The risk of herbicide resistance can be decreased by using:

• A. Crop rotations
• B. Herbicide rotations
• C. Mixtures of herbicides that have a different MOA
• D. All of the above

Answer: (D)

Using crop rotations, rotating herbicides with different modes of action, and mixing herbicides that have distinct modes of action all help reduce the chance that weeds survive and reproduce after exposure. Crop rotations change the weed community and cultural practices from season to season, which lowers the reliance on a single herbicide and the selective pressure that drives resistance. Rotating MOAs means not using the same herbicide mechanism repeatedly, so any resistant weeds are less likely to be favored across multiple seasons. Tank mixtures that pair herbicides with different modes of action kill through more than one mechanism at once, making it harder for weeds to possess resistance to all of them. When these strategies are combined, the overall pressure selecting for resistance is minimized, helping preserve herbicide effectiveness longer.