Specific guidelines for Group Z herbicides

Moderate resistance risk

Globally, herbicide resistance to the Group Z herbicide mode of action has been confirmed and documented in 5 weed species across 4 countries.

Group Z resistance exists in Australia in more than 200 populations of wild oats resistant to flamprop. Many of these flamprop resistant wild oats also show cross resistance to Group A herbicides. There is also endothal resistance confirmed in annual poa (winter grass).

To assist in delaying the onset of resistance, rotate with herbicides from other modes of action.

Consider using alternative methods of weed control to reduce weed numbers before applying herbicides. These may include summer crop rotations, delayed sowing to control wild oats with a knockdown herbicide, higher seeding rates, brown manuring to stop seed set, etc.

The above recommendations should be incorporated into an Integrated Weed Management (IWM) program. In all cases try to ensure surviving weeds from any treatment do no 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 Z Herbicides with unknown and probably diverse sites of action
Arylaminopropionic acids: flamprop (Mataven L®)
Dicarboxylic acids: endothal (Endothal®)
Organoarsenicals: DSMA (disodium methylarsonate) (Methar®, Trinoc®*), MSMA (monosodium methylarsonate) (Daconate®)
Fatty acids: Pelargonic acid (Nonanoic acid)

* 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. 

URL: https://croplife.org.au/resources/programs/resistance-management/specific-guidelines-for-group-z-herbicides-draft/
Content last updated: June 10, 2020

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

The information given in this strategy is provided in good faith and without any liability for loss or damage suffered as a result of its application and use. Advice given in this strategy is valid as at 10 June 2020. All previous versions of this strategy are now invalid.