NATALIE YAHR: I’m Natalie Yahr.

MAX WITYNSKI: And I’m Max Witynski.

NATALIE YAHR: And we’re here talking about how Wisconsin is navigating a serious threat to trees across the state. Max, what sort of threat are we talking about?

MAX WITYNSKI: So I first noticed that something was wrong a few years ago, while I was driving through southeastern Wisconsin. On the side of the road, I was seeing a lot of dead and dying trees. And on some of them, woodpeckers had chipped the bark, making it lighter in some patches than others. Often the crown of the tree was dead, but lower branches would still be green.

NATALIE YAHR: And what was it? What was killing the trees?

MAX WITYNSKI: As it turns out, I was looking at the symptoms of an invasive insect, the emerald ash borer. It’s a beetle that was introduced to the U.S. from East Asia, and it spread from Michigan — where was first detected in 2002 — across the continent, killing trees everywhere it goes.

NATALIE YAHR: We wanted to find out more. So we spoke to some of the experts who’ve been working to counter this threat: an entomologist, an arborist, a tree protection specialist and Madison’s city forester. We also talked to some residents who are worried about their trees to understand the emerald ash borer’s impact here in Madison. Reporter Kathryn Wisnewski and I visited PJ Liesch, director of the Insect Diagnostic Lab at UW-Madison. PJ has been working with the emerald ash borer since before the beetle had even been detected in Wisconsin.

PJ LIESCH: So the adult beetle is roughly half an inch long. They’re a very brilliant metallic green color, kind of oblong and slender in shape. The underside has a hint of reddish, which we can see right there kind of shimmering in the light. It’s pretty when you see it. When you see what it does to trees, I mean, that’s a stark contrast because it kills these trees, and it’s pretty vicious. 

NATALIE YAHR: It’s not the adult that does the major damage to the trees. It’s the emerald ash borer in its larval stage. The larvae are not beautiful like the adults. He showed us one floating in a glass tube. It looked sort of like a cream colored, semi-transparent worm.

PJ LIESCH: And you can see this one is just over an inch or so long. And so these are feeding beneath the bark of the trees. And they’re feeding right where the critical tissues are that are transporting water and nutrients in the tree. And you end up getting all these tunnels. So this is ash bark that has been removed from a tree. You can see all the tunnels under there. So, in a way, it’s kind of death by 1000 paper cuts for these trees. One individual emerald ash borer isn’t going to kill the tree. It’s the cumulative action over the course of 2, 3, 4, 5 years that really does the tree in.

MAX WITYNSKI: That sounds pretty bad.

NATALIE YAHR: It is. But PJ says we can’t really blame the bugs, that the emerald ash borer where it evolved in East Asia, it was living on trees that were mostly sick or dying already, but here in the U.S., it’s encountering trees that have no resistance to it.

PJ LIESCH: A lot of times humans like to put things in, you know, is it good or bad? And certainly it’s doing a lot of damage. But it’s doing what it’s kind of always done, but it’s dealing with different trees now. So it’s like a kid in a candy shop that isn’t chaperoned. I mean, they’re just going to run wild because our ash trees here haven’t evolved with it.

NATALIE YAHR: So what’s at stake here with these invasive beetles running wild? 

MAX WITYNSKI: I posed that question to one of the people charged with looking out for trees across the state.

SHAHLA WERNER: My name is Shahla Werner, and I’m the plant protection section chief at the Wisconsin Department of Agriculture, Trade and Consumer Protection. 

NATALIE YAHR: Known his friends as DATCP.

MAX WITYNSKI: Right. So I asked Shahla what Wisconsin stands to lose.

SHAHLA WERNER: Well, Wisconsin has a lot of ash. I mean, over 800 million ash trees are estimated in the state of Wisconsin, and it’s an important species, you know, timber-wise and used for other purposes, as well, like I know baseball bats and tool handles and ash cabinets. I mean, you can do lots with ash. So there’s a lot of ash and EAB attacks all species of ash that includes white ash, green ash, blue and black ash.

MAX WITYNSKI: In total, ash accounts for about 7 percent of Wisconsin’s trees. It’s really a huge number. 

SHAHLA WERNER: The sad part of the story is that emerald ash borer is a death sentence. I mean, for ash, it has killed millions of trees in the 35 states where it’s been found in our country, and it’s now in five Canadian provinces. So it blows through. It’s almost impossible to stop — to completely stop. And you’re getting, you know, millions of dead trees in that time. 

MAX WITYNSKI: And the ash borer has only taken 10 years to spread across almost the entire state of Wisconsin. For a long time, DATCP placed individual counties under quarantine, which means that firewood couldn’t be transported from counties where the beetle had been detected to counties where it had not been detected. Last year, though, they opted to switch to a statewide quarantine, since EAB has been detected in 52 out of Wisconsin’s 72 counties. So the agency has acknowledged that the beetle is likely to continue spreading in Wisconsin, but they haven’t given up on it completely. There is still hope for a lot of ash trees, especially in urban areas, but that’s only if we take action.

