Ultimate Weed Management Checklist

Herbicide resistance is a growing issue in the Pacific Northwest and around the country and globe. In the past couple of years alone, we have identified numerous populations of downy brome that are resistant to the ALS-inhibiting herbicides such as Outrider, Olympus, PowerFlex, and Beyond, as well as Russian-thistle biotypes resistant to glyphosate and kochia biotypes resistant to dicamba. Dr. Burke, WSU Weed Scientist, recently confirmed a jointed goatgrass biotype resistant to Beyond herbicide and he currently has a downy brome population that he strongly suspects is resistant to glyphosate. Clearly, the weeds seem to be winning the battle with herbicides.

The Weed Science Society of America has developed several resources to help growers manage the problem of herbicide resistance.

One such resource is the Ultimate Weed Management Checklist:

  1. Make a plan – Think long-term. Strategize to delay the evolution of herbicide resistance and reduce weed seeds
  2. Go full-rate – Apply full rates of effective pre- and postemergent herbicides with multiple modes of action (MOAs). Dead plants can’t produce resistant progeny
  3. Get ‘em when they’re little – Spray weeds when they’re shorter than 4 inches. Don’t wait
  4. Spice things up – Don’t stick with the same old single MOA. Use multiple, effective MOAs everywhere, every time
  5. Scout it out – Correctly ID weeds by species. Kill weeds that escape an herbicide application
  6. Zero tolerance policy – Destroy uncontrolled weeds, which might mean you have to pull them by hand. Seed from escaped weeds will contribute to the weed seedbank
  7. Don’t ditch your ditches – Weeds aren’t limited to your fields. Don’t let them thrive in forgotten field edges, fence lines, and waterways
  8. Keep it clean – Don’t let weed seeds hitch a ride. Clean tillage and harvest equipment
  9. Do more than spray – Consider using mechanical and/or cultural control practices, like tillage or cover crops
  10. Re-evaluate and repeat – Review your weed-management results at the end of each season and revise to improve next year
Wheat growers can find other useful resources for managing weed resistance on the Weed Resources pages of the Wheat and Small Grains website. These resources include:

Anytime is a good time to review your weed management strategies, especially in light of the increasing incidence of herbicide-resistant weeds throughout the Pacific Northwest.

For questions or comments, contact Drew Lyon by email at drew.lyon@wsu.edu or by phone at 509-335-2961.
Washington State University