Moderate resistance risk

Resistance to Group I herbicides is known for a number of populations of capeweed, common sow thistle, wild radish and Indian hedge mustard. Resistance has occurred after a long history of use of Group I herbicides. The number of populations with Group I resistance is increasing.

Of particular concern is that apart from the resistance being in wild radish which is the most important broadleaf weed in broadacre agriculture, some populations may also have resistance to other modes of action eg. Group F herbicides which can be important for control of wild radish in lupins where other selective non Group I options are limited. Because of the long soil life of wild radish seed, measures to reduce seed return to the soil would be useful for this weed. Wild radish seed that is confined to the top 5 cm soil has a shorter life than seed buried deeper.

As a general rule in high resistance risk situations

1. Avoid applying 2 applications of Group I herbicides alone onto the same population of weeds in the same season. To assist in delaying the onset of Group I resistance, rotate and/or tank mix with herbicides from other modes of action

2. Where possible combine more than one mode of action in a single application. Each product should be applied at rates sufficient for control of the target weed alone to reduce the likelihood of weeds resistant to the Group I herbicide surviving.

All the above recommendations should be read in conjunction with the Integrated Weed Management (IWM) strategies

GROUP I Disruptors of plant cell growth (Synthetic Auxins)
Arylpicolinate: halauxifen (ForageMax®*,Paradigm®*)
Benzoic acids: dicamba  (Banvel®, Banvel M®*, Barrel®*, Casper®*, Mecoban® , Methar Tri-Kombi®*)
Phenoxycarboxylic acids:(Phenoxys): 2,4-D (Actril DS®*, Amicide®, Fallow Boss Tordon®*, Methar Tri-Kombi®*, Pyresta®*), 2,4-DB (Trifolamine®), dichlorprop (Lantana 600®), MCPA (Agtryne® MA*, Banvel M®*, Barrel®*, Basagran® M60*, Buctril® MA*, Chipco Spearhead®*, Conclude®*, Flight®*, MCPA, Midas®*, Multiweed®*, Paragon®*, Precept®*, Tigrex®*, Tordon 242®*, Triathlon®*), MCPB (Legumine®), mecoprop (Mecoban®, Mecopropamine®, Methar TriKombi®*, Multiweed®*)
Pyridine carboxylic acids:(Pyridines): aminopyralid (Fallow Boss Tordon®*, ForageMax®*, Grazon Extra®*, Hotshot®*, Stinger®*, Vigilant II®*),  clopyralid (Chipco Spearhead®*, Lontrel®, Torpedo®*), fluroxypyr (Hotshot®*, Starane®), picloram (Fallow Boss Tordon®*, Grazon Extra®*, Tordon®, Tordon 242®*, Tordon Regrowth Master®*, Trinoc®*, Vigilant II®*), triclopyr (Garlon®, Grazon Extra®*, Tordon Regrowth Master®*, Tough Roundup® Weedkiller*, Ultimate Brushweed®* Herbicide)
Quinoline carboxylic acids: quinclorac (Drive®)

* 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