|Emerald ash borer-damaged tree on Bryn Mawr Avenue in Chicago.|
That said, despite my personal interest, I'd have never thought to explore the borer situation in Chicago in detail. But my editor asked me to, and I was happy to comply, if unhappy at what I found. The news is not good:
|City worker Arce Vales inoculates an ash tree in Chicago.|
It is healthy, so far — a little woodpecker damage — but if you want to see the grim fate awaiting this tree and every one of the 85,000 ashes on public streets in Chicago, all you need do is look west, where a few feet away stand two ash trees ravaged by the emerald ash borer, the blight that arrived from China a dozen years ago, landing in Michigan in 2002, and has been eating its way southward since, decimating ash trees in the Midwest — 20 million trees have been killed so far in Michigan, Illinois, Indiana and Iowa — and causing billions of dollars in damage.
An estimated 1 million trees in the greater Chicago area will be dead within five years if not treated, and the blight might end up costing $50 billion nationwide by the time it runs its course, when you factor in the expense of treating healthy trees — chemical inoculations will keep the beetle away, but they must be repeated every few years — plus removing diseased trees and replacing them, plus lowered property values on suddenly treeless streets.
The bark of a blighted tree on Bryn Mawr is pulled off with a gentle tug by John Lough, one of the city of Chicago’s four full-time foresters, to reveal the telltale S-shaped trails the borer nibbles.
Beside financial cost, the infestation is an ecological disaster.
“It is,” he said, “widespread throughout the city.”
Before the frost, the city finished inoculating 37,000 trees against the ash borer. Some municipalities have given up on their ash trees; not Chicago.
"The benefits we receive from our ash trees are immense," Lough said. "They make a huge contribution to the urban canopy. We'd like to save as many as we can, to preserve the environmental benefits. We're really fortunate this year for Mayor Emanuel's insightfulness and environmental connection to the situation. If he hadn't done anything, these would all be gone."
The treatment lasts for two years. The 20-year-old autumn purple ash on St. Louis, in front of a sign for Northeastern University's campus, is still hearty, and last month park district worker Arce Vales knelt and drilled eight holes around its base.
She injected three pressurized puffs into each hole.
Vales was hired in January, one of 37 inoculators who have been going around the city treating ash trees.
Another 37,000 ash will be inoculated in the spring, and if you do the math, you'll notice that 10,000 ash trees will not be treated because they are too far gone. They'll have to come down.
In Illinois, tree experts have been watching the blight march southward.
"Basically the northern third of the state is infested," said Jeff Squib, a spokesman for the Illinois Department of Agriculture.
He said the beetle was first found in Kane County in 2008, but whether that was because the infestation started there or because that's where the ag department has its DeKalb nursery program to notice it is an open question. The ash borer cannot fly far, and much of its quick spread is thought to be because of human activity, such as transporting firewood. The borer was just detected in Colorado, for instance.
"It didn't fly to Boulder," said Stephanie Adams, a research specialist in plant health care at the Morton Arboretum. "Humans are a really big problem when it comes to invasive species."
The city of Chicago has 560,000 trees on public land; 17 percent are ash. But those are just the city's trees; the Chicago region has an estimated 12 million trees, and 8 percent of those are ash - a million trees.
And if that seems like a big share for one kind of tree, some communities have twice that: in Arlington Heights and Wheaton, a third of the trees are ash.
Other towns are feeling a budget squeeze; Evanston couldn't keep pace with the speed of the borer invasion and cut down 500 trees without yet replacing them. Hanover Park cut down 1,100 ash and so far has planted only 100 replacements.
But then varying tree selection is not something communities did well before the emerald ash borer. Despite previous historic blights such as Dutch elm disease or, more recently, the Asian longhorn beetle, which attacked maples, the lesson was not learned. Ash are cheap, fast-growing and pretty; some subdivisions around Chicago are 90 percent ash
When you project what this half-inch bug is going to do nationwide, the cost of treatment, removal and replacement becomes enormous.
"I've heard figures of $47 billion nationwide," said Scott Schirmer, manager of the Illinois Department of Agriculture's Emerald Ash Borer Program.
The cost to each community can be considerable. Five years ago Carol Stream set aside $2.25 million to deal with ash-borer related problems.
Of course, what the cost is depends on what strategy is taken. Cut your ash down now and get new trees going? Or treat them and allow residents to enjoy them as long as they can?
Now that the Chicago area is infested, ash trees are considered doomed over the long haul.
"If an area has an infestation, all ash in that area will eventually succumb to the beetle," Squib said. "Once you start the treatments, you need to continue them. It's not a one-time treatment. You also need to realize eventually the tree will succumb to the beetle. Some homeowners will prefer to prolong the tree's life and therefore their enjoyment of it. Others will prefer immediate removal of the tree and replace it. Eventually, the beetles will move to the treated tree. But who knows? In some respects you're buying time, treating the tree to fend off the beetle. Perhaps an effective treatment will be discovered."
Some communities are not bothering to inoculate their ashes at all, deciding it is only expensively postponing the inevitable. Some are inoculating, but not to save the trees, just to stagger their removal and not have expanses of dead ashes.
"There's been a lot of questions whether treatment is worth it," Adams said.
You can't be in the tree business and not look at the long haul, and arborists are trying to do that when it comes to the emerald ash borer. Some communities are passing ordinances to prevent one type of tree from dominating their streetscapes ever again and perhaps fall victim to some future scourge on par with the borer. They're also trying to change residents' aesthetic view: For centuries, people admired uniform canopies of trees. With the risk of a whole genus of trees being wiped out by invasive predators, that might be a luxury that communities can no longer afford.
"All the same color, all the same size. You need to look at it from a dynamic viewpoint," Schirmer said. "[This crisis is] really providing an opportunity to make streets more interesting. A lot of residents live in the now, versus arborists, who have to look 20 or 30 years down the line."