Written collaboratively by Eric Jones, Philip Rozeboom, Jill Alms, and David Vos.
As the 2025 harvest season comes to an end, now is the time to start preparing 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 so well? Consider factors that influenced weed management such as herbicide selection/rate, weed species, crop rotation and soil type. While weather likely played a role in weed management, controlling the weather is out of our hands. Considering these factors can help shape our weed management plans for 2026. Even if weed management was successful, continuously changing tactics can reduce weed adaptation to those tactics. Another consideration for weed management is to create plans for individual fields. Each field likely has unique soil types, landscape features, and weed species; tailoring your management plan to the unique characteristics of the field will likely be more effective in both management and costs. 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?
Where were the weedy fields?
There were many fields in 2025 that were drowned out due to rain. These areas are usually inhabited by weeds and therefore should be a focus for management in 2026. Fields that were infested with later emerging weeds or did not receive timely herbicide application(s) should be recorded as places were management intensity should likely increase. Other historically weedy field(s) should also be regularly scouted to ensure tactics are being conducted timely.
What weed species were present?
Since 2025 was a 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 2025 season. The growing season was also wet and may have more weeds that preferred wet conditions producing seed to persist into 2026. 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 for a comprehensive list of herbicides labeled and species controlled.
Can non-herbicide weed management easily be implemented?
While herbicides are the most effective weed management tools, implementing non-herbicide weed control tactics can provide additional control and 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), mowing ditches/fence lines, and hand weeding small, isolated patches. Some of these tactics will have the most utility for site-specific management compared to implementing across the entire farm. Utilizing various nonchemical, diverse tactics will also increase weed management during adverse weather conditions when herbicides are not as effective.
Should a different crop rotation be implemented in certain fields?
Crop rotation will allow for the use of different herbicides to control various weeds and reduce reliance on a single herbicide. Additionally, rotating to crops with a different lifecycle (i.e., winter vs summer annual or perennial) can provide control by simply disrupting the lifecycle of weeds. Wheat and 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 wheat/small grain harvest to control weeds that are present, so seeds are not 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 implement intensive management tactics to keep yield potential high.
Did any herbicide control failures occur that were 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 a different herbicide 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. SDSU 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 diverse tactics will aid in increasing effectiveness under all conditions. While the conditions for the 2026 growing season are still largely unknown, prepare for adverse conditions so weed management can be a relatively simple task.
