TheMondayGarden.com

HOW IT ALL GOT STARTED: It started out simple. Just after the turn of the century, the dou li, called by the Westerners "Callery pear" or "Pyrus calleryana", a lovely rose-family native from Korea and China, was imported into the Western hemisphere – reports put in it Maryland sometime between 1910 and 1920. The original off-spring were sterile. At the time, this alien, like the forsythia, was just another pretty face taking up garden space but not otherwise doing much of anything. In those days, before the sub/urban sprawl had covered much of the land, it was OK to allot garden space to nonproductive foreign plants, because the wild critters could find plenty to eat on “undeveloped” land and weren’t dependent on what could be found in the alleys and backyards. Further, there was plenty of wild land where even the most delicate of our native flora still grew undisturbed.

Post-World War II, hybridizers were trying to create a commercial “eating pear” tree that was resistant to fire blight. Fire blight is one of the farmer’s worse nightmares. It shows up first in the blossoms: they look water-soaked, then turn dark brown and drop. The disease, caused by a bacteria, spreads down the branches and into the trunk, leaving the tree looking fire-scorched. Years of effort to plant and nurture an orchid can be set back a decade in a few weeks. The only real “cure” is to select fire-blight resistant trees and to keep them very, very healthy.

PICTURES: Callery pear cultivar flowers are so lovely in the spring -- white and delicate as wedding lace. Summer Street at Ridgeway Shopping Center, Stamford CT, April 2005; a fall re-bloomer near the Mill River, September 2005.

It was noticed that the Callery pear was highly resistant to fire blight. Legend has it that, around 1950, the Agriculture Research Service in Glenn Dale, Maryland, tried to hybridize the Callery pear into a fire-blight resistant eating pear. The experiment didn’t work but they did come up with an ornamental Callery cultivar called the "Bradford Pear" (Pyrus calleryana 'Bradford'). The story is that, in 1963, the USA Department of Agricultural introduced the Bradford pear commercially. The introduction succeeded and the Bradford became wildly popular; that was the trouble.

PICTURE: Even the winter leaves are lovely, Ridgeway Shopping Center, Stamford CT, Winter 2004

PICTURE: Love, soft green of the new spring leaves Callery pear cultivar, corner of Strawberry Hill and Hoyt Street Alley, Stamford CT, May 2005

THE BRADFORD PEAR: Horticulturally, the Bradford pear was an economic boost to the plant nursery trade: a great small, fast growing tree with a lovely "lollipop" shape, beautiful spring flowers, glossy-green summer leaves, and fantastic late fall color; easy to grow in Zone 5 to 8; needs full sun but tolerant of most soil conditions, pests, urban pollution, and drought. Some thought that the flowers had a bad odor but a small price to pay, right?

The Bradford pear itself was environmentally innocuous for the most part. It was sterile and could not spread. Environmentally, the only real issue was the tendency to over-plant, thus bringing into play the problems caused by monocultures.

The problem with newly introduced trees is just that -- they are new. There's no way to know how a tree's going to perform down the road without waiting decades, and that is not going to happen in a commercially-driven society. It is sort of like what happens with the drugs and pesticides -- the pre-introduction testing is short-term and the problems surface 10 years later.

PICTURE: Callery pear cultivar, corner of Strawberry Hill and Hoyt Street Alley, detail of a similar tree; similar tree on Hoyt Street Stamford CT, November 2004-2005. Note pruning on the latter tree to try to compensate for the branch structure.

THE BRADFORD PEAR FALLS DOWN: What happened with the Bradfords is that they got too big and too old, too quickly. The horticultural “down fall”, literally, is the weak branching structure. If you take a look, you'll see that the Callery pears have a whole bunch of major branches clustered close together and sloping up a very shape angle. The arborists will tell you that, structurally, this doesn't work. Sooner or later, snow, ice, wind, cats, kids or whatever, put a downward force on the branch. As the tree ages, the branch's own weight pulls it down. If the angle is too high, the tree can't use the trunk wood under the branch as a buttress. Instead, the branch splits from the trunk in a long, deep wound, very likely to be fatal to the tree. The fast growing nature of the tree makes the wood softer and more brittle, leaving no way for the tree to compensate for the poor branching structure.

