This article was written collaboratively by Mark Rosenberg, former SDSU Extension Agronomy - Weeds Field Specialist, and Darrell Deneke, former SDSU Extension IPM Coordinator.
The following strategies should be effective in reducing problems with herbicide tolerant and resistant weed biotypes, but no strategy is likely to be totally effective alone.
- Scout fields regularly and identify weeds that escape herbicide treatment. Monitor changes in weed populations and restrict spread of potentially resistant weeds that match the field history and herbicide pattern.
- Rotate herbicides with different modes of action in consecutive years.
- Apply herbicides in tank-mix, prepackage or sequential mixtures that include multiple modes of action. Two or more herbicides in the tank-mix must have substantial activity against potentially resistant weeds. Most commercial premixes do not contain herbicides that target the same weed species.
- Rotate crops, particularly those with different life cycles, e.g., winter annual crops (winter wheat), perennial crops (alfalfa), summer annual (spring wheat, corn or beans). Do not use herbicides with the same mode of action in the different crops unless other effective control practices are also included.
Specific herbicide resistant weed management suggestions for South Dakota can be found in the SDSU Extension Pest Management Guides by checking out the resistant weed section. Guides are available by crop at the iGrow Store.
For a comprehensive list of resistant weeds in South Dakota, U.S., and world, visit the International Survey of Herbicide Resistant Weeds website.