The next generation of weed control has officially arrived, but for many U.S. row-crop farmers, the tools remain just out of reach. They are often too expensive, too slow, or too impractical for widespread adoption on large-scale operations.
Kevin Bradley, University of Missouri Extension weed scientist, sees the dilemma clearly. He notes that conversations among his industry colleagues have fundamentally shifted away from the traditional playbook. Where scientists once focused almost exclusively on identifying specific weeds and matching them with the right chemistry solution, the industry is now forced to look beyond the jug.
“Our program has shifted from herbicides to looking at weird stuff that is not just a herbicide,” Bradley says. “And it is probably going to be a part of our future cropping systems.”
This “weird stuff” includes high-tech innovations like harvest-time seed destruction, electric zappers, and precision camera-based spot sprayers.
While some cultural tools — like cover crops — are already being deployed, some technologies are still years away from fitting into row-crop operations. But all share a common thread: they are non-chemical tools that Bradley and other scientists anticipate farmers will eventually stack on top of existing herbicide programs to slow the relentless march of herbicide-resistant weeds like waterhemp and Palmer amaranth (pigweed).
Cover Crops Lead The Pack
Among the emerging tools, Bradley says cover crops currently offer the most immediate payoff for farmers willing to adopt them.
“The quickest and easiest is cover crops,” Bradley says, though he acknowledges performance can vary widely by region.
According to Bradley, a cover crop needs two critical characteristics to successfully suppress weeds: high biomass and allelopathic (natural chemical) properties. Cereal rye delivers on both fronts, which explains why it has become the most widely adopted cover crop to date.
In the Midwest, high-biomass cereal rye frequently pulls double duty. It aggressively suppresses pigweed species while simultaneously drawing excess moisture out of heavy soils, allowing farmers to get into the field during wet springs. However, that same moisture consumption can quickly become a liability in arid regions.
“People in drier climates are saying, ‘We don’t need anything else sucking moisture out of the soil,’ so it is a geographically specific fit,” Bradley explains. “But where it works, we can get quite a bit of pigweed suppression out of our cover crops, for sure.”
Seed Destruction Works—For A Price
Another innovation Bradley’s team has tested extensively is harvest-time weed seed destruction systems. These systems often consist of heavy-duty impact mills mounted inside the combine to intercept, crush or burn weed seeds as the crop is harvested. This prevents viable weed seeds from returning to the soil and helps stop the spread of herbicide-resistant weeds
The data is promising. “We did some of the first work and found they are efficacious, even on very, very small weed seeds like the pigweeds,” Bradley says.
The hurdle isn’t the technology’s performance. For many farmers, it’s the economics.
“At a minimum of a $70,000 add-on to a combine that already costs a million dollars, we just haven’t seen U.S. farmers really adopt it yet,” he notes.
Bradley says that Australian and Canadian growers — many of whom face even worse herbicide resistance issues than the U.S. — have embraced seed terminators far more readily. When he presents the concept at U.S. grower meetings, enthusiasm runs high until the price tag drops.
“When I talk about it in a group of farmers, one of the last questions inevitably is, ‘How much is it?’ When I say the number, I can see their heads just go down, and they say, ‘Well, I don’t know about that,’” Bradley says.
Electric Weed Control: Proven, But Not Yet Practical
For the past five or six years, Bradley’s research program has invested heavily in evaluating electric weed control — high-voltage systems that electrocute tall weeds that have escaped earlier control methods and poked through the crop canopy.
Working with graduate students on proof-of-concept research, Bradley confirmed that the technology works, but field-to-field performance was inconsistent. Solving that puzzle yielded a surprising answer.
Researchers discovered that success depended less on the weed’s size and more on contact placement. Electrocution was far more consistent when the boom could be lowered between the rows to strike the weed lower, rather than simply skimming the top 2" or 3" of the plant.
One of the leading manufacturers of these systems, The Weed Zapper, operates out of Sedalia, Mo., just an hour away from Bradley’s home base in Columbia.
The company touts its Annihilator series as “a ruggedly built tractor attachment that instantly kills weeds through the root. With this farm equipment, you will be able to kill both in-row and between-row weeds.”
Bradley says the tool works well, but he is cautious about its implementation on commercial farms. “Just a year or two ago, it was a 40-foot implement that you had to operate at 2 or 3 mph. That combination of size and speed means most large-scale farmers simply aren’t going to do it,” he notes.
For now, Bradley sees electrocution fitting best in organic systems, specialty crops or on smaller-acreage operations.
“We need the smart engineering people to integrate this into a robot or an autonomous platform,” he says. “I feel like this will be a part of our future, but I don’t think it’s ready for a 1,000- to 5,000-acre farmer just yet.”
Spot Sprayers Can’t Replace Residuals
Camera-based, artificial intelligence-driven “spot-spray” systems are also gaining traction in the U.S., but Bradley warns against viewing them as a silver bullet. In his view, precision systems cannot replace the foundational benefits of a broadcast preemergence herbicide — at least not in the intense weed pressure of the lower Midwest and mid-South.
“We have to have a broadcast, full-out pre-emerge,” he emphasizes. “In Missouri, our soil seedbank populations of waterhemp are just too high to do anything other than [starting with] a blanket pre-emergence residual.”
That doesn’t mean smart sprayers lack sufficient value. Bradley envisions them playing a vital role in post-emergence programs, allowing farmers to clean up escapes while drastically reducing overall herbicide volumes.
“Can we come back with some spot-spray technology post-emergence? Sure, I think that can be a part of our future, and the EPA really likes that approach,” Bradley says. “But we absolutely must start with a blanket residual.”
Tillage and Old Tools Make a Comeback
Interestingly, Bradley says the hunt for non-chemical solutions to weeds is also driving a resurgence in old-school mechanical tactics. Farmers are dusting off traditional tillage equipment and exploring post-harvest weed-seed management.
In some dryland systems, growers are even putting sweep plows back to work to manage tough, resistant grasses in what were previously continuous no-till programs.
Meanwhile, interest is growing in post-harvest strategies that concentrate and destroy weed seed, such as narrow-windrow chaff burning or letting chaff rot in designated lines. While U.S. adoption still lags behind global counterparts, Bradley expects these practices to gain ground as weed-resistance pressure intensifies.
An Arms Race The Weeds Are Winning
Ultimately, Bradley believes farmers must stop looking for a single, permanent fix. Weeds are highly adaptable, and they will eventually evolve to evade mechanical and cultural tactics just as they did with chemistry.
It is already happening in Australia, where decades of strict harvest weed-seed control have caused certain weed species to adapt their biology, dropping their seeds earlier in the season before the combine can harvest them.
“If you use something long enough over a vast number of acres, the plants will adapt,” Bradley warns. “With regard to the seed terminators, there are already plants changing their seed production habits. There’s no reason to believe that electrocution wouldn’t trigger the exact same response.”
The struggle to rein-in weeds will continue to be a battle for row-crop farmers. Because weeds inevitably find a way around any single tactic, Bradley says the future of successful row-crop farming will depend on a multi-faceted approach: continuously rotating, stacking, and balancing cultural, mechanical and chemical strategies.
You can hear more about Bradley’s research on this latest episode of The Crop Science Podcast Show.
