As weeds overcome existing technologies on the market and build resistance to them, herbicide manufacturers are researching new ways to stop their progress. One method companies are using is formulating and packaging a combination of active ingredients and sites of action. That’s a strategy Syngenta is employing with its new Acuron GT premix herbicide for use in corn.
The herbicide offers four active ingredients – bicyclophyrone (Group 27), mesotrione (Group 27), s-metolachlor (Group 15) and glyphosate (Group 9).
The herbicide works through three sites of action, offering a fortified front against broadleaf weeds and some grasses:
• Bicyclophyrone and mesotrione are HPPD inhibitors, often referred to as “bleacher” herbicides.
• S-metolachlor works by inhibiting the synthesis of long-chain fatty acids.
• Glyphosate inhibits a plant enzyme (EPSP) that plays a role in the synthesis of three amino acids – phenylalanine, tyrosine, and tryptophan.
Acuron GT averages greater than 90% postemergence control on large-seeded broadleaves and small-seeded broadleaves, according to Ryan Lins, research and development scientist for Syngenta, based in Minnesota. In some scenarios, the herbicide approaches 99% postemergence control.
“In particular, its higher-level control of large-seeded broadleaves such as giant ragweed, morningglory and cocklebur, and pigweed species like Palmer amaranth and waterhemp, really sets Acuron GT apart from all other post-emergence-plus-residual herbicides,” he says.
Scott Cully, Syngenta research and development scientist in Illinois, says compared to Halex GT, farmers in his area are seeing a 14% increase in residual control of Palmer amaranth between 42 and 56 days after treatment.
The longer residual gives farmers and retailers more flexibility on when they can apply the new premix.
“They don’t have to wait for weeds to emerge to make an application,” Cully says. “They can actually spray it earlier than they may have felt comfortable with (when using) previous products.”
The company recommends using Acuron GT, as part of a two-pass program, before weeds exceed 4″ to minimize potential yield losses.
“Based on the data, if we let the weeds get up to a 10″ height, we’ve lost approximately 15% yield of that corn,” Cully says, for example. “If you think about that in terms of a 200-bushel corn crop, that would become a 170-bushel crop.”
Company officials add that in 16 head-to-head replicated trials in glyphosate-tolerant corn, Acuron GT provided an average yield increase of up to 8 bu. per acre versus other post-emergence-plus-residual herbicides.
“That can be attributed to a combination of its safety and efficacy,” Cully says.
Matt Lehman, Syngenta formulation chemist, says Acuron GT has more than 20 different formulation components along with the latest in encapsulation technology, making it one of the most effective yet challenging herbicides the company has developed.
“It was difficult because it combines four active ingredients in different forms – a salt, two acids and an oil,” Lehman says. “Our team used various advanced formulation tactics to provide the stability and handling performance our customers require.”
Product formulations are important for growers to consider in the process of selecting herbicides, he says because they often differ between branded products and generics.
“A lot of what formulation chemists and engineers do is fight gravity by manipulating how solids and liquids interact,” he says.
While the product was available for application on a limited basis this season, company officials anticipate Acuron GT will be available for wide-scale use by farmers in 44 states for 2022.