Science's Battle Against Superweeds
For decades, farmers fought weeds with familiar chemicals. Now, science is forging new weapons in a battle against rising resistance.
Increase in herbicide-resistant weeds since the 1980s
Potential reduction in crop yields due to weed competition
Herbicide resistance is a classic example of natural selection in action. When a farmer repeatedly uses the same herbicide, any weed with a random genetic mutation that allows it to survive will thrive and reproduce, passing that resistant trait to its offspring 8 . Over time, the field becomes dominated by weeds that the herbicide can no longer kill.
The consequence is that many of our most important herbicides are losing their effectiveness. Weeds like ryegrass and pigweed have evolved resistance to multiple herbicide groups, leaving farmers with few options and threatening productivity 5 7 .
After a long wait, the pipeline of innovation is beginning to flow again. Researchers are now leveraging modern scientific tools to design solutions with precision.
First new generation of ACCase-inhibitor herbicides in nearly two decades. Controls grass weeds resistant to older herbicides like glyphosate and clethodim 6 .
| Product Name | Company | Key Feature | Target Crops |
|---|---|---|---|
| Metproxybicyclone (Expected 2026) | Syngenta | New generation ACCase inhibitor; controls resistant grasses | Soybeans, Cotton 6 |
| Keenali (Pending) | FMC | Contains tetflupyrolimet, a new Group 28 mode of action | Rice 1 |
| Cyclopyrimorate (Launched) | Mitsui Chemicals | First new mode of action since the 1980s; inhibits plastoquinone production | Rice 5 |
| Kyber Pro | Corteva | PRE herbicide mix (Groups 14, 5, 15) for broad-spectrum control | Soybeans 1 |
| Resicore REV | Corteva | Reformulated with encapsulated acetochlor for improved crop safety | Field Corn 1 |
While discovering brand new modes of action is critical, scientists are also finding clever ways to extend the life and utility of existing herbicides.
A key area of research is reducing the volatility, or tendency to drift, of older herbicides like dicamba, which has been used for over 50 years. Dicamba is a potent weed killer, but its off-target drift can damage neighboring crops 3 .
In an innovative study, researchers from The University of Western Australia and Curtin University found that by adding carbohydrates to dicamba, they could create a "pro-herbicide" that significantly reduces its volatility. These environmentally benign molecules change the herbicide's molecular structure without compromising its weed-killing power, making it a more neighbor-friendly tool for future weed management 3 .
Stable Application
Plant Absorption
Activation in Weed
The search for new herbicide targets is a complex process that borrows heavily from modern pharmaceutical research.
Vast collections of molecules, each tagged with a unique DNA "barcode," allow researchers to screen millions of potential herbicidal compounds against a target enzyme incredibly quickly 5 .
Researchers identify enzymes that are essential for plant survival, such as dihydrofolate reductase—a enzyme targeted in cancer therapy but unexploited by commercial herbicides 3 .
Companies like FMC still screen tens of thousands of molecules on plant material each year. When a promising "lead" compound is found, chemists create thousands of analogs 5 .
Collected from farm fields, these seeds are used in bioassays to confirm resistance and test the effectiveness of new herbicide candidates against real-world problems 7 .
To understand how this research works in practice, let's look at the experiment aimed at reducing dicamba's volatility.
Researchers hypothesized that by chemically modifying dicamba through conjugation with a carbohydrate, they could create a new compound with equivalent herbicidal activity but significantly lower volatility.
The team synthesized a new molecule by coupling dicamba to a glucose sugar. They then designed a step-by-step experiment comparing herbicidal activity, volatility, and conversion rates.
The carbohydrate-conjugated dicamba successfully reduced volatility while still enabling control of weed growth. The "pro-herbicide" is applied in its stable form and activated within the plant 3 .
The fight against herbicide-resistant weeds cannot be won by chemistry alone. The historical overreliance on a single tool is what caused the resistance problem in the first place 5 8 .
The scientific consensus is clear: farmers must adopt Integrated Weed Management (IWM). This means using new herbicides as part of a diverse toolkit 7 8 .
Disrupting the life cycle of weeds and varying the selection pressure makes it harder for resistance to evolve.
Suppressing weed emergence and managing the weed seedbank in the soil.
Applying pre-emergence herbicides to provide longer-lasting control and reduce reliance on post-emergence products 8 .
Sending weed seeds to diagnostic labs helps farmers understand which herbicides will still be effective on their land 7 .
The arrival of new herbicide targets and the reinvention of old ones mark a turning point in agricultural science. By pairing these powerful new tools with sustainable management practices, we can protect crop yields and work towards a future where farmers stay one step ahead of evolving weeds.