NATALIE YAHR: Right. We talked with PJ about what would happen otherwise. 

PJ LIESCH: I mean, if we look at a kind of do-nothing scenario — we don’t try any type of treatments —  true ash trees almost guaranteed are going to die because of this insect.

MAX WITYNSKI: We also spoke with Jeff Olson, an arborist who lives in Oregon, Wisconsin. He told us that emerald ash borer adults can fly up to two miles in search of an ash tree to lay their eggs.

JEFF OLSON: If there is an ash tree, and the insect finds it, it’ll kill it. Very rare do you find a tree that doesn’t get infested with EAB. I don’t know how they find these trees that are kind of like on a farm out in the middle of the country, but the insect finds them.

NATALIE YAHR: And what can be done for these trees?

MAX WITYNSKI: Jeff, who makes a career out of taking care of trees, told us that the best treatment is emamectin benzoate. 

JEFF OLSON: It’s an insecticide that you inject into the tree. You drill a hole, and then you pump the insecticide right into the vascular system. It’s like an IV going into your body, and then the then the insect can die within 48 hours. Nothing will live if it’s feeding on a tree. 

MAX WITYNSKI: The treatment costs $12 per inch of the tree’s diameter. So bigger trees cost more, and it keeps protecting the tree for about two or three years before it needs to be applied again. So for a tree with a 20-inch diameter, you’re looking at about $240 every two or three years to treat. Customers can also choose to remove a tree, but that comes with costs top. 

JEFF OLSON: We did one in Shorewood, and it came out to — what was it? 40, 48 inches in diameter DBH [diameter at breast height]. But, when we looked at it to price the tree out to removal, it was going to be like $15,000. So the guy chose to treat it. You know, the cost came out to about $1,000 to treat it. But you know, $1,000 versus $15,000 to remove it, and you get to save the tree. 

MAX WITYNSKI: So, according to Jeff, if you’re looking to spend $15,000 on a tree to remove it, you could actually keep that tree alive for 30 to 45 years, instead just spending $1,000 every two to three years to do the treatment. But it’s not just homeowners who faced that choice. Thousands of ash trees are located, not on private property, but on city property, often in parks or the terrace between the sidewalk and the street. Cities, not homeowners, have the responsibility to either treat or remove those trees.

SHAHLA WERNER: You know, you see a lot of people they’re just like, well just cut down all your ash, and, sure, that’s one way to deal with it. But you have to realize, like, you’re losing then all the urban canopy in your city for an entire generation. It’s going to take like 40 years.

MAX WITYNSKI: Cities are responding differently based on their priorities and the resources they have available. Shahla told us that Milwaukee has decided to save a huge number of its ash trees.

SHAHLA WERNER: Milwaukee really would only remove an ash if it had a wound down its bowl or something like that, like they really tried to save — I think it’s over 20,000 ash trees. And, you know, all the mental and physical health benefits that urban canopy provides in the habitat for wildlife, like, I think that is really sensible. And there’s research from UW-Stevens Point that backs up, you know, tree care in an urban setting is always expensive. So like whether you cut them down, well, there’s that expense and then you have to replant with something. And then you have to maintain all those new trees like water them and do whatever other, you know, things you have to do in the growth of that tree. So it may sound cheaper to just cut down all your ash because you don’t want to treat them. But it also might be not really a savings over the long term, especially when you consider the benefits of those urban ash trees. 

MAX WITYNSKI: But there’s no question: Trying to save the trees would require a really long-term investment on the part of the city. 

SHAHLA WERNER: One caveat I would say about any policy like that is that you have to be able to make a case generally to politicians like your alders and your mayor, that that kind of treatment can never be let up. You can’t become complacent and, you know, someone with a poor understanding of the biology might say, “Well, good job, Milwaukee.” And it’s like, boy, if they quit treating, those trees are like sitting ducks once the chemical’s out of the system.

NATALIE YAHR: Researchers are also experimenting with bio controls using other animals to keep the emerald ash borer in check. In this case, we’re talking about tiny parasitic wasps. 

MAX WITYNSKI: How tiny?

NATALIE YAHR: PJ Liesch told us, if you saw them, you’d probably think they were gnats, that they’re not yellow and black and stingy.

PJ LIESCH: So essentially the the female wasp, she would inject her eggs into the host insect and again it’s either emerald ash borer larvae or eggs. The wasp egg is going to hatch, the wasp larvae is then going to consume emerald ash borer from the inside.

MAX WITYNSKI: Wow, that’s pretty amazing.

