Letter from Washington — From the September 2015 issue

Weed Whackers

Monsanto, glyphosate, and the war on invasive species

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This anti-invasive mania is not merely a local phenomenon. It is the official position of the federal government, as expressed by the State Department, that “invasive alien species pose one of the most serious threats to our environment, affecting all regions of the United States and every nation in the world.” In February, National Invasive Species Awareness Week was celebrated in Washington, complete with a reception on Capitol Hill. Last year, the federal government spent more than $2 billion to fight the alien invasion, up to half of which was budgeted for glyphosate and other poisons.

That’s small change, nativists argue, when measured against the damage such interlopers inflict on the national economy. The Department of the Interior claims that the annual tab is $120 billion. But this number comes from a 2005 report by David Pimentel, an ecologist and scholar at Cornell, whose dislike of aliens apparently extends to the human variety, as evidenced by his public opposition to both legal and illegal immigration. Pimentel extrapolated at least some of his findings from such dubious assumptions as the dollar value of grain consumed by each rat in the United States. In an earlier paper, he concluded that cats were costing us $17 billion every year, after calculating that our furry (and, in his view, non-native) friends kill an annual 568 million birds, and arbitrarily valuing each bird at $30.

Eucalyptus trees in California by Chad Ress

Eucalyptus trees in California by Chad Ress

On close examination, other examples of the damage said to be caused by exotic invaders look no less questionable. The supposedly supercombustible eucalyptus, for example, survives fires that consume surrounding plant life — and rather than unfairly appropriating water, the tree actually irrigates soil by absorbing moisture from the coastal fogs through its leaves and funneling it out through its roots. (Though still cited as the prime culprit in the devastating 1991 Oakland firestorm, the eucalyptus was in fact cleared of responsibility in a FEMA report.) Monarch butterflies belie its reputation for repelling wildlife, the eucalyptus being their favored wintering abode in California.

As for the tamarisk, it consumes no more water than the beloved cottonwood, native to the Southwest. Nor, contrary to rumor, is it inhospitable to other species, as certified by the endangered southwestern willow flycatcher, which delights in roosting amid the tamarisk’s foliage. According to Matthew Chew, a historian of biology at Arizona State University, the tree’s sorry reputation dates to a ploy during the 1940s by a local mining corporation, whose operations required enormous quantities of river water — which had already been allocated to local farmers and other businesses. The solution was to generate studies demonstrating the heinous quantities consumed by the thirsty tamarisk. The destruction of the trees would theoretically free up huge quantities of “new” water in the rivers, which could then be used by the selfsame mining corporation.

Then there is the zebra mussel. This immigrant from the Caspian Sea is a perennial target of the nativists, thanks to its tendency to reproduce in vast numbers, encrust jetties, clog water-intake pipes, and crowd out God-fearing American mussels. But zebra mussels have successfully filtered pollution in the notoriously filthy Lake Erie and other waterways, thus promoting the revival of aquatic plants. The mussel also feeds a growing population of smallmouth bass and lake sturgeon.

It is the common reed, however, that has inspired one of the most determined and dubious campaigns of extermination. Phragmites is accused of robbing other plants, fish, and wildlife of essential nutrients and living space. Delaware has responded by spraying and respraying on an annual basis a 6,700-acre expanse of the Delaware River estuary with thousands of gallons of glyphosate-based weed killer. In 2013, locals in the Hudson River community of Piermont, New York, discovered a plan to destroy a 200-acre reed marsh fronting the town. Outraged, they fought back. “We love the marsh,” an indignant Marthe Schulwolf, who is active in opposing the scheme, told me. “It’s beautiful, a living environment, with lots of wildlife, and it protected us from the Hurricane Sandy storm surge.” The townspeople were especially alarmed to learn that the state’s “toolbox” for eradication included heavy spraying of herbicides — glyphosate being the customary choice — right next to two playgrounds.

As usual, the nativist dream of eradicating the interloper is intertwined with a fantasy of restoring the landscape to its “original” condition. The common reed has also covered vast stretches of the New Jersey Meadowlands, to the irritation of nativists who yearn for the return of the original cordgrass. Peter Del Tredici, formerly a senior research scientist at Harvard’s Arnold Arboretum, points out that the New Jersey Turnpike bears much of the blame: by blocking tidal flows, inimical to phragmites, it has allowed the reed to flourish. Ripping out the highway would bring back the cordgrass soon enough. “Meanwhile,” he adds, “there are over five hundred landfills in this area that are leaking nitrogen and phosphorus, and phragmites is actually cleaning the site up.” In any case, he said, the very idea of “re-creating a lost landscape is an impossibility, because the conditions under which these landscapes evolved no longer exist. The world is a totally different place as a result of human activity. There’s no going back in time.”

Mark Davis, a professor of biology at Macalester College and a frequent critic of anti-invasive hysteria, put it more pungently. “It’s the same perspective as ISIS wanting to re-create the seventh-century caliphate,” he remarked. “It’s ecological fundamentalism, the notion that the purity of the past has been polluted by outsiders.” Far from crowding out native species, he argued, invasives tend to move into areas that have been ravaged, or at least disturbed, by human activity. They are, in other words, a symptom, not a cause. Cogongrass is one striking example, but the same pattern recurs with many vilified species. Ailanthus, a salt-friendly seaside tree from China, spread inland from the East Coast along the fringes of America’s interstates, tracking the salt religiously spread by highway departments during winter snowstorms.

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is the Washington editor of Harper’s Magazine and the author, most recently, of Kill Chain: The Rise of the High-Tech Assassins.

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