One day, about a decade ago, Seth Swoboda was mowing his lawn when he noticed something strange. He looked up at this big black oak tree and saw that the canopy was thin and the leaves were all curled and contorted.
“The tree looked like it was starting to die,” Seth said.
Then he looked around and saw those contorted leaves on some of his other trees too. By then, though, it was already too late. The trees would mysteriously die.
What was happening at Seth’s place in rural Illinois was happening all over the state and the Midwest.
Seth asked his neighbor, a biologist, what could possibly be killing his trees. And his neighbor had a hunch. He thought herbicides were drifting from farmland onto Seth’s property and wreaking havoc. He just had to prove it.
Credits:
Host: Dan WanschuraProducer: Christian Elliott
Editing: Morgan Springer
Additional Editing: Dan Wanschura, Ellie Katz, Claire Keenan-Kurgan
Music: Blue Dot Sessions
This episode is based on a story Christian Elliott wrote for bioGraphic Magazine. Read it here.
Transcript:
DAN WANSCHURA, HOST: This is Points North. A podcast about the land, water and inhabitants of the Great Lakes. I’m Dan Wanschura. It’s the fourth of July, late morning, and it’s already hot. Seth Swoboda walks around his property outside of Nashville, Illinois. His front yard is speckled with shade from a handful of trees. It used to be a dense grove of oaks, but many of them have died.
SETH SWOBODA: You can see the one stump there actually. Big tree. But there was another great big oak, and then the further south you moved through here, the thicker the stand of trees.
WANSCHURA: Seth noticed the problem almost a decade ago.
SWOBODA: I was just mowing grass and … there was a big black oak … and I noticed the canopy was thin, and the tree looked like it was starting to die.
WANSCHURA: When he looked closer, things got even stranger. Leaves were growing into these curled, contorted shapes. And he saw the same symptoms on other oaks all over his property. It was like they were all sick.
SWOBODA: By the time I noticed it, it was already… too late really. I mean they were- they went fast.
WANSCHURA: Before long, those big beautiful oaks died. Seth was perplexed. But he had someone in mind who might have answers: Marty Kemper, his neighbor, who’s also a retired biologist for the state of Illinois.
SWOBODA: I just knocked—I cold-called him.
MARTY KEMPER: He came over and dumped on me!
WANSCHURA: That’s Marty.
SWOBODA: Yeah, I knocked on his door, and I'm like, “Hey, is there some kind of oak disease going around here?” And he’s like, “Uh, I don’t know? Maybe, maybe not?”
WANSCHURA: Oaks are incredibly important. A single mature tree can support a couple thousand species of insects, birds and mammals. And oaks are known to be tough. Typically drought doesn’t hurt them and neither does disease. So something killing them like this — that was both concerning and surprising.
KEMPER: The fact that they’re declining in health and some are dying is amazing because you know … they’re survivors. They have to be. They’re exposed to things for decades or hundreds of years.
WANSCHURA: So, considering all that, Marty didn’t think Seth’s oaks had a disease. But he did have a perpetrator in mind. A perpetrator that is kind of dangerous to accuse in a state dominated by agriculture: Herbicides. Chemicals used to kill weeds. At least, that was Marty’s theory. Now, he had to prove it, and see if he could save the trees – both here on Seth’s farm and across the state – before it was too late. Producer Christian Elliott has the story.
CHRISTIAN ELLIOTT, BYLINE: On this particular day, Marty and Seth are checking on the oaks. Seth points them out.
SWOBODA: Yeah these are our sample trees. … Yeah, one, two and three. Right here, these three.
ELLIOTT: Every year since 2017, Marty’s come here to check for symptoms like leaf cupping and curling, and to take leaf samples.
KEMPER: We take leaves from one, two, three, put them in a bag … send them off to the lab and find out what’s in them.
ELLIOTT: What’s in them? So far, almost all of Seth’s oak leaf samples have come back positive for a number of herbicides, and more than fifty other plant species on his property have shown visual signs of herbicide damage. Herbicide drift wasn’t always a problem here. Seth’s little piece of wooded pasture in central Illinois has been surrounded by corn and soybean fields on all four sides for the entire time this property’s been in Seth’s family – four generations.
SWOBODA: I’m 45 years old, my grandparents lived here before me. I grew up out in this whole area.
ELLIOTT: So farming isn’t new here, but the way that farming is done has changed dramatically in just the last couple of decades.
SWOBODA: My dad would say, “Well, for weed control, we’d take a tractor, and we’d cultivate.”
ELLIOTT: Cultivating. That’s how all farmers controlled weeds – by plowing them under. That changed around the 1950s. Herbicides hit the market. Now, instead of cultivating, farmers sprayed chemicals to kill weeds. The herbicide of choice for decades was glyphosate, also called RoundUp. Over the decades, farmers sprayed more and more of the stuff, using bigger and bigger farm equipment. But in the early 2010s, they ran into a problem: weeds started to evolve resistance to glyphosate.
SWOBODA: We went from glyphosate is the go-to, be-all, end-all for all weed control for farmers.
ELLIOTT: To glyphosate no longer working. The chemical industry scrambled for a solution and found one: older herbicides like 2,4-D and dicamba.
