Farmers use weed-killing herbicides on nearly all major crops grown in the U.S., but over time, weeds have evolved resistance to these products. According to a cover story in Chemical & Engineering News, an independent news outlet of the American Chemical Society, there hasn’t been an herbicide with a new weed-killing mechanism introduced in decades, but chemical companies have started using new tools to aid their search.
Crop protection companies had been cranking out new herbicides for decades, but new discovery slowed to a halt in the 1980s, writes Associate Editor Matt Blois. The drought was not for lack of potential targets; instead, experts blame the introduction of genetically modified “Roundup Ready” crops resistant to glyphosate, increased regulatory costs and industry consolidation. In the meantime, weeds evolved resistance to the few modes of action, or mechanisms, that were targeted by existing herbicides.
To address this challenge, companies are now starting to shift their research focus. Typically, researchers conduct large screens, narrowing the field to thousands of molecules that they test on plants, but recently some companies have begun investigating the mode of action earlier in the discovery process. And other tools — often inspired by the pharmaceutical industry — could help speed up this time-consuming and costly process. Artificial intelligence, X-ray crystallography and computer simulations can help researchers better predict which plant enzymes could be good targets and which herbicides could inhibit them. With DNA-encoded libraries, researchers can quickly identify which of billions of compounds bind to a particular plant enzyme. These techniques are beginning to result in new commercial products, but some experts remain cautious. They advise farmers to moderate the use of new products and consider adding other crop protection tools to their arsenals to curb further evolution of herbicide resistance and to protect the future of farming.
The article is available at https://cenm.ag/crop-protection.
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Chemical & Engineering News
Following several fallow decades, herbicide companies are searching for new modes of action
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