NATALIE YAHR: Yeah, it’s pretty creepy. He said it’s sort of like the old sci fi movies like “Alien” where the creature busts out from inside of somebody. But he said, as effective as the wasps are in controlling the emerald ash borer population, raising them as a labor-intensive process. So while they’re being released in some places, it’s probably just not practical on the large scale until researchers figure out better ways to raise the wasps

PJ LIESCH: In the grand scheme of things, I would say we’re still fairly early in the ballgame when it comes to bio control of this. We haven’t really quite figured out, you know, is there a critical  mass, you know the number of wasps we need to release before we start getting really good control of emerald ash borer. And we haven’t done that many releases in the grand scheme of things.

NATALIE YAHR: He says biological control methods can be slow, but they could potentially create a long-term balance in the ash borer population. It just might be decades or more from now.

MAX WITYNSKI: Before the emerald ash borer arrived in Madison, 22 percent of Madison street trees were ash — a little bit less than 22,000 trees. Marla Eddy, the city forester, told me that the city plans to treat about half of those trees. They’ve been removing and replacing the others over the last few years and plan to finish removals by the spring. So most of the city-owned ash trees still standing along Madison streets this summer will be in treatment for emerald ash borer.

NATALIE YAHR: We spoke with UW-Madison journalism professor Mike Wagner and his daughter Eleanor, who live near Madison’s Edgewood College. A city-owned ash tree in front of their family’s house was cut down this past summer, and Eleanor and her sister made the most of it. Can I ask you to tell me what we’re looking at here? 

ELEANOR: We painted the tree stump because they cut it down, and we thought it looked like a heart. And so we painted it and put our handprints on it. 

NATALIE YAHR: Eleanor’s dad, Mike, told us they’d received notice from the city a few years ago that the tree was in danger of getting cut down due to emerald ash borer. But the fact that the beetle was partly responsible was news to Eleanor. Had you known about that bug? 

ELEANOR: No.

MIKE WAGNER: Have you seen some of the trees with the green plastic around them? 

ELEANOR: Mmm-hmm. 

MIKE WAGNER: Yeah, so some trees got treated for it. Ours didn’t. 

MAX WITYNSKI: In parks, the city marks the trees that are going to be treated with a green ribbon. Trees that are going to be removed receive a yellow spray-painted dot.

NATALIE YAHR: For Mike Wagner, the trees are an important part of the home where his family has lived for years. How long have you lived in this house?

MIKE WAGNER: Eight years? Yeah. Is that right?

ELEANOR: Seven.

MIKE WAGNER: Seven and a half, I guess. Yeah. Seven and a half. 

ELEANOR: Yeah, that’s not eight.

MIKE WAGNER: One of the things that was attractive about the neighborhood to us is just how old it is. And we like old houses, and old houses often come with lots of old trees. And so the neighborhood is really pretty, especially in the summer and fall with kind of a canopy of leaves and all of that. And so we haven’t lost that 100 percent or anything, but certainly it’s different now that some of the trees are gone.

MAX WITYNSKI: We also spoke with someone who’s seen this sort of thing play out before.

NATALIE YAHR: Yeah, we met up with Jeannine Desautels, who’s 79, a retired nurse and has lived in her house in the Regent neighborhood for 50 years.

MAX WITYNSKI: She had us over to her house where we had tea and cookies, met her dog, Sophia, and canary, Tweetie.

NATALIE YAHR: Yeah, it was lovely. This isn’t the first tree plague she’s seen play out right outside her front door.

JEANNINE DESAUTELS: When I first moved here, of course, we had elms. And I had three elms, one on the other side of the driveway and two on the terrace.

NATALIE YAHR: Of course, just as Jeannine and her husband were moving into their new home in 1969, Dutch elm disease was sweeping the country. The fungus, which is spread by bark beetles, is fatal to mature American elms. It eventually killed most of the mature elm trees in America cities, and many of those were these large majestical trees. 

JEANNINE DESAUTELS: When they cut the elms down, they replaced it with one ash. But the canopy that we had is gone. I mean, really we had a beautiful canopy. That was one of the things that attracted me to this neighborhood, when we first drove in, was the canopy. It was just beautiful coming from Regent Street all the way down. That’s not there anymore.

MAX WITYNSKI: Most of the trees were replaced with ash and the new canopy grew up, though it wasn’t as impressive. Now, Jeannine’s worried about whether the emerald ash borer will take out those trees too.

NATALIE YAHR: Yeah, nearly all the trees on her street are ash, and she knows if the city replaces those trees with new ones, it’ll be a big change.

JEANNINE DESAUTELS: Then when you look at a new development, if there are very few trees in that development or the trees every young, it gives you a different atmosphere than a neighborhood where you have a lot of mature trees. I think mature trees are a lot more welcoming. They’re a lot better for the environment, and I think families would prefer to have nice mature trees in the yard for the kids.

NATALIE YAHR: So what’s the long-term solution?

