Sunday, July 15, 2007

Bradford pear, beautiful but breakable




How do we love thee? Let me count the ways. For thy beautiful (if malodorous) white flowers in April! For thy symmetry, thy cone-shaped crown! For thy rapid growth!

Bradford pear (Pyrus calleryana 'Bradford') is surely one of the most popular trees for planting in the eastern United States. But our collective passion for this tree leads to broken hearts, not lasting relationships. Bradford pear is genetically programmed for a short life that often ends catastrophically.

The tree splits apart in storms because of the way it is constructed. The limbs extend out from the trunk at very narrow angles. This tight-angled branching pattern traps bark between trunk and limb. Instead of knitting together as they grow, the trunk and limb are separated by bark, with no bond holding them together. If they don't split, Bradford pears can be expected to live for about 30 years.(1) Many disappear because of splitting long before reaching that age.



The Bradford pear at 937 Hillside Avenue was planted 10-12 years ago. The photograph above shows its condition after loss of one of its three major limbs in the fall of 2006. Notice that the other two limbs have begun to split apart. The photograph below shows the tree from the other side. The crack follows the line of trapped bark.




Below: the same tree on June 7, 2007.



Below: The same tree three weeks later.



Its neighbor at 930 Hillside, planted at the same time and pictured below, has been reinforced by steel bolts to help to hold it together. It illustrates the good looks that make Bradford pears so popular. Notice the narrow-angle branching.



The tree at the top of the page, on West Fourth Street just west of Plainfield Avenue, is rather a long-term survivor. It was planted in about 1990 by a civic group in front of what was then the Plainfield Health Center building as part of a beautification project. City Councilman Elliott Simmons was one of the planners and planters of that project (but the blame for the choice of Bradford pear falls on me, not on Councilman Simmons).
Also still attractive is a row of Bradford pears on Leland Avenue at Cook School.



The Bradford pears on the Randolph Road side of Muhlenberg Hospital have not done quite as well. They look like a row of amputees. In fairness, it appears that not all of the amputations were spontaneous. I would guess that someone has pruned some of them to try to prevent splitting. That sort of pruning is not at all easy to do in an effective and attractive way because all of the major limbs typically spring from the trunk at roughly the same height above ground. Worse, as the tree gets larger, those closely spaced branch points intersect each other. The corrective pruning, to the extent that it can be done, tends to eliminate the symmetry of the crown that is one of the tree's attractions.

The name "Bradford pear" looks as American as apple pie, but this Bradford shares no bloodlines with the governor of the colony at Plymouth. The tree is a Chinese import. Although Bradford pear is sterile, attempts to breed less split-prone varieties of Pyrus calleryana have yielded trees that are capable of reproduction. They interbreed with Bradford pear and their brood has become an invasive pest.(2)

Lou Dobbs hasn't tuned into this Chinese threat yet, but the USDA Forest Service hasn't missed it, recently honoring the trees as "Weed of the Week".(3) Invasive.org, a joint program of the University of Georgia and the USDA, offers this(4): "Do not plant Bradford pear. Seedlings and shallow-rooted plants can be pulled when soil is moist. Small trees need to be dug up or pulled out...ensuring removal of the root system. Large trees should be cut down and stumps treated with an appropriate systemic herbicide...or ground up to prevent resprouting. If cutting is not possible, trees can be girdled...by cutting through the bark all around the trunk, about 6" above the ground." How do we kill thee? Let me count the ways.


Copyright Gregory Palermo

3 comments:

Rob said...

YES !! Great post !!! KUDO's to you. I have caught and stopped so many people at Nursery's and advised them NOT to buy the tree they have on the way to check out. I quickly run through what you said and most are appreciative and go back to select another ( I usually advise a Cleveland Pear as it doesn't suffer the weakness of the Bradford...) Great post, glad to read it again !
Rob

beverly guest said...

living in georgia, I learned that the Cleveland pear tree is stronger and just as pretty as the Bradford pear tree

Anonymous said...

In all this gush over the beauty and frailty of the Bradford pear (and all of the Pyrus calleryana group) it has been overlooked that is a nuisance species that has become invasive in many areas, and SHOULD NOT BE PLANTED.