Has it been a particularly miserable itchy, scratchy, sneezy, watery eyes allergy season for you in recent weeks?
It’s not your imagination. Pollen counts for Lancaster city have been in either the very high or high range for 17 of the 22 days of May for which The Weather Channel posted readings for trees, grasses and weeds.
One reason recent allergy seasons have been so bad is that rising temperatures and increased carbon dioxide levels from global warming in the spring are prompting vegetation to begin releasing pollen sooner, longer and with more intense allergens, according to the Asthma and Allergy Foundation of America. Some 50 million people, about 8% of adults, suffer from allergies in the United States.
If you live in Lancaster city, or other municipalities around the county where planned tree plantings were done through the years, you may be an unsuspecting victim of what California horticulturist Tom Ogren calls “botanical sexism.” As a result, city dwellers suffer much more from allergies than their rural neighbors, according to his research.
That’s because for many decades and at the recommendation of the U.S. Department of Agriculture, mostly male trees were planted along public streets and in parks in urban areas across the United States. The thinking was that female trees drop seeds, berries, acorns and other fruits, which would be an annual burden. Male trees, on the other hand, “just” release pollen which would be blown away by the wind or rinsed away by rains.
Big mistake, Ogren says, and urban residents are now suffering inordinately because of it.
Oren’s findings have gotten a lot of media play in recent weeks, especially after a quite visible glowing yellow haze rose above Durham, North Carolina, in April, coating the entire city in pollen. Residents dubbed the event a “pollenpocalypse.”
Did Lancaster city fall into this trap?
The last time there was an inventory, the city had 7,243 trees along streets and at least that many in parks. There are no records of how many are males versus females. Jim Bower, the city’s arborist since 1999, says the city now plants both males and females. But he acknowledges there are a lot of male trees out there and a lot of pollen.
He said reading Ogren’s observations about the dangers of male dominance among trees in cities was disturbing and makes sense. And he said he will take up the idea of planting more female or pollen-free male trees with the city’s Shade Tree Commission.
“You don’t want to see people walking around in masks like in China,” Bower said. “This year there was so much stuff floating around in the air. You get up in the morning and it’s all over your car.”
The city does have a ban on planting female gingko trees because of complaints about the smell of their fruit. This distaste of female ginkgo trees in the city goes way back. When a male exchange student with royal blood from Japan died unexpectedly at Franklin & Marshall College in 1895, his home country sent six ginkgo trees to the city in his honor, says Jerry Smoker on the Tree Treasures of Lancaster County website (lancastercountytrees.org).
Three females were planted at the college and the three males at Lancaster Cemetery. The stench from the fruit of the females raised such a ruckus that there were widespread calls to cut them down. Fearing an insult to Japan, the females were instead relocated to join the males at the cemetery, where they continue to grow.
The city does have large numbers —20 percent of all trees in one census — of red maple trees, one of the trees highest in pollen output. Red maple trees have both male and female parts so all release pollen.
And there are large numbers of white mulberry trees, one of the top pollen producers in America. In the early to mid-1800s, residents in Lancaster and other towns across Pennsylvania were encouraged to plant them to help the silk industry. Pollen output is so high that cities such as Las Vegas, Tucson, Arizona; Albuquerque, New Mexico; El Paso, Texas; and others have banned them.
“Male mulberry trees produce prodigious amounts of pollen that can cause allergies and trigger asthma attacks,” says Len Eiserer, a Millersville-area former teacher who created the Tree Treasures of Lancaster County website.
In addition to red maples and mulberries, other trees high in potent pollen include oak, ash, beech, birch, box elder, cedar, elm, hickory, mountain elder, yew and willow. Trees low in pollen include apple, cherry, dogwood, pine, hawthorn, mountain ash and serviceberry.
Lancaster city is a desirable place to live for many reasons. But escaping allergies is not one of them. Still, Lancaster avoided the Asthma and Allergy Foundation’s list of the 100 worst cities for allergies. Scranton, Philadelphia, Pittsburgh and Allentown did make the dubious list.
Ad Crable is an LNP outdoors writer. Email him at firstname.lastname@example.org.