Weed Resistance Management

Know Your Herbicide Mode of Action

When herbicides that affect the same biological site of action are used repeatedly over several years to control the same weed species, naturally occurring resistant biotypes may survive, propagate and become dominant in your field. One important way to manage herbicide resistant weeds, is to use herbicides with different modes of action.


Linuron (Linex®4L, Lorox®DF) is a Group 7 herbicide, which acts at a different binding site from many other herbicides like atrazine and metribuzin (Group 5) and bromoxynil (Group 6). Linuron offers both  pre-emerge and postemergence burn down control of many broadleaf and grassy weeds and it can be tank mixed with paraquat or other burn down products where appropriate, to maximize postemergence weed control.

Also, linuron’s shorter plantback interval for some crops allows more flexibility versus other herbicides such as atrazine and diuron. Consult the LINEX or LOROX label for more information.

Use the NovaSource Herbicide Classification Guide to determine which modes of action you’ve been using.


Helpful Links & Info:

Herbicide Resistance Action Committee            

Weed Science Society Learning Modules

Herbicide Technical Information

Registry of Herbicide Resistant Weeds

Managing Herbicide Resistance-UC Davis

Managing Herbicide Resistance

Additional Tips for Preventing Herbicide Resistance:

  • Cultivate fields to eliminate weed escapes.
  • Plant clean, certified seeds.
  • Monitor fields for weed escapes.
  • Keep accurate records.
  • Prevent weeds from flowering and producing seed.
  • Rotate crops to decrease the likelihood of resistance developing.
  • Use herbicides that don’t last long in the soil profile.