National Glyphosate Sustainability Working Group, 2005.
Photo: Emma Leonard

Glyphosate Resistant Weeds in Australia
Glyphosate resistance was first documented for annual ryegrass (Lolium rigidum) in 1996 from a site in Victoria.  In 2007, glyphosate resistance occurred in populations of awnless barnyard grass (Echinochloa colona) in New South Wales.  In 2008, glyphosate resistance occurred in populations of liverseed grass (Urochloa panicoides) in New South Wales.  Currently, there are 98 documented glyphosate-resistant populations of annual ryegrass, 3 documented glyphosate-resistant populations of awnless barnyard grass and 2 documented glyphosate-resistant populations of liverseed grass.

Glyphosate resistant annual ryegrass has occurred in the following situations:

The glyphosate-resistant awnless barnyard grass and liverseed grass populations all occur in summer chemical fallow situations in NSW.

The increase in confirmed cases of glyphosate-resistant weeds between 1996 and 2008 is:

Glyphosate-resistant annual ryegrass populations by states:

All of the glyphosate resistant populations have occurred in situations where there