‘An ecological disaster’: Emerald Ash Borer infestation in South Dakota

KELOLAND.com Original

SIOUX FALLS, S.D. (KELO) — Treat ’em or lose ’em. That’s the only course of action for your Ash trees, at least for those living in areas with identified Emerald Ash Borer populations.

What exactly is an Emerald Ash Borer (EAB)? This tiny little beetle that can fall a 60-foot tree? To find the answer, KELOLAND News reached out to Professor John Ball, an entomologist and Forest Health Specialist for the South Dakota Dept. of Ag and Natural Resources.

According to Ball, the EAB is an invasive species, brought over accidentally from China around 1992.

“It came over, it appears to be, in dunnage — wood that’s sole purpose is to hold contents in place so that they don’t shift,” says Ball. “What used to be a very common practice is when the ship docked, they’d just throw it all out at the dock, and it would pile up there, and darn if some beetles didn’t make it over.”

Currently, Ash trees cannot be moved in Sioux Falls. This freeze is in place from Memorial Day through Labor Day, as transportation of the trees can lead to the artificial spread of the infestation. If you do need to move one, Ball says to contact the City to request a permit. It is possible they will send someone out to check the tree for EAB.

Ball says that the EAB in Sioux Falls are just starting to emerge from their burrows and fly.

“They like to fly between 10 a.m. and 3 p.m.” Ball says.

This is when it’s sunny and the air temperature, around 70-80 degrees, is ideal for them. Ball says that when temperatures climb into the 90s, you’ll be unlikely to see them.

The insect itself is small; about a half-inch long, torpedo shaped and a bronze-green color. Ball says these are not to be confused with their cousin, the Jewel Beetle, which also lives in the region. He says Jewel Beetles are wider and speckled. Jewel Beetles are native to the area and will not harm healthy trees.

John Ball shows an Emerald Ash Borer he’d caught that morning, balanced on the tip of a pen knife.

Ball says this current infestation of EAB appears to be the result of a single introduction. “Some beetles came over once,” he says, “it hasn’t been a continuous flow of beetles.”

This encroachment was not immediately noticed either. “Dead Ash trees are not uncommon anywhere,” says Ball. Because of this, he says people didn’t immediately notice that the cause was this foreign beetle. This led people to cut the trees down themselves, hauling them as firewood from the initial site of infection in Michigan up to their lake cabins and campgrounds across the state, spreading the EAB all the way.

“In 2001, an entomologist by chance walked by one of these dying Ash trees and noticed a de-shaped hole in it.”

Ball says such holes indicate an agrilus, a genus of jewel beetles. Inspecting further, this entomologist discovered a mystery beetle, which he sent as a sample to the de-facto agrilus expert, who was in the Czech Republic, where it was identified as the Emerald Ash Borer.

“Agrilus insects are nature’s recyclers,” says Ball, describing their natural function in their homeland. “They take a tree that is dying and kill it real quick.”

This allows the tree to be broken down and fed back into the ecosystem. Ball says China has plenty of healthy Ash trees, and that there, the EAB only attacks the sick trees.

The problem, he says, is that the Ash population in North America does not have the defense systems in place that their relatives in China do. These defenses help keep the EAB from attacking healthy Chinese Ash trees. Put simply, due to their lack of defenses, almost every Ash tree in North America looks like a sick Ash to the EAB.

Ball took care to point out that this infestation is not the direct fault of the Chinese.

The true culprit: International trade.

“We’ve shipped pests to Japan which have devastated their forests; we’ve shipped insects to China; They’ve shipped things to us. Unless we ban international trade or put everything in a plastic bag, some of this is inevitable,” Ball said.

“The Chinese were very open and helpful trying to manage this, it was just inadvertent,” he says. “We’ve also moved things to China.”

A big problem, says Ball is that only 3% of dunnage used in international trade in the U.S. is inspected.

“Money is well spent in my eyes to go through and check [the dunnage], because imagine if we’d caught this. We could have saved a lot of trees.”

But it’s now too late to save the Ash.

“There is no win,” says Ball, going on to hold Chestnut Blight up as an example. “Chestnut was the most common tree in eastern North America; one in four trees,” he says. “It was said that a squirrel could jump from the Atlantic Ocean to the Mississippi River just on Chestnuts.” But the Chestnuts, by and large, are now all gone.

“In the late 1800s, somebody accidentally introduced Chestnut Blight from China — and by 1950 it had wiped out Chestnut in North America.”

John Ball

Ball says some Chestnuts have survived which grew outside the natural range, with no others nearby to infect them. “But you walk through the Appalachians,” he says. “Count how many Chestnuts you see. You can probably do it on one hand.”

Ball says that Ash trees and the EAB won’t be going anywhere, though that should be taken as little comfort.

“What happens is it kills most of the trees, and some continue to sprout so the disease is always there — you go back to ground zero (Michigan), and I can show you some Ash 30-feet tall. And they’re infested, and they’re going to die, but they keep seeding. So you’re always going to have Emerald Ash Borer. It’ll be in Sioux Falls for a hundred years.”

In real terms, Ball says the tree as it exists will disappear. Any tree left untreated will die, and any new tree that grows will be killed before reaching its potential.

As a species, “Ash will become a shrub,” says Ball. “It’ll be numerous, but it’ll be a shrub out behind your garage rather than a tree in your yard.”

This change will have consequences.

The removal of the Ash species as it exists from the environment will send ripples through the ecosystem.

“It will never come back to the way it was,” says Ball. “There’s a lot of other organisms that depend on Ash, and they’re going extinct as well. If your food source was Ash and Ash is gone, how are you going to survive.”

“Long-term, this is going to have a major impact.”

In terms of animal life, Ball says you may begin to see fewer birds of certain species which relied on Ash trees for their homes, but the biggest impact most of us are likely to notice on the face of things is the loss of wind-breaks provided by groves of Ash trees.

“It’s going to be devastating over about the next two decades in South Dakota.”

Eventually the Ash will mostly disappear and its place, at least physically, will be filled by another species. This, Ball says, will likely be the Hackberry.

“They seem to come in at about the same point in a forest’s life, they seem to tolerate about the same light levels, and so Hackberry is what you’re going to see replacing it, much as oak has replaced Chestnut.”

While Hackberry may grow in a similar fashion and fill the gaps left by the Ash, it will not be a true replacement. It will not fill the needs of the species who once relied upon the Ash.

“It would be like replacing dogs with cat, which I never would do,” says Ball.

The loss of our Ash is a tragedy and a disaster, but Ball says it is not the worst-case scenario.

“One thing that scares a lot of people, including myself; what if something comes over that kills Ponderosa Pine? That’s the let’s stay up at night and worry sort of thing.”

Ponderosa pine is the primary tree in the Black Hills, and also grow across the Rocky Mountains and throughout the west to California. “Imagine the Black Hills going through this on an exotic pest,” says Ball. The Mountain Pine Beetle, he says, which has caused damage to the forest five times since the 1890s, is native to the Hills. “At the end of each [infestation], you still have a lot of pine trees. It’s natural, that’s what happens — but imaging an exotic threat that could flat-out kill Ponderosa Pine trees. Pine is common in a lot of countries. China has vast pine forests.”

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