Test For Herbicide Resistance

Fields with many weeds surviving herbicide application may suggest that the population is resistant. However, before rushing to this conclusion, one can do some diagnosis based on herbicide records, field patterns, and scouting observations.

Questions to ask:

- Which herbicide group and active ingredients were used?

- How were the conditions during spraying?

- Were there noticeable issues with the sprayer during herbicide spraying?

- Any field-scale patterns that indicate certain issues?

- When scouting, did you observe surviving weeds right beside dead weeds? (This is an indicator of potential herbicide resistance)

More information on field patterns and herbicide resistance: 

Pre-harvest weed scouting and herbicide resistance - Alberta Grains

Testing for Herbicide Resistance | Crop Production News 2024 - Issue #6 | Government of Saskatchewan

If herbicide resistance is suspected, collect weed seed samples and send to designated labs for herbicide resistance testing. Collect mature and healthy weed seeds from the suspected area. Dry them properly before shipping. Generally, a minimum of 2000 seeds per herbicide subgroup is required. Contact the testing labs for specific requirements.  

Labs accepting samples for herbicide resistance testing