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New developments could be making you sick
By Dan McCue
Staff Writer
Is all the development in the area making you sick? It very well could be, according to Tom Ogren, a nationally recognized horticulturalist and creator of the world’s first plant-allergy ranking system.
Called the Ogren Plant Allergy Scale, his system is currently being used by the U.S. Department of Agriculture and a host of organizations to develop allergy rankings for all major U.S. urban areas.
In fact, the Asthma and Allergy Foundation of America recently ranked Charleston 24th out of 100 cities across the nation it called the most challenging places to live for people who suffer spring allergies.
Last year Charleston ranked 31st; a year earlier, 41st.
So what does all this have to do with development?
Ogren believes the newer the urban landscape, the more allergenic it is, primarily because of disturbances in pollination regarding plant genders.
“What’s happened over the past 40 to 50 years is that because people don’t want to deal with a lot of yard litter, dropped fruit, seed pods and the like, we’ve gotten into the practice of planting only male trees and shrubs,” Ogren said.
“The problem with that, and one that’s only recently been recognized, is that male plants are responsible for most of the pollen in the air,” he continued. “We’d all have been a lot better off if people were encouraged to plant females or those plants with both male and female parts.”
Ogren asserts the planting practices—practices once wholeheartedly endorsed by the USDA—are the chief reason allergy sufferers in the United States have grown from 2% of the population 50 years ago to more than 38% today.
The USDA reports that these allergies are having an enormous economic impact, costing the nation’s health care system $18 billion annually. The agency also reports that in 2002, the last year for which the statistic is available, approximately 14 million office visits to health care providers were attributed to allergic rhinitis.
The earliest reference Ogren can find to the practice of landscaping with a selection of male rather than female plants is the USDA yearbook for trees and shrubs of 1949, he said.
“At that time, USDA yearbooks were incredibly valuable horticultural tools containing articles by dozens of respected experts. The information contained in them was progressive and cutting-edge science,” Ogren said. “The problem is, in this case, planting only male plants was bad advice. Nobody had thought of the allergy component to it, and as a result, as an idea, it was a real turkey that has come home to roost.”
In short order, universities began endorsing the concept, and nurseries began to rely on grafting techniques to reproduce a steady supply of male plants to be used in parks, subdivisions and the backyards of new homes.
“Unfortunately, the approach lead to the promulgation of only pollen-producing male trees accompanying development, so people got less well in direct proportion to the new tidiness of their yards,” Ogren said. “The sad thing is the same goal—without the allergies—could have been achieved by planting only female plants. Without the males, those trees would not produce seeds or fruit.”
The allergy backlash has proven worst in the western United States for an ironic reason, Ogren said. People with respiratory conditions used to move to the tree-sparse west to improve their health, but as they moved in, they began to plant trees and shrubs—male plants—in their new communities.
As a result, their allergies essentially followed them. Over the past decade, several cities in that region—Albuquerque, N.M., Tucson, Ariz., and Las Vegas, Nev.—have adopted ordinances prohibiting the planting of male plants or allowing them to be planted only with their female counterparts.
Of course, there are those who question whether Ogren’s conclusions would apply to a community such as Charleston.
Steve Livingston, the city of Charleston director of public parks, described Ogren’s conclusions as “a little offbeat, but interesting.”
“The local take on this issue, for all practical purposes, with very few exceptions, is we use native trees and shrubs,” Livingston said. “The reason we do that is because we live in a very vulnerable environment.
“We have unique soil conditions, salt air, hurricanes, and what we’ve learned is that native trees simply do better here,” he said. “Most of our native tree species also happen to be self-pollinating varieties that have both male and female characteristics.”
But the city doesn’t regulate every tree planted in a new development or by a private homeowner or agriculturist. While it has technical review of planning proposals, its interest in trees is strictly related to the public aspects of proposed development plan—streetscapes and parks, Livingston said.
“If anything, I think development here reduces the number of trees and, theoretically, the level of pollen,” he said. “In fact, I think we do everything we can to reduce the number of trees that are taken down.”
Ogren, however, was steadfast in his contention that the percentage of male to female trees, not overall numbers, is the determinate of how potentially allergy-inducing a development is.
And even tree varieties native to the region, such as the dual-gender Honey Locust, have been cultivated by grafting over the years to produce plants that have only male characteristics.
“The tip-off is in the marketing,” Ogren said. “If you see the words ‘podless,’ ‘fruitless,’ ‘seedless,’ ‘low maintenance’ or ‘litter free,’ you’re guaranteed to be planting a male rather than female plant.”
The good news, from Ogren’s perspective, is that reversing the trend and reducing a region’s allergens is readily doable.
“The first step is to make a commitment to planting female trees. A number of species, including willows, cottonwoods, aspens, poplars, red and silver maples, cedars and junipers, come in each gender, so you can still achieve the look you want in landscaping,” he said.
“Another thing to remember is to capitalize on your opportunity to replace trees,” he said. “It’s rather shocking, but horticulturists estimate that the average life of an urban tree is only seven years, so over time you can create a more balanced urban environment.”
Ogren believes striving for a more balanced urban environment should also play a part in urban tree removal decisions.
“What community doesn’t have trees cracking sidewalks?” he asked. “What I tell municipal planning committees is to consider the gender of the tree in questions, along with other factors.
“If the tree in question is a large female, you might want to seriously consider saving it, whereas if it’s what I call a ‘highly allergenic male clone,’ I’d seriously recommend taking it down,” he said.
Finally, Ogren said, going against a 40-year flow and planting female trees or a ratio that includes more female than male trees can be a selling point for a new development.
“People are starting to market communities on the basis of their allergy-free landscapes,” he said. “We’re seeing that particularly in the west, and in some cases, even in regard to people selling private homes.”
Dan McCue is a staff writer for the Business Journal. E-mail him at dmccue@charlestonbusiness.com.
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