SWOBODA: The use of it just ramped up, and big time.
ELLIOTT: These two herbicides, 2,4-D and dicamba, they’re highly volatile, meaning they can easily transform from liquid to gas. And it happens when the temperature outside is hot.
ERNDT-PITCHER: Those chemicals can evaporate from the plant and soil surfaces and move long distances in the atmosphere.
ELLIOTT: That’s Kim Erndt-Pitcher, who works closely with Marty. She’s an ecotoxicologist for Prairie Rivers Network, an Illinois nonprofit. That’s the organization that’s taking Seth’s samples and sending them for testing. Kim says once these chemicals are in the atmosphere, they can come down as rain, miles from where they’re sprayed. And that can happen even when farmers follow the rules.
SWOBODA: It’s the nature of the chemical; it’s what it does. They can do everything according to the label and apply it correctly. It still doesn’t stay where it’s intended to be. That’s my complaint.
ELLIOTT: Around when Seth first asked Marty what was up with his trees, Kim had started getting calls from people across central and southern Illinois noticing the same symptoms. So, to show me the full scope of the problem, we hop in the car.
ERNDT-PITCHER: I have boys, so there’s always random tools.
ELLIOT: Sure.ERNDT-PITCHER: And extra pairs of shoes. Let me close out trunk here.
ELLIOTT: And Marty and Kim take me on a whirlwind tour of some of the sites they monitor for herbicide drift damage. Their organization, Prairie Rivers Network, has nearly 300 monitoring sites across the state.
ERNDT-PITCHER: Alright, can we turn that AC on max please.
ELLIOTT: Sorry, I think I turned it off.
KEMPER: No, I thought maybe the right response here is just turn the AC off and turn the windows down and acclimate.
ERNDT-PITCHER: No, no.
KEMPER: Are you sure?
ERNDT-PITCHER: I’m positive, Marty.
KEMPER: I vote for windows down and acclimate.
ERNDT-PITCHER: I don’t.
ELLIOTT: After a bit more good-natured bickering and a debate over stopping at Dairy Queen for ice cream, we reach Eldon Hazlet State Recreation Area and walk up to a cherrybark oak.
KEMPER: The thing I can’t show you is what normal leaves look like, okay, because there’s not one single normal leaf on this tree.
ELLIOTT: I see they’re all kind of cupped or curled a little bit.
KEMPER: We have stunting. This leaf is probably one fifth- one sixth the size it should be, … and you have puckering on the surface.
ELLIOTT: These are all typical symptoms of an oak poisoned by herbicides. And they’re unique to this class of volatile herbicides: dicamba and 2-4,D. Here’s how these herbicides mess a plant up. They mimic a key growth hormone. That hormone drives a plant’s leaves to grow out of control into these strange shapes. But eventually the plant runs out of resources and dies. That kills small weeds. It tries to do the same thing to oaks.
KEMPER: Basically, this is a mess. This is a trainwreck for oak foliage.
ELLIOTT: Big oaks, they don’t die outright from one drift incident. But distorted leaves can’t produce food for trees as well as normal ones can. The trees start to struggle.
KEMPER: The trees are telling us that. They’re telling us very plainly.
ELLIOTT: And herbicide drift isn’t happening in a vacuum. This is one more stressor, on top of many stressors that native ecosystems already deal with: things like climate change, extreme weather and disease. And for trees that are already stressed, it’s enough to kill them.
ELLIOTT: We stop at a handful of other places throughout the afternoon. Marty pulls over again and again to point out symptoms on different species of trees – so often the ride gets pretty jerky.
ERNDT-PITCHER: Marty, I’m starting to get carsick.
KEMPER: You’re getting carsick?
ERNDT-PITCHER: Because you’re stopping and going.
KEMPER: Oh, I’m sorry!
ELLIOTT: She jokes she’ll get him a pointer stick for Christmas. We drive through downtown Nashville, Illinois with kids gathering for a parade outside these brick Victorian houses lined by redbud trees that also have herbicide damage. We go through a campground full of barbeques under the thinnest oak canopy I’ve ever seen. At one point, we pass a sprayer working the fields on the holiday.
ERNDT-PITCHER: There you go.
ELLIOTT: They’re spraying right now.
ERNDT-PITCHER: They’re spraying right now. And what’s the temperature?
ELLIOTT: 91?
ELLIOTT: Definitely hot enough for 2,4-D and dicamba to evaporate and drift. Before Marty and Kim started looking, no one was monitoring for herbicide drift damage in Illinois. By 2024, their organization Prairie Rivers Network had enough samples to publish a report. They found that 90% of plant leaf tissue samples they collected had herbicides – that’s oaks, other trees like hickory, ash, and flowers and other plants. That report got the attention of the Illinois Natural History Survey, which conducted its own study across 200 additional sites and found the largely same damage. So it’s safe to say drift is happening, and it’s hurting plants. We don’t know exactly what this means – if drift damage, year after year, means a tree will definitely die. Scientists are studying that now. But we do know drift is widespread, and trees are dying where they weren’t before. And it’s not just in Illinois.