As a result, the Bradfords get too heavily branched and simply fall apart at a shockingly young age for a tree. They tend to only live about two decades, some times less. Good pruning through out the tree's life can help but it is a losing battle. Worse yet, it is one thing for a 10-footer to topple in the yard but these guys get to be 30 to 50 feet, and that's an expensive crash.

Then the horticulturists started to say that Bradfords "might not be the best choice due to a tendency to drop branches". John Shelley, of John Shelley's Garden Center & Nursery in Felton, PA , who "calls 'em as he sees 'em", translates this in to "The Worst Tree Sold In America --The Bradford Pear Is Pure Junk." (In our personal politics, Mr. Shelley is so far to the right, and I’m so far to left, that neither of us could get air time on talk show radio. Accordingly, when we agree something, it is best to listen.)

Trouble is the Bradfords were selling like crazy and it's a fact of American horticultural economics that neophyte home owners buy what they see in the neighbors' yards. Then the push was on to re-invent the re-invented Callery with a better branching structure. Several new cultivars were developed, some of which are supposed to have somewhat less of a branch-drop problem.

PICTURE: Callery pear cultivar broken apart. Homer Lee Wise Memorial Grove, Bedford Street, Stamford CT, October 2005 View close up detail.

NEW CULTIVARS ARE INVASIVE: Now, here the rub: Many of the new cultivars are not sterile!!! They produce small fruits that are gratefully munched up by the squirrels and birds, who excrete the seeds elsewhere and guess what we're getting? You got it: more Callery trees.

One of the best horticultural sites on the web, Floridata , says their wonderfully understated way: "Callery pear has escaped cultivation in parts of the South, including Panhandle Florida, and seedlings sometimes form dense monocultures that exclude native species." The National Park Service and U.S. Fish & Wildlife Service in its guide Plant Invaders of Mid-Atlantic Natural Areas puts it this way: "Bradford pear has escaped plantings and is invading natural habitats in the eastern United States....Do not plant." That's clear, isn't it? And don't think that this is just a southern problem, the Callery children are popping up around town in Stamford, CT (Zone 6).

PICTURES: Hungry squirrels thieving winter buds from a Callery pear cultivar in Hoyt Street Alley during the hard winter of 2004-05 (bad acorn crop); Callery fruit ready for the birds and squirrels in Ridgeway Shopping Center; a young escapee along a driveway near Ridgeway Shopping center, a host of escapees along the fence to an abandoned construction project locally known as "The Hole in the Ground". Stamford CT, 2004-2005

THE THREAT TODAY: Yet, here in Connecticut, where we're probably no better or worse than most other folk, the landscapers and plant nurseries are still singing the tree's praises. Our state agricultural university is still recommending Callery pears as street trees and doesn't have a caution on its site that the tree is potentially invasive. They say Pyrus calleryana is "overused in the landscape, leading to monotony and boredom. The rigid habit of the plant also makes the species appear out-of-place in most situations. Other plant choices should generally be investigated when P. calleryana is called for. " And our newly-minted anti-invasive plant law does not list this menace. The bad news is that there are many popular alien garden plants which threaten our native species as much as the Callery children, and nothing is being done to stop their spread either. Why????

The sad fact is that the economics that drive the politics result in nothing getting banned for sale as an invasive until the plant is a proven problem, raging all over the countryside. By that time, the ban on new sales is almost silly because there's no way to undo what's been done. Face it, we are not getting rid of loosestrife, ailanthus, porcelain berry, garlic mustard, Asiatic bittersweet, Norway maple, mugwort, rosa mulitflora, wineberry, Japenese beetles, gypsy moths, chestnut blight, the Norway rat, … need I go on with the list?

