High resistance risk Group A resistance exists in Australia in the grass weeds including annual ryegrass, annual veld grass, wild oats, phalaris, brome grass, crabgrass, crowsfoot grass and barley grass. Resistance has developed in broadacre and vegetable situations. Research has shown that as few as 6 applications to the same population of annual ryegrass can result in the selection of resistant individuals. A population can go from a small area of resistant individuals to a whole paddock failure in one season.
  1. Fops, dims and dens are Group A herbicides and carry the same high resistance risk.
  2. Where a Group A herbicide has been used on a particular paddock for control of any grass weed, avoid using a Group A herbicide to control the same grass weed in the following season, irrespective of the performance it gave.
  3. Frequent application of Group A herbicides to dense weed populations is the worst case scenario for rapidly selecting for resistance.
  4. Where resistance to a member of Group A is suspected or known to exist, there is a strong possibility of cross resistance to other Group A herbicides. Therefore use other control methods and herbicides of other mode of action groups in a future integrated approach.
All the above recommendations should be read in conjunction with the Integrated Weed Management (IWM) strategies
GROUP A Inhibitors of acetyl co-enzyme A carboxylase (Inhibitors of fat synthesis/ACC’ase inhibitors)

clodinafop (Topik®), cyhalofop (Barnstorm®), diclofop (Cheetah® Gold*, Decision®*, Hoegrass®), fenoxaprop (Cheetah® Gold* , Wildcat®), fluazifop (Fusilade®, Fusion®*), haloxyfop (Verdict®), propaquizafop (Shogun®), quizalofop (Targa®)

butroxydim (Falcon®, Fusion®*), clethodim (Select®), profoxydim (Aura®), sethoxydim (Cheetah® Gold*, Decision®*), tralkoxydim (Achieve®)

pinoxaden (Axial®)

* This product contains more than one active constituent

List of chemical families, approved active constituents and, in parenthesis, the trade name of the first registered product or successor.  Refer to the APVMA website (www.apvma.gov.au) to obtain a complete list of registered products from the PUBCRIS database. 

CropLife Australia’s Resistance Management Strategies provide a guide for crop protection product rotation through product groups.  The strategies are a useful tool that supports farmers’ adoption of resistance management.

All crop protection products must be handled and applied strictly as specified on the product label or APVMA permits.  These Resistance Management Strategies do not replace product labels.  They are a guide only and do not endorse particular products, groups of products or cultural methods in terms of their performance.  It is important to check with the Australian regulator’s (APVMA) product database for contemporary information on products and active constituents.  The database can be sourced through www.apvma.gov.au