Thursday, July 24, 2014

Emerald Ash Borer Finally in Baltimore, Relieving No One

Emerald Ash Borer trap.
Photo: Fairfax County Gov't
I suppose if I had been in charge of the Emerald Ash Borer beetle traps in Baltimore City parks for the last decade, I'll feel like quite the loser.  Not one bug in one trap in 11 years.   According to the Baltimore Tree Trust, that has now changed, with Baltimore City Parks and Recreation reporting that in the last month, the pesky Asian invaders have been caught in traps in two separate parks, miles apart.   To have not found a single insect in this bustling city of 700,000 people, rail, highway, and marine shipping in the last decade is actually a great accomplishment, not a failure.  However, nor was it a prevention.  And the City, known largely for our internationally significant rat population and of course, The Wire, now has a new pest.

Emerald Ash Borer damage.  Photo: Purdue University
Department of Entomology
According to Maryland DNR, a hefty population of Emerald Ash Borers arrived in Michigan, from Asia, in 2002. American ash trees - we have two species - have no immunity to the little green beetle, and it shows.  Our hardy ash trees - planted in many Maryland communities (300,000 in Baltimore alone, according to this article in the Baltimore Sun) after Dutch Elm disease destroyed America's favorite street tree - sat waiting for the Emerald Ash Borer to arrive.   And it didn't take long.   Maryland Department of Agriculture notes that a shipment of infested ash trees arrived in 2003 from Michigan.  By 2012, the beetles were destroying trees in nine Maryland counties.  In 2014, we're at nine counties plus Baltimore City.

The story of how the insect even arrived in Maryland illustrates why the United States has eradicated exactly zero invasive species, despite a century of effort and hundreds of millions of dollars spent trying to achieve just one complete removal.   According to Maryland DNR, the initial infested shipment into Maryland occurred when a nurseryman, fearful of the Ash Borer known to be ravaging Michigan, ordered a supply of native ash trees from a nursery in Tennessee.  Unbeknownst to him, his supply used remote "drop shipping," asking a wholesale supplier in Michigan to send the ash trees directly out of the Ash Borer's infestation area and into Maryland.   A plant inspector for the Maryland Department of Agriculture found the beetles, but it was too late - most of them had already left the DC-area nursery already.

Photo: Aldertree Garden
As scientists and citizens continue to try to understand what the most important values of urban forests can or should be, this latest infestation illustrates what we all try to ignore.  The swaths of low quality maple, ash, and willow trees, low-slung and half alive throughout our City parks, engulfed by invasive English Ivy, Chinese Multiflora Rose, French Wineberry and Japanese Knotweed....this is hardly "forest" at all.  These places are the last refuge for our urban wildlife, and a "green" place in which children can play - as long as they don't touch the contaminated water running through our degraded "streams,"  or the thousands of tons of illegally dumped trash that the City's unlikely to ever remove.  Or the millions of gallons of undetected, leaking sewage in the stream.   And now, the Emerald Ash Borer has arrived to remove 300,000 of our last native trees.

Perhaps it's time to stop holding our collective noses and pretending that "preserving" these areas in their current condition isn't benefiting our natural environment.  The Nature Conservancy, our country's largest conservation non-profit organization, certainly thinks so, and they've been aggressively removing Ash trees from their properties in the "Emerald Ash Borer zone."   Maybe we shouldn't count on an invasive species not happening again.  Maybe just pretending that "a tree is a tree" isn't working anymore.   Maybe it's time to fix our streams and plant resilient forests that will serve the next generation of Baltimore residents. Who's with me?

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