Street Trees Can Be Allergy Culprits

By Heather Legg

I read an interesting piece the other day in The New York Times by Thomas Leo Ogren,  author of “Allergy-Free Gardening: The Revolutionary Guide to Healthy Landscaping.” He talked about all the street trees that line our city streets, and suburban streets as well, and it did make me think.

In my neighborhood subdivision, along the main entry street, we have about a dozen or more Bradford Pear trees that line that street. It is beautiful throughout the year as they are full of fluffy white flowers in the spring, nice green leaves throughout the summer which change to firelit yellows and reds in the falls. But these lovely flowers cause a lot of misery with their pollen. These trees are very popular in the south not only in neighborhoods, but also in parking lots and shopping malls. Some people don’t like them because they see them as contrived and unnatural. They take the place of the indigenous trees that were cut down.

Of course, the south demands different trees than the other areas of the United States, but in theory, it is the same. Ogren states in the article, “Some trees shed huge amounts of highly allergenic pollen; others produce very little, or their pollen is only moderately irritating. Female plants produce no pollen at all. But arborists rarely take this into account. In New York City, street trees are selected only for their hardiness in winter; their resistance to disease, insects and drought; their ability to withstand smog; and their size, shape and color.”

What this means is that pollen is not taken into account, only sturdiness of the tree. Because the trees are planted in large numbers in small areas and of one sex (or monoecious species are used, those that have male and female flowers on the same tree), the pollen count is higher, but it makes for prettier trees.

Another problem with street trees is that the same species are often used, just like the Bradford Pears in the south and Norway Maples in the northeast. Because of this,  people are repeatedly exposed to the same pollens which increases chances of developing allergies. It would be much better health wise to use more variety of trees and those with low pollen counts in city planning.

Because so many trees are cut down to build streets, subdivisions, and shopping centers, developers like to replace them as it is more aesthetically pleasing and, bottom line, trees are good. But if more diverse ones could be used, it may help the pollen counts and help out those who become miserable in the spring, even though the trees are beautiful.

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