ERNDT-PITCHER: Foresters in Kentucky are worried about this, in Nebraska, and Missouri.
ELLIOTT: I talked to landowners in Iowa who have drift damage, and agriculture departments in Minnesota, Wisconsin and Michigan are noticing drift too, just to a lesser extent. Anywhere there’s agriculture that relies on volatile herbicides, you can bet drift is happening, even if it hasn’t been documented yet. Tracking the damage in Illinois, it takes a toll on these two. Marty grew up here. At one site we visit, Washington County Conservation Area, Marty tells me he’s been coming since he was 10. We walk out onto a little peninsula overlooking a lake. Above us, you can see the completely dead canopies of a stand of oaks.
KEMPER: This was a fantastic white oak beautiful canopy, and it’s a disaster. It’s a forest disaster in this little area right in here.
ELLIOTT: You said you’ve been coming here since you were a kid. I mean, people connect with trees on an emotional level. What does it feel like to be here now when it’s like this?
KEMPER: Well, it’s actually- I’m a biologist too, and it’s scary. … We’re seeing a gradual decline in the health of the forest. And the chance that this doesn’t have ecological cascades in my estimation are zero.
ELLIOTT: Kim’s the same way. When I called her up before our field trip, she told me…
ERNDT-PITCHER: It will change how you look at everything around you … Be prepared for that … You start to see it everywhere you go … It takes a toll on you, mentally.
ELLIOTT: She worries about a time when the Midwest’s mighty oaks are gone. So the obvious question: what can be done about it? Marty and Kim and other nonprofits across the country have documented this is a problem. They’ve proved it with meticulous research over years.
ERNDT-PITCHER: So I don’t think there’s any doubt herbicides are causing this problem. It’s just how are we going to fix it.
ELLIOTT: That’s coming up after the break.
(Points North Fan Club message)
ELLIOTT: To find out how we might fix it, we’re making one last stop. At the end of a long day, Kim and I bounce around in the bed of Marty’s truck, riding across a pasture on another farmer’s property.
ERNDT-PITCHER: Most reporters we take out are exhausted by the end of our day.
ELLIOTT: Yeah, I’ve been hot.
ERNDT-PITCHER: I’m sorry.
ELLIOTT: We’re driving to see a state record tree. It’s a post oak, the largest in Illinois. Kim tells me she’s taken state officials and lawmakers here to try to convince them to act.
ERNDT-PITCHER: I mean, this is one of our state champions. … It’s a legacy. It’s a big deal, and it’s an incredible tree, and it’s sad to see it decline like this year after year.
ELLIOTT 17:50: Yeah, what have been the reactions? You take these leadership people here to see this tree. Does it have the effect that you hope?
ERNDT-PITCHER: Well, my hope is that action will be taken, right?
ELLIOTT: Action like legislation. Nothing has passed yet, but one bill working its way through the Illinois statehouse right now would require herbicide applicators to warn nearby schools and parks before spraying. But besides legislative action, their other option is the Illinois Department of Agriculture, the IDOA. The IDOA doesn’t actively monitor for herbicide drift damage, but it does investigate complaints. Most ag departments in Great Lakes states do too. Seth has gone down that route. But it was too hard to prove.
SWOBODA: If they had a field of soybeans, and I somehow killed those beans, I would sure hear about it, right? So here we have the herbicide drift trespasses onto private and public land, damages the native species, plants and everything. … There’s just no recourse for it.
ELLIOTT: Ag officials in Illinois declined a phone interview, but in an email statement they acknowledge that drift happens. They say they make sure the chemicals are used properly. Kim says if the state doesn’t take action, if laws don’t change, if our agricultural system doesn’t change, this isn’t going to get better. Dicamba, one of those volatile herbicides, was actually banned during last year’s growing season. But the Trump administration’s EPA just re-approved it. So it’ll likely be back this spring. That means more drift, more dead trees.
ERNDT-PITCHER: This is unfair. This is people’s personal property rights. … We have all these people asking us … how are they going to get compensated for the trees that they have to take down or the backyard gardens that they can’t eat or the fact that they have to close their windows because they’re smelling pesti- we hear these complaints all the time. … This is their right to a healthful, clean environment. It’s being violated on a regular basis year after year, and nobody’s doing enough about it. … This industry is incredibly powerful and influential. And I think if more people knew what all this meant, what we're risking by inaction, they would be really mad. Like, really, really mad."
ELLIOT: Finally, we arrive at the post oak.
ERNDT-PITCHER: Whew, that was really warm.
ELLIOTT: That is a pretty amazing tree.
ERNDT-PITCHER: It is magnificent.
ELLIOTT: The largest post oak in Illinois is centuries old. It’s up on a hill overlooking a pond. But the canopy’s a little thin, and some branches are dying. Marty points to piles of dead trees, damaged by herbicides, surrounding the post oak.
KEMPER: You see that pile there? There’s a pile down there, there’s a pile over there.
ELLIOTT: About 15 trees have died all around this oak since they started studying drift.
KEMPER: On the positive side, the state record post oak, which is by far the oldest tree here, is hanging in there.
ELLIOTT: Yeah.
