Ben there, done tha
Human meddling created pollen apocalypse
As someone who has the misfortune to suffer from environmental allergies, the late spring to early summer is not what I would refer to as my favorite time of year. Statistically speaking, there is a really good chance you can either directly relate to the sense of annoyance when pollen starts to fly or know someone who does. About 40 percent of people in the world suffer from some form of environmental allergy, ranging in severity from barely noticeable to life-threatening, according to the American Academy of Allergy, Asthma, and Immunology. It’s called AAAAI for short, and I think this might be my favorite acronym for an organization ever.
You may be surprised to learn that humans, in the last 100 years, have made things much worse for ourselves, and it all goes back to one sentence in a little known book. Nature and humanity have been co-existing for thousands of years with only minor reporting of allergies. In the 19th century, Charles Harrison Blackley is widely credited with being the first to discover the link between pollen and allergies. While allergies were well documented, they remained a problem for only a small portion of the population. Then, in the 1970s, a troubling new spike of environmental allergies emerged rapidly in the United States and has stuck around. So what changed?
Broadly speaking, trees in our world are classified as dioecious or monoecious. Dioecious trees have separate female and male trees within the species and monoecious have the characteristics of both male and female trees in one. Male trees release pollen, which is captured by the female trees. Elm, a monoecious species, was extraordinarily popular in America and Europe during the Edwardian Era (from the turn of the 20th century to the late 1900s). During this time it was very desirable to have rows of these stately trees lining roadways. Because elms both produced and captured pollen, these trees were particularly clean and produced very little pollen. In the 1930s, a fungus transmitted by bark beetles known as Dutch Elm Disease struck the American east coast. Over the coming decades, an estimated 75 percent of the roughly 77 million elm trees in America would succumb to the sickness. Numerous streets were bare and without shade, due to elms dying. It was a challenge for city planners to replant trees.
In 1949, the USDA’s published a book, “The Yearbook of Agriculture,” with a single sentence that changed the course of history: “When used for street plantings, only male trees should be selected, to avoid the nuisance from seed.” So, that is exactly what city planners all across the country did. The USDA had surmised that pollen would simply be blown and washed away by wind and rain. Pollen would be less of a civic burden than the clean up of seedpods or overripe fruit created by female trees. In retrospect, I find it hard not to chuckle at this conclusion. It must have seemed perfect at the time.
Consequentially, the new asymmetrical demand for the tree genders drove nurseries to start cloning male trees. Being faster than waiting for the trees to reproduce naturally, cloning prevented a backlog of unwanted female trees. Additionally, researchers discovered that through the use of cloning, a grower could make a monoecious tree devoid of female characteristics. After the 1949 guidelines came out, the USDA developed and released almost 100 new varieties of Red Maple (a monoecious species) over the coming decades and every single one was male-only. This is also how trees like seedless cypris and podless honey locust came into existence, both of which, have no way to reproduce other than through cloning. All of these male trees were planted across the country in the wake of the Elm die-off. For a while, it looked like we had finally cracked nature’s system.
After the post-Dutch Elm disease replanting, a couple of decades passed. The nationwide hoard of male trees eventually reached maturity. Then, starting in the 1970s, they began to bloom. Millions of male trees released tons of pollen with no female trees to catch and sequester it; thus the Pollen Apocalypse was born.
Once exposed to larger quantities of pollen than are normally found in nature, a big chunk of the population began to experience environmental allergies and asthma. While allergies have existed long before the 20th century, this consequential decision in 1949 has greatly exacerbated environmental allergies in the United States. What can we learn from this fiasco? No matter how much we have figured out solutions, the chance for unintended consequences remains.