Written collaboratively by Eric Jones, Philip Rozeboom, Jill Alms, and David Vos.
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.
A similar statement can be made with herbicides. If an herbicide is effective, chances are the herbicide will be applied more often. Overreliance on a single herbicide can result in selection for resistant weeds over time. Try to rotate the herbicide and apply mixtures to reduce the selection pressure.
Where were the weedy fields?
Fields that were infested with later emerging weeds or did not receive timely herbicide application(s) should be recorded as places where management intensity should likely increase. Other historically weedy field(s) should also be regularly scouted to ensure tactics are being conducted timely. These fields should be a focal point for weed management.
What weed species were present?
Since 2025 was a relatively wet season, more weeds that prefer wet conditions (i.e., barnyardgrass and smartweed) produced a lot of seeds and were present at the beginning of the 2026 season. The 2026 growing season was dry and may have more weeds that preferred dry conditions (i.e., kochia) producing seed to persist into 2027. Knowing what weed species were present in fields will help with purchasing the correct herbicide (pre- and postemergence). Again, weed management should be treated on a field-to-field basis as herbicides can be effective on some weed species and not others. Consult the most-recent South Dakota Pest Management Guides and specific herbicide labels for a comprehensive list of herbicides labeled and species controlled.
Can non-herbicide weed management easily be implemented?
While herbicides are the most efficient and effective weed management tools, implementing non-herbicide tactics can provide additional control under adverse conditions (Figure 2). Non-herbicide tactics also reduce the selection pressure for herbicide-resistant weeds. Easily implemented tactics include tillage (prescription tillage or adopting no-till), row spacing (i.e., drill-planted soybean or 20-inch row corn), fertilizer (make crops more vigorous and competitive with weeds), mowing ditches/fence lines, and hand weeding small, isolated patches. Some of these tactics will have the most utility to be utilized for site-specific management compared to implementing across the entire farm.
Should a different crop rotation be used in certain fields?
Crop rotation will allow for the use ofdifferent herbicides and tactics to manage various weeds and reduce reliance on a single tactic. Additionally, rotating crops with a different lifecycle (i.e., winter vs summer annual or perennial) can provide management by simply disrupting the lifecycle of weeds. Small grains are planted before many summer annual weeds germinate and can be a physical barrier to germinating weed seeds. Weed management can also be implemented after small grain harvest to reduce the amount of weed seeds produced. Fields that have serious weed infestations can be rotated to a perennial crop such as alfalfa that can be more competitive. Summer annual weeds cannot survive repeated cuttings and constant vegetation reduces the amount of seed germination.
While crop rotation can improve weed management in some instances, some crops should be avoided with specific weed problems are present. Conventional soybean should not be planted in fields with difficult to manage weeds (i.e., kochia or waterhemp) as there are limited herbicide options. Similar is true with other crops such as sunflower. This is not meant to discourage the planting of these crops but to be conscious of where some crops may not be feasible. These crops should be planted in fields where there are minimal weed issues and intensive management tactics can be used to keep yield potential high.
Did any herbicide control failures occur not attributable to adverse weather conditions or misapplications?
A control failure may not always mean herbicide-resistant weeds, but caution should be exercised where the failure occurred. Try to use a different herbicide from the previous year, use different herbicides in the pre- and postemergence applications and utilize approved herbicide tank mixtures. If control failures still occur, report the problem so appropriate measures can be taken to determine if the weed is resistant or not. South Dakota State University Extension is currently working on surveying the state to determine the distribution of herbicide-resistant weeds (Suspect Herbicide Resistance in Your Fields? SDSU Can Help!).
Prepare for the worst, hope for the best.
While there will never be a perfect weed management plan, utilizing many tactics will aid in increasing effectiveness under all conditions. While the conditions for the 2027 growing season are still largely unknown, prepare for adverse conditions so weed management can be a relatively simple task.
The use of trade names is for clarity to readers and does not imply endorsement of a particular product, nor does exclusion imply non-approval.
