By Eric Jones and Philip Rozeboom et.al
As the 2026 harvest season comes to an end, now is the time to start planning your weed management plan for next year. While purchasing herbicides, crop seed, and other inputs take priority after harvest, consider asking yourself the following questions to better prepare for managing weeds next season.
Questions to Consider
How was my weed management plan this year?
Reflect on how weed management was across the farm during 2026. What worked well? What did not work well? Dry conditions were realized across most of South Dakota at the beginning of the season, which may have caused preemergence herbicides to not activate. As the price of herbicides and other inputs continue to increase or remain high, the thought of removing preemergence herbicides from a management program may have crossed some minds. While the weather is out of our control, no preemergence herbicide will ever be activated if the herbicide is not applied. While three or more different herbicide groups are often recommended for a preemergence application (Figure 1), could two herbicide groups be selected based on the weed species present in each field? Utilizing at least two unique herbicides will result in improved effectiveness, management of more weed species and reduce selection pressure for resistance development.
Postemergence herbicide activity may have been decreased under the dry conditions as well. While mixtures of herbicides from different groups usually increase effectiveness, adding an herbicide with soil residual activity may help manage later flushes of weeds. Again, soil residual herbicides do require activating precipitation, but no herbicide can be activated if not applied. Also, consider including a postemergence residual herbicide in the fields that have been historically weedy. If a soil residual herbicide is added to the postemergence application, try to select a product that is different from what may have been applied preemergence.
Other factors that influenced weed management with herbicides could include product selection, rate, weed species, crop rotation and soil type. How can these factors be addressed now to improve weed management in 2027? Each field likely has unique soil types, landscape features, and weed species; tailoring your management plan to the unique characteristics of each field will likely be more effective. One crop variety is rarely planted across the entire farm, but specific varieties are planted to the characteristics of the field; why should weed management be any different?
Even if weed management was successful, continuously changing tactics can reduce weed adaptation. For example, tillage can be an effective tactic to manage weeds. However, under continuous tillage, more large-seeded weeds (cocklebur, sunflower, and velvetleaf) may be more abundant than small-seeded or perennial weeds. Whereas under continuous no-till, more winter annual and early germinating weeds (such as kochia) may be present since seeds are not being buried.
Source : sdstate.edu