Diflufenacin--A New Site-of-Action Herbicide for the US

All parties involved in production agriculture–e.g. scientists, extension specialists, producers, consultants, retailers–are aware that arguably the most egregious problem facing row crop producers in the midsouthern US is the resistance of Palmer amaranth (pigweed) to multiple herbicide sites of action. This problem weed must be controlled from burndown to “layby” and possibly beyond to ensure that it is eradicated so there is no seed production to replenish the soil weed seedbank.

Thus, the news release from Bayer titled “Bayer further commits to crop protection innovation with planned introduction of Diflufenican” is important since it announces that company’s introduction of a herbicide–diflufenican, Group 12–with a site of action new to US corn and soybean producers. The plan is for this new herbicide to be available as early as 2023 (pending EPA approval). It will be marketed with the brand name Convintro, and will target Palmer amaranth in burndown and preemergence applications. The company plans to package this new herbicide with metribuzin (Group 5) and flufenacet (Group 15) herbicides for use on soybeans.

This newly-available technology is important for three reasons. 1) It targets a new site of action in pigweed that has not been attacked by herbicides currently being used by US producers. 2) It will be available in a premix that contains herbicides that target multiple sites of action, thus lessening the potential for Palmer amaranth to develop resistance to it. This approach is a cornerstone of current best weed management strategies for US crop producers. 3) This herbicide product will be applied at the best time to control this problematic weed–i.e. before the crop is planted.

For additional information about controlling Palmer amaranth in soybeans, click Managing Herbicide-Resistant Palmer Amaranth on this website. Links in this article will access the most up-to-date strategies for controlling this problematic weed.

Composed by Larry G. Heatherly, June 2021, larryh91746@gmail.com