Even if every homeowner uprooted every one of these proven bad guys on their property, AND we paid billions to sweep the forests, and streams, and ponds, and meadows clear of them, AND figured out how to do this without killing off the good guys, AND managed to cope with the 5- to 50-year seed banks already in the soil, there would still be a few of the known bad guys lurking in the alleys and dumps, ready to spread. We can not get rid of the invaders once established; all we can do is fight them off enough to let the natives have a share of the land, to help preserve precious bio-diversity.

PICTURE: Callery pear cultivar in the new snow, Hoyt Street Alley, Stamford CT, December 2005

BE A GREAT AMERICAN GARDENER: What we can do is BUY AMERICAN. Whatever your stand on Fair Trade and buying merchandise from abroad, when it comes to plants, if we buy American for the yard, we give our natives a chance and preserve their genes for the future, while providing familiar food for the wild critters. If enough of us chose to be Great American Gardeners by insisting on native plants, especially those that feed our critters, the nursery trade will have no choice but to come around. ("Native", by the way, means "to your area" -- west coast stuff can become invasive on the east coast and vice versa.)

Perhaps, it is impossible to stop the invasive species disasters-in-progress, or even the new ones to come, as the nursery trade economics are driven by finding the next "new, different, better, imported, fast growing, easy, hardy" whatever. Indeed, it may even be unwise to do so, at least as to non-allelopathic (plant-kiling) plants that feed the wildlife, since the real enemy is a monoculture and the more invaders we have fighting with each other, the more bio-diversity we will have. (Now, that's a thought that some will see as radical!)

Perhaps, it is too late to stop the internationalization of our forests and roadsides. One day, we may simply abandon the wilds to a riot of alien species, which have wiped out our native flora and fauna except the hardiest, but which have created a new bio-diversity of their own. Since our most aggressive species have become invasive abroad as well, the result may be that, worldwide, the wild places in the temperate zones share a single common set of international flora and fauna. Should such a day come, then the Great American Gardens will be havens for the native treasures too delicate to compete with the international thugs.

NATIVE ALTERNATIVES: Great natives with pretty flowers and/or great fall color and fruit for the critters include: crabapple, shad (serviceberry), hawthorn, redbud, blueberry, dogwoods, viburnums, juniper, holly, bayberry, smooth sumac, and winterberry. Magnolia are a favorite for song bird nesting. In each case, make sure you're getting the native American plant -- not a "new, better, different" foreign cousin.

PESTS: If you're luck enough to have a fruit tree of any kind, sooner or later, you're going to run into a range of pests that a healthy tree will fight off on its own. You may be tempted to use a spray or chemical compound. If you believe that he never had sex with “that woman”, that there were weapons of mass destruction, and that controlled substances which the doctor prescribes on the advice of a cheerleader-turned-salesperson are good for you, then you probably also believe that garden chemicals are a good thing, especially if “natural and organic”.

The sad part is that, long run, gullible homeowners will do probably do more damage to the environment with the backyard chemical warfare than all of our big-time politicians. The bottom line is, even if the chemicals didn't cause all kinds of side problems, they kill the bugs' natural predators and breed a bug immune to the chemical. Down the road, you can't kill the bug anymore and its natural enemies are all dead. Good going. The Great American Gardener way is to help the tree be healthy, encourage the predators, and tolerate a reasonable number of pests.

PS: Speaking of things not to be believed: Callery cultivars are often sold today with the claim "no edible fruit". Don't be fooled. "No edible fruit" translates into "humans don't eat the fruit but the squirrels and birds will".

PICTURES: Callery cultivars about town, Stamofrd CT Nov-Dec 2005, April 2004

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return to home page Photo credits: Sue Sweeney

© Sue Sweeney 2005

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