Specific guidelines for Group K herbicides

Moderate resistance risk

Globally herbicide resistance to the Group K herbicide mode of action has been confirmed and documented in 5 weed species across 7 countries.

Resistance to Group K herbicides in Australia has developed in more than 20 populations of annual ryegrass. Further development of resistance in the near future is likely given the reliance on Group K herbicide chemistry for weed control across large areas of Australia.

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

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

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

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. 

GROUP K Inhibitors of cell division / Inhibitors of very long chain fatty acids (VLCFA inhibitors)
Acetamides: napropamide (Altiplano®*, Devrinol®)
Chloroacetamides: dimethenamid (Freehand*, Frontier®-P, Outlook ®), metazachlor (Butisan®), metolachlor (Boxer® Gold*, Dual® Gold, Primextra® Gold*), propachlor (Prothal®*, Ramrod®)
Isoxazoline: pyroxasulfone (Sakura®)

* 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-k-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.