to like? A few things, it appears. As use of the trees spread, they also became known for the stench of their flowers. Their rapid growth can lead to limb loss from instability, and storms can easily damage them and whatever property of yours they land on. Rapid growth generally means short-lived. Their main pollinators are flies, not bees. And it turns out there’s a way around that pesky sterility idea. There are different cultivars of the Callery pear in addition to the Bradford. Varieties such as 'Aristocrat', 'Autumn Blaze', 'Capital', 'Chanticleer, 'New Bradford', 'Redspire', 'Whitehouse'—these varieties were developed to fine-tune desirable qualities or downplay the negatives, or some mix of both. These cultivars may be sterile within their own variety, but they can cross-breed with others. I say they “may be” sterile within their own variety, but the trees that have cross-bred can and do cross-breed again, and again, and again. By the 1990s, if not earlier, it was obvious that the Callery pears had escaped cultivation and were now growing wild. Within twenty years or so they had been found in habitats ranging from wetlands to forests, crowding out valuable natives that better supported local pollinators. As with everything else we plant in our gardens, their seeds go wherever the herbivores that eat the plants or their fruit go. And so they spread. The offspring trees now have a crazy quilt of genetic backgrounds and interbreed readily, resulting in more viable seed, more expansion, and more dispersal of the species. You generally see them at the edges of the forest and in open fields where they can enjoy full sun, sometimes in dense thickets. The fruit varies from the marble-sized balls of the original Bradford that softened after the first frost, to rock-hard, tasteless, fist-sized pear-shaped, well, pears. Some varieties have wicked thorns. Most of them do have nice fall color if we don’t get an early hard freeze. The offspring have probably drifted so far genetically from the Bradford cultivar that it’s not accurate to call them Bradfords anymore. But when someone says “Bradford pear”, we pretty well know what they’re talking about whether it’s actually a Bradford or some distant cousin. To try to limit the damage, Ohio and South Carolina are banning the sale of Callery pear trees. Certain other states or areas are offering bounties for every Callery taken down, usually in the form of a free native tree to plant instead. And the fire blight? It turns out that the trees weren’t the only ones evolving genetically. So was E. amylovora. Ornamental pears are increasingly at risk from the very bacterium they were developed to evade. Ah, the circle of life. This is a complex subject and I read a lot of references. Any errors are my own. Much more information is available online or in our local libraries. Some interesting links are posted at the Southside Master Gardeners website, SSMGA.org. As always, I’m thankful for the Southside Master Gardeners and Southern Piedmont Master Naturalists, from whom I’ve learned so much. The Virginia Cooperative Extension Halifax Extension Office is open from 8 a.m. to 5 p.m. Monday-Friday. If you have gardening questions, you can continue to reach an extension master gardener or extension staff member by sending an email to email@example.com or calling the Halifax Extension Master Gardener Help Desk at 434-830-3383. Be sure to give us your first and last name, telephone number and the nature of the call. The help desk phone is routinely checked Monday-Friday. Someone will get back to you, although it may be from a different telephone number.