Requiem for the ash borer (the Sunday column)

In case you missed it, here's my Sunday column about the Twin Cities' struggle in the face of a voracious invasive insect.

Last week marked a sad anniversary for the woods of Minnesota. On May 14, 2009, a dreaded beetle made its debut in Minnesota by eating through an ash tree in a St. Paul neighborhood.

The emerald ash borer has since infested trees in more than 1,300 places across the state, primarily in St. Paul and Minneapolis, but also in the bluff country down the Mississippi River.

Measured by its damage so far, the ash borer looks like something you could crush under your Red Wing boot. Those who look after our urban forests know better, having seen it defoliate Midwestern cities such as Toledo, Ohio, in a matter of years.

That's why parks departments throughout the Twin Cities have adopted plans to deal with the bug, all of which appear to be different forms of surrender.

The Minneapolis Park and Recreation Board has perhaps the most aggressive plan: Cut down every publicly owned ash tree, healthy or not. I did not appreciate what this would mean for my south Minneapolis neighborhood until I showed up at a community meeting last month.

Ralph Sievert, the city forestry director, sent around a bottle containing a pickled beetle, and another containing its larvae, the real villains, who carve tunnels under the bark until the tree starves to death. Then Sievert put up a PowerPoint.

So the park board is taxing its property owners an additional $1.2 million each year to cut down 40,000 trees over eight years. To its credit, the city will replant each one with a more diverse forest, avoiding the mistake made when the city planted more than 90 percent of its boulevards with American elms.

Sievert said the replanting also will rectify another mistake made when a different exotic scourge killed elms by the tens of thousands in the 1970s. The city replaced them with a single species on each block, thinking it would look better, but now dozens of blocks are all ash. The city will remove a few each year, to soften the blow. But it will take another generation before the streetscape is once again crowned by that green arbor we all love.

The idea of chopping down healthy mature trees did not sit well with some of the others in attendance. "That makes no sense to me," Marne Moe told the foresters. "There are so many benefits to big trees."

That argument has persuaded other cities to go easier on the chain saws. Under its plan, St. Paul will only cut down public ash trees that are diseased or weakened by some other cause, and it's also pumping pesticides into about 800 prize ash trees. Like Minneapolis, St. Paul can also condemn infested trees on private property.

Milwaukee is waging full-scale chemical warfare against the beetle, injecting 28,000 boulevard trees.

"It's tempting to wait and see," he said. But that makes it all the more important to take action now, before the infestation breaks out in hundreds of places across the city. "We still have time to do something."

I left the meeting and looked around in the early spring evening. It seemed every tree in my sight had the ash's distinctive bark, a woven diamond pattern. I knew that this spring, or maybe the next, or maybe the next, would be their last.

Like so many of these pests, the emerald ash borer is a side effect of globalization. They think the beetle arrived from East Asia to the port of Detroit sometime in the 1990s in a wooden pallet. I bet that pallet was carrying a shipment of plastic garden gnomes, or something equally stupid.

Dennis Garvin, the commissioner of Toledo's parks and forests, remembers the public reaction when ash borer first appeared in his city in 2005.

"In the first couple of years, we had everybody doing everything but chaining themselves to the tree," Garvin said. Within two years, ash trees by the thousands had turned to skeletons. "The last year, people were applauding for us as we would come up the street," he said. Aside from a few struggling hybrids, ash trees had disappeared from Toledo by 2009.