When it comes to controlling invasive, herbicide-resistant weeds, farmers might be losing the battle

Kochia is also known as burning bush, Mexican firebrush,
mock cypress or tumbleweed. (Cornell photo)

Viruses and bacteria aren't the only things that can develop science-challenging resistances; weeds can also genetically modify to subvert herbicides and spread. "Crop-killing weeds such as kochia are advancing across the U.S. northern plains and Midwest, in the latest sign that weeds are developing resistance to chemicals faster than companies can develop new ones to fight them," report Rod Nickel and Tom Polansek of Reuters. "In many cases, weeds are developing resistance against multiple herbicides, scientists said."

When uncontrolled by herbicides, noxious weeds multiply so quickly that the intended crop gets choked out. Nickel and Polansek write, "Reuters interviewed two dozen farmers, scientists, weed specialists and company executives and reviewed eight academic papers published since 2021 which described how kochia, waterhemp, giant ragweed and other weeds are squeezing out crops in North Dakota, Iowa, Wisconsin and Minnesota as chemicals lose their effectiveness."

While weeds are always part of farming, prolific herbicide-resistant weeds kill crops. Farmers "say their losing battle with weeds threatens grain and oilseed harvests at a time when growers are grappling with inflation and extreme weather linked to climate change," Reuters reports. "Kochia, which spreads as many as 30,000 seeds per plant, can cut yields by up to 70% if left unchecked, according to Take Action, a farmer resource program of the United Soybean Board."

Herbicide development takes years, and many "candidates" fail to make the cut. "FMC plans the 2026 launch of an herbicide to kill grassy weeds in rice crops based on the industry's first new mode of action, a term for how a chemical kills a weed, in three decades," Nickel and Polansek explain. "The herbicide was in development for 11 years. . . . The world's biggest agriculture chemical and seed company, Germany's Bayer, hopes to produce its first new mode of action herbicide in over 30 years by 2028."

There is another answer to the problem. Reuters reports, "Bill Freese, scientific director of the Center for Food Safety in Washington, said farmers should shift away from crops genetically engineered to tolerate herbicides, which lead to plants becoming resistant to multiple chemicals through repeated sprayings. 'It's like this toxic spiral,' Freese said. 'There's no end in sight.'"