Soybean Farmers May Need to Think Beyond Herbicides
University of Missouri state extension weed scientist Kevin Bradley has a blunt and urgent message for soybean growers.
“Resistant weeds are our biggest problem,” Bradley says. “And unfortunately, it’s not getting any better — and that’s what’s really concerning.”
Bradley has spent the past 22 years studying weed management strategies for Missouri row crops. He says that for too long, the system has relied almost exclusively on herbicides. But with resistance growing and chemical costs rising, that strategy is failing.
“We are just so herbicide-centric in U.S. agriculture,” he says. “It was simple, it was easy, and it was cost-efficient. I’m not sure that that is true about any one of those three statements anymore.”
Integrated Weed Management in Action
Bradley is now focused on integrated weed management (IWM) — a long-term, diversified approach that blends multiple tactics to control weeds more sustainably.
“Nothing wrong with herbicides; that’s the way U.S. agriculture is focused,” he says. “But it just isn’t working. It’s not sustainable. We continue to get herbicide resistance after herbicide resistance and unfortunately we just keep running out of our limited herbicide options.”
His research includes everything from cover crops to drones to combine-attached seed destruction devices. Bradley has even evaluated the Weed Zapper, or weed electrocution — not as a silver bullet, but as one more tool in the toolbox.
“Electrocution falls into that category of, could this be another thing someday?” he says. “Mostly it’s just, ‘okay, it’s August or July, and all efforts have been exhausted and some of them are in vain, and I still have waterhemp sticking up above the soybean canopy’ Could electrocution solve that problem? And the answer is yes, it can.”
Bradley and his team are also tracking how and when to deploy these newer technologies, but cost remains a barrier.
“There are some smaller start up companies that offer services deploying robots for targeted weed management or weed management between the rows,” he says. “But we haven’t had a lot of wide-scale acceptance or adoption to any of those kinds of things yet… it’s either viewed as far-fetched on cost prohibitive. But with current costs of our seed traits and chemicals, I’m not so sure that’s true anymore.”
Looking for New Traits — and Not Finding Them
On the genetic side, Bradley says the outlook isn’t much brighter.
“There’s really not a lot that I know about on the horizon that I can get very excited about. We have some new traits that we are told will be coming out with five different types of herbicide resistance,” he says. “The problem is, we’re already seeing pigweed populations that have resistance to each of these 5 classes of herbicides.”
For now, his team continues screening for resistance, collecting seed and evaluating weed populations. But breakthroughs in soybean seed traits are still elusive.
“We are continuing to screen Missouri waterhemp populations to the herbicides our growers are most commonly using for the control of this species. My hope is that this will help everyone to see the extent of the problem,” he says.
Listening to Farmers, Searching for Solutions
While the path forward is murky, Bradley isn’t giving up. He still encourages new ideas and feedback from growers, and he hears from them often.
“Part of my life and job is interacting with farmers on a daily basis,” he says. “Certainly through field days and farm shows and events and all of that, but also just day in and day out — answering questions through phone calls, emails, texts, going to problem fields, all that kind of stuff.”
Bradley is a strong proponent of keeping weed seed from returning to the soil, even if that means late-season rescue efforts.
“If we can keep any weed from returning seed back to the soil, that is a huge win,” he says. “Targeted weed removal — whether it’s with herbicides, fire, laser, electrocution, tillage — that’s going to be a huge part of our future.”
Upcoming Field Day
Bradley and other Mizzou researchers will share the latest on weed, pest, and crop management at the MU Crop and Pest Management Field Day on July 10 at the Bradford Research Farm near Columbia.
“It’s one of our biggest educational efforts,” Bradley says. “Our state extension specialists including plant pathologists, entomologists, agronomists — they all are involved in this event and are giving talks and recommendations and showing what we are working on here.”
Registration is open and will continue through the day of the event, but participants are encouraged to sign up in advance to help organizers with planning. For details and to register, visit https://extension.missouri.edu/events/2025-crop-and-pest-management-field-day
This article is funded in part by the United Soybean Board.