Getting the best out of Group A grass herbicides

Best use of Group A grass herbicides may result in more than 3-5 years effective life.

Misuse may result in resistance in 3-5 years and the loss of Group A mode-of-action for grass weed management (as has happened in Thailand, Vietnam and California).

The Group A mode-of-action is known to be high risk for resistance management (CropLife Australia). 

Key messages:

  • BARNSTORM and AURA are high risk for development of resistance in grass weeds.
  • Integrated Weed Management (IWM) must be employed in all instances – use all other options first or together with Group A herbicides.
  • Think diversity. Use as many tactics to reduce weed numbers as possible and use Group A herbicides as the last option, NOT the only option as this will fail.
  • Weed seed production must be stopped every season. Survivors that set and shed seed will lead to more rapid onset of resistance.
  • Using all the techniques available, Group A grass herbicides may be effective into the next decade, which will allow most efficient production of high value rice in Australia.

Greg Wells, R&D Leader Southern Australia, Dow AgroSciences, Greg Sefton, Senior Agronomist, IK Caldwell Malcolm Taylor & Agropraisals Pty Ltd, Rice Pre-season 2014