Is Herbicide Resistance to Blame?

Most weed control failures are not due to resistance. Before assuming weeds surviving an herbicide application are resistant, eliminate other possible causes of poor control:

    1. Herbicide application
      1. Inadequate rate
      2. Poor spray coverage and/or incorporation
      3. Improper timing of application of postemergence herbicides (after weeds are too large to control)
      4. Failure to use an adjuvant (if needed)
      5. Excessive dust with post-emergence applications
      6. Spray intercepted at application by wheel traffic
      7. Antagonism between two or more herbicides
    2. weeds in dry soilSoil and/or climatic conditions
      1. Excessively wet or dry soil
      2. Seedbed condition (clods, etc.)
      3. Herbicide adsorption to soil particles or organic matter
      4. Stress conditions, such as hot and dry
      5. Lack of timely rainfall for activation
      6. Wash-off of post-emergence herbicides

Additional Resources

Compiled by Dr. Wayne Buhler, PhD.

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