Editor’s note: This is the first story in a two-part series about the emerald ash borer coming to South Dakota.
BROOKINGS – The emerald ash borer has not been found in Brookings, but it will arrive in the next few years, according to John Ball, a professor at South Dakota State University, an Extension forestry specialist, and a forest health specialist with the South Dakota Department of Agriculture.
The emerald ash borer was recently found in ash trees in northern Sioux Falls, and Ball estimates the insect has probably been there about four years.
Ball does not believe the borer is in Brookings yet and neither does Al Kruse, superintendent of Brookings Parks, Recreation & Forestry.
“Every tree that I’ve been asked to look at does not have the symptoms consistent with an infestation,” Ball said.
But he believes they are coming.
“It’s inevitable. The fact that we cannot confirm it’s in Brookings right now doesn’t mean it’s not going to be in Brookings someday,” Ball said.
When it hits, it destroys.
“It’s an exotic insect attacking native trees. And it will kill all of them. Eventually there won’t be an ash left in Brookings of any size, unless it’s being treated,” Ball said.
There’s no need to panic, but homeowners should start thinking about how they want to handle the problem: cut down their ash trees or have them treated, the two said.
Emerald ash borer
The emerald ash borer is an invasive species, Ball said.
“It is a beetle, a little less than a half inch long, torpedo-shaped, so it’s very slender. And, of course, is a metallic green color,” he said.
They originate in China; in fact, experts have narrowed it down to an area east of Beijing, Ball said, adding he’s been to China to see the insect.
“In China … the insect does what it’s supposed to do and that’s recycle dying trees into dead trees, which is a good thing for the forest,” Ball said.
The beetle has no effect on healthy ash trees in China.
The problem comes when the beetle travels out of its native environment. With high-speed travel methods, our planet is getting smaller and diseases and animals can move around the globe much more quickly, Ball said.
“Barriers of mountains and oceans mean nothing when you’re in a cargo ship or on an airplane,” he pointed out.
The emerald ash borer has a whole different effect on American ash trees.
“Unfortunately, when it arrived in North America, it recognized our ash trees as ash trees. In other words, they gave off the same chemical signature, but since our ash trees had never seen this insect, they have no defenses. So emerald ash borer can kill a healthy ash in this country or a dying ash in this country. It makes little difference to them,” Ball said.
The reason the emerald ash borer is a problem is the number of ash trees we have.
Kruse estimates that 30-40 percent of the trees in Brookings are ash, so the arrival of the invasive insect could drastically change the landscape. His crews have been counting the ash trees in the parks and on the boulevards and other city-owned property, and he figures the numbers are similar on privately-owned property.
“The reason the emerald ash borer is an issue is (so many) of all our trees are ash. If we only had two ash trees in Brookings, you and I would not be talking,” Ball said.
Containment
South Dakota has set up quarantines of raw ash wood in the Sioux Falls area, hoping to contain it as long as possible because the borer hasn’t been found anywhere but northern Sioux Falls.
“That’s our best means of slowing it but inevitably, somebody’s gonna move some wood, either they didn’t care or they didn’t know,” Ball said.
Wood isn’t the only way the borer can move.
“The insect can hitchhike on cars, so it does tend to follow transportation corridors (like Interstate 29),” Ball said.
And sometimes they have lots of help from humans.
He pointed out ash wood can still be purchased on Craigslist from Minnesota and Iowa, two places where the borer is known to be.
“There’s nothing saying that emerald ash borer could not arrive in Brookings because someone brought it over from Minnesota or Iowa,” Ball said, adding if you want to burn ash wood, make sure it’s from a local source.
The borer is moving fast around the globe due to international trade, but there’s another factor, as well.
“Only about 3 percent of all the wood shipments in the United States are checked for pests: talking about pallets, dunnage (wood used to keep cargo in place), the big spools,” Ball said. “There’s just not enough inspectors. There’s one area we ought to do more government spending because had we had more inspectors in place, we could slow the spread of some of these problems.”
He said it has cost $40 billion – yes, billion – to remove 100 million ash trees in this country so far.
“Forty billion dollars – that would hire another inspector or two,” Ball said.
How it kills
The adult female borer lays the eggs in the bark crevices. When the larvae hatch, they’re already living on the buffet table.
“Just beneath the bark is the tissue, we call it the phloem,” Ball said. “That carries the food manufactured by the leaves throughout the tree and obviously into the roots. That’s where this insect feeds is this phloem tissue, that’s the sweet part of the tree.”
The larvae keep feeding for months, and their population builds in close-by trees.
“By tunneling back and forth through it and in incredibly large numbers – literally hundreds – they very effectively sever that connection between the leaves and the roots. So the roots begin to starve; they’re not getting enough food to survive,” Ball said.
Once the root system dies, “it no longer takes up water; so if it’s no longer taking up water, the top dies,” he said.
“It doesn’t kill the tree in a year. It can take four or five years to kill a tree. It has to repeatedly attack it, so they call it a slow, lingering death,” Ball said.
Symptoms
“The first year a tree is attacked, it’s almost impossible to tell, unless you cut it down and take all the bark off,” Ball said. That’s why he can’t swear the borer isn’t in Brookings yet, “unless you want me to cut down every tree and look at them; but that’s kind of destructive sampling.”
One of the best ways is to watch the woodpeckers.
“They developed a taste for this little insect, and they will strip the bark off in search of it,” Ball said.
An occasional woodpecker tapping on your trees is completely normal, Ball said, but if you see patches of missing bark going around the trunk with woodpecker holes in it, that’s a sign the borer has moved in.
Even then, there’s no need to panic, because there’s still things you can do, say Ball and Kruse, such as treatments and planting new, diverse trees.
Contact Jodelle Greiner at jgreiner@brookingsregister.com.
John Ball photos:
Above is an emerald ash borer adult.
Shown below is an emerald ash borer larvae found in green ash in northern Sioux Falls.
Below, an emerald ash borer infested tree is shown with woodpecker pecks.
