The extent of herbicide resistance in rice crops of southern New South Wales

John Broster and Allison Chambers

Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia. Email:


Herbicide resistant weeds are a major problem in the cropping regions of Australia.  The rice industry is no exception since weed control in the rice industry has been dependent on only a few herbicides.A random survey in 1999 reported significant levels of resistance to one of the major herbicides (bensulfuron or Londax®) across the rice growing regions of southern New South Wales. The survey was repeated in both 2016 and 2017 to assess current herbicide resistance levels.  Resistance was confined to bensulfuron.  Since the previous survey in 1999, bensulfuron resistance had increased from 46% of dirty dora populations to 70% in 2017 and for arrowhead from 38% to 61%.  The extent of resistance in starfruit at 50% was similar to that reported for the 1999 survey.  While there was no resistance confirmed to other herbicides or species, three accessions (two with dirty dora and benzofenap; one with barnyard grass and propanil) had survival levels above the resistance thresholds used, these populations require further testing to confirm resistance status.


The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography Graham Centre for Agricultural Innovation, Charles Sturt University

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