Specific guidelines for Group 03 herbicides

Moderate resistance risk

Globally herbicide resistance to the Group 3 herbicide mode of action has been confirmed and documented in more than 10 grass and broadleaf weed species across more than 8 countries.

Group 3 resistance exists in Australia in 3 weed species including 5,000 populations of annual ryegrass and dense flowered fumitory. Resistance has generally occurred after 10 -15 years of use of Group 3 herbicides.

Where possible, avoid the use of Group 3 herbicides on dense ryegrass populations. Consider using alternative methods of weed control to reduce weed numbers before applying herbicides.

To assist in delaying the onset of Group 3 resistance, rotate and/or tank mix with herbicides from other modes of action.

Use Group 3 herbicides at robust rates e.g. the maximum label rates to ensure high levels of weed control particularly when targeting annual ryegrass.

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 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.

Chemical family Active constituent (first registered trade name)

Inhibition of microtubule assembly

Benzamides propyzamide (Effigy*®, Kerb®)
Benzoic acids chlorthal (Dacthal®, Prothal®*)
Dinitroanilines: (DNAs) oryzalin (Rout®*, Surflan®), pendimethalin (Freehand*®, OH2 Ornamental Herbicide®, Stomp®), prodiamine (Barricade®), trifluralin (Bolta Duo*, Jetti Duo®*, Treflan®)
Pyridines dithiopyr (Dimension®)

* This product contains more than one active constituent


  1. 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 (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-3-herbicides/
Content last updated: June 26, 2024

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 26 June 2024. All previous versions of this strategy are now invalid.