Scouting is all about early detection. And when it comes to weed detection, sooner is always better. The key to successful weed management is identifying resistance early, when the infestation can still be controlled.

Timing is everything. Timely scouting is key to making appropriate management decisions. Scout fields early and often to keep weeds under control. In-season scouting should begin shortly after planting to evaluate weed control efficacy and to determine if additional control is needed. Continue to monitor weed sizes and populations throughout the season. Failure to scout and apply POST herbicides in a well-timed manner could reduce the efficacy and increase the risk of herbicide resistance.

Scouting for Resistance

Know the signs. Herbicide resistance can’t be confirmed with a visual inspection, but the following signs could indicate its presence.

  • Failure to control a weed species normally controlled by the herbicide at the dose applied, especially if control is achieved on adjacent weeds.
  • A spreading patch of non-controlled plants of a particular weed species.
  • Surviving plants mixed with controlled individuals of the same species.

If herbicide resistance is suspected, samples should be collected for testing and escapees should be controlled before seed production.