Palmer amaranth remains one of the most difficult weeds to manage, and when pigweed escapes preemergence control, postemergence decisions can quickly turn into a kitchen sink approach where multiple products are added to the tank. Because postemergence options depend on the crop system and trait technology, we evaluated a wide range of postemergence programs in 2025 to better understand overall control trends.
Location Still Matters: Postemergence pigweed control varied by location and population. At some locations, control at 14 days after application was consistently high across programs, while at others, clear differences among programs were observed (Figure 1). This reinforces that pigweed populations and field conditions strongly influence postemergence performance.
Atrazine Is Still Working Across the programs evaluated, atrazine continued to provide strong postemergence pigweed control (Figure 2). This is encouraging for corn growers, as atrazine-containing programs frequently ranked among the higher-performing treatments and remain an important management tool.
Tank Mixes Improve Control In addition to atrazine, tank mix programs generally provided better postemergence pigweed control than single product applications. Combining effective herbicide modes of action often improved consistency, particularly at more challenging locations. However, adding more products did not always result in better control, reinforcing that program design matters more than product count.
Take Home Message
There is no single postemergence solution for Palmer amaranth. Results from this kitchen sink evaluation reinforce that atrazine is still working, tank mix programs tend to improve control, and pigweed response can vary widely by population. Looking ahead, these results are meant to provide food for thought before we get into the weeds of postemergence management decisions. While postemergence herbicide choices will always depend on the crop system and available products, these data highlight general trends in how different programs have performed when pigweed escapes occur, because they will.
