Globally, herbicide resistance to Group A herbicides has been confirmed and documented in more than 40 grass weed species across more than 40 countries. Group A resistance is extensive and prolific with tens of millions of hectares affected, in fact it is the second most likely herbicide mode of action to develop resistance with only the Group B mode of action more likely.
Group A resistance commonly exists across wide areas of Australia in the grass weed species including more than 20,000 populations of annual ryegrass, annual veld grass, more than 5,000 populations of wild oats, phalaris, more than 200 populations of brome grass, crabgrass, crowsfoot grass and more than 200 populations of 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.
The above recommendations should be incorporated into an Integrated Weed Management (IWM) program. In all cases try to endure surviving weeds from any treatment do not set and shed viable seed. Keep to integrated strategies mentioned in this brochure including cultural weed control techniques to reduce the weed seedbank. Make sure you mix and rotate herbicides from different mode of action groups. Always consult the product label prior to use.
|GROUP A||Inhibitors of acetyl co-enzyme A carboxylase (Inhibitors of fat synthesis/ACC’ase inhibitors)|
|Aryloxyphenoxypropionates (Fops):||clodinafop (Topik®), cyhalofop (Agixa®*, Barnstorm®), diclofop (Cheetah® Gold* Decision®*, Hoegrass®), fenoxaprop (Cheetah®, Gold*, Wildcat®), fluazifop (Fusilade®), haloxyfop (Verdict®), propaquizafop (Shogun®), quizalofop (Targa®)|
|Cyclohexanediones (Dims):||butroxydim (Factor®*), clethodim (Select®), profoxydim (Aura®), sethoxydim (Cheetah® Gold*, Decision®*), tralkoxydim (Achieve®)|
|Phenylpyrazoles (Dens):||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.
Content last updated: June 10, 2020