MAX WITYNSKI: Homeowners have the opportunity to treat trees and private property, but they need to act quickly. If you’ve got an ash tree in an area where the beetle has been detected, and you haven’t started treating it yet, Jeff Olson says the decision point may have already passed.

JEFF OLSON: No, I think at this point in Wisconsin, it’s too late to treat. You know, there’s a lot of people that would say, like, “Hey, I just think my tree is sick. I want to do anything to take care of it.” But it’s just not wise to do it. Some people will just do anything to keep it alive. But you’re going to have issues with the tree being compromised and weak and going to fail. It becomes a liability.

NATALIE YAHR: Looking back on past tree plagues, it’s hard not to think that the next one could be right around the corner. After all, the emerald ash borer is thought to have arrived in the wood packing material of a shipping crate

JEFF OLSON: To control the stuff that comes in our country, you’d have to cut out all your exports. 

MAX WITYNSKI: It’s a tricky issue, but Shahla offered one suggestion.

SHAHLA WERNER: Should we consider, as a global community, at least banning something like solid wood packing material, which, you know, federal inspectors are always out there trying to inspect things at the ports as they come in. But the reality is there’s so much stuff coming in. You just can’t inspect most of it. Yeah, it’s a needle in a haystack. 

NATALIE YAHR: We might not always be able to stop invasive species at the port. But there was one solution that nearly everyone we talked with pointed to to make the next disease less devastating: planting a wider variety of trees. Here’s PJ Liesch again. 

PJ LIESCH: Urban foresters have really caught on to this and they’ve seen Dutch elm disease. Before that. we had seen chestnut blight. Now we’re dealing with emerald ash borer. And so I think folks have really realized that having diversity in the urban forest is really important. That way, if something comes in, instead of taking out 10 percent, or perhaps even more of your urban forest, it’s taking out a much smaller slice of the pie. It’s going to have much less of a noticeable impact in the grand scheme of things. So I’ve seen a lot of urban areas that are really emphasizing diversity when they’re removing trees and putting in new ones. I think that’s going to be really, really helpful in the long run so that when something else comes in, we’ll have that diversity in there, and the impacts will be minimized because of that.

MAX WITYNSKI: That would mean that the next time there’s a pest or disease wiping out trees, it might affect only a couple trees on a block. For now, though, he says that we haven’t seen the worst of the emerald ash borer.

PJ LIESCH: Really though this is going to be something we’re going to be watching play out, not just for years to come, but really for decades to come. And the reason I say that, if you look at a map of Wisconsin, in terms of where we have detections. And Department of Ag[riculture] has a map on their website, where it shows basically borders of municipalities where emerald ash borer has been confirmed. I mean, southeastern Wisconsin, it’s all shaded in because we have a very well-established infestation there. Dane County and southwestern Wisconsin, as well, it shaded in. When you look at most of the map, though, especially northern Wisconsin, it’s very sparsely shaded in and, at the moment, we’ve got about 50 counties with confirmed detections. That still means there’s about 20 or so counties in northern Wisconsin where emerald ash borer hasn’t been detected yet. So when I look at that map, I would say about three quarters of the state has not yet seen emerald ash borer. So that tells me that this is going to get a lot worse before it gets better.

MAX WITYNSKI: Though the emerald ash borer will likely keep spreading, it’s still important not to move firewood from one county to another. And Shahla Werner told us that, while millions of trees are likely to die, the fate of North America’s ash trees hasn’t yet been sealed.

SHAHLA WERNER: I would hope that, you know, there is some level of ash left. I mean, to lose a whole genus of trees — and especially one that’s so prevalent in Wisconsin — would just be devastating. So my hope is that there will be some regeneration and long-term survival and even looking, you know, thousands of years into the future, maybe our own ash will develop some resistance to the pest. I mean, so that’s not in my lifespan or yours even. But it’s still my hope that the science will continue to advance. I mean, if you look at other invasive pests, such as gypsy moths, you know, we’re still flowing the spread of that insect from east to west, and it’s only made its way about two thirds of the way across Wisconsin. So there are examples of developing pheromones and chemical controls that are highly specific to that pest that aren’t going to hit a bunch of beneficial non-target insects that are great. So just continuing to invest in science will be a way to preserve ash at least at some level across our landscape in the United States. 

NATALIE YAHR: This show was produced by us, Max Witynski and Natalie Yahr and Kathryn Wisniewski, with editing help from Stacy Forster and recording support from Laura Gutknecht and Dave Black of WSUM radio. If you’d like to learn more about the local and state plans regarding the emerald ash borer, or what you can do to help slow the spread, or if you want to see photos of this beetle and the damage it can do, visit curbonline.com.

MAX WITYNSKI: For Curb Magazine, I’m Max Witynski. 

NATALIE YAHR: And I’m Natalie Yahr. Thanks for listening.