Nov 16, 2007

Drought and Elm Disease in The Fifties

In my memory, our house at 37th and Cottage Grove always looms very large, though I know it was only a modest four-bedroom affair. Being a corner property, there was a big porch both on the south and east sides, and over half of the eastern porch there was a second story sleeping porch. Our yard seemed big back then, too, but it wasn't huge either, less than a quarter of an acre - but big enough to have place for a huge oak, a huge cottonwood, three maples, and in the back yard a wild cherry.

Across the street stood the Grace Methodist Church, a large red brick affair standing in a vast expanse of grass with at least ten huge elm trees. Further down cottage grove both to the east and to the west the street was lined with elms, also huge. And there was at least one elm tree in every yard from 31st Street to 42nd Street. This meant that in the summers our neighborhood was shaded and – I hestitate to use the word "cooled" because the summers were so damned hot in the 50's – protected from the parching sun by trees.

Driving through the neighborhood thirty years later, I noted that all of our trees save the cottonwood were still standing, whereas all of the grand elms in the neighborhood were gone. In fact, by the early 1970's the whole of Des Moines had changed radically. Where once the grand trees of my childhood had stood, nothing was left. A town that had once been beautified by her magnificent trees was now stripped naked, only to reveal that under her elegant green clothes was an uninteresting, heartlands town.

The years from 1950-56 were drought years in the mid-west. You can read about it in the history books. For seven summers in a row, from early May to the end of September, there was virtually no rain anywhere in the mid-west. At least no usable rain. There was of course the occasional thunderstorm and the occasional tornado, but never with the kind of sink-in rainfall that helps the farmers. When a thunderstorm hit, it would rain so hard you couldn't see across the street; wild winds thrashed the trees; the lightning flashed and the thunder roared so intensely you couldn't tell which lightning bolt belonged to which thunderclap; the streets flooded; the flowerbeds flattened – but it would all be over in a few minutes or a half hour ... as soon as the storm had passed the rainwater drained off in the sewer system, and the ground was again as dry and the air as stifling as had been before.

Already in the mid 50's we started hearing about the dread Dutch elm disease (also known as DED, in the literature) DED showed up in New England around 1930, killing millions of elm trees in the north-eastern US, and slowly spreading west and south. By 1950 it had showed up in Michigan, and in the late fifties and early sixties it hit Iowa. I have never seen it mentioned in any of the the articles I have come across, but after a six-year drought Iowa's trees must have already been in a state of severe environmental stress when the DED epidemic started, making them less resistant.

In the quarter of a century between the DED's arrival in New England and it's arrival in Des Moines, natural resource management had learned a bit about limiting the impact of the disease, which was caused by the spread of a fungus by a nasty little dutch bark beetle Scolytus multistriatus, who promptly taught the trick to his American cousin Hylurgopinus rufipes who (due, no doubt, to superior local savvy) was even better at it.

And in Iowa, a very elmy place indeed in 1950, the westward march of the disease was closely monitored from year to year, but nothng was actually ever done about it. Whereas Detroit Michigan, one of the first big midwestern cities to be hit, had actively tried to do sometning about DED and saved a lot of trees there – at least for a time in Des Moines we did nothing. I read once that between 1960 and 1970 Des Moines lost 250,000 elm trees. Detroit, that did something, was smart and Des Moines, that didn't, was dumb, right?

Well, let's not be hasty. Looking back, maybe it was Des Moines that was the smart one: Detroit acted, Des Moines didn't. Des Moines lost it's trees quickly, Detroit lost them slowly. But what do we mean by "doing something" about DED?

What they did in Detroit was to spray elm trees intensively with a pesticide called dichlorodiphenyltrichloroethane otherwise known as DDT. Until about 1970 or so, killing the little beetles that were spreading the fungus was the only containment strategy known. The problem, however, was that DDT wasn't just killing the little beetles, but also a lot of beneficial birds, insects, and other wildlife. Normally, birds are the beetles' only natural enemies: you take away the birds and the bugs have a ball. And it wasn't just beetles and birds that were being killed, people were being impacted too.

In 1974, when my mother died of leukemia, several of the doctors reckoned that a probable cause of her illness was her exposure in her childhood to the massive DDT spraying in the wetlands of New Jersey. In the short term, the DDT probably saved a lot of lives by more or less exterminating malaria in the area. But on the longer term, it also exterminated a large number of bird and fish species and probably my mom – who ironically had already survived both malaria and typhoid fever contracted in the wetlands of NJ.

In the 60's, at least in part due to raised public awareness about the environmental impact of DDT as the result of books like Rachel Carson's Silent Spring, the indiscriminate use of DDT was reduced and finally eliminated. After 1970, some forest management experts were bright enough to try using fungicides to kill the fungus instead of pesticides to kill the beetles. But both in the case of insecticidal and fungicidal treatment, the long term diagnosis is simple and similar: treatment may prolong the life of a tree, but a tree infected with DED will sooner or later die of the disease, and the disease will move on to another tree.

But more to the point, as a child I have to consider myself pretty lucky in a number of different ways: I missed WWII; my childhood happened in a heartlands city like Des Moines that still had its green canopy of towering elm trees intact; and, at least for seven years, it almost never rained in the summers. The conflicts and cruelty of both the preceding decades and the decades to come, I didn't have to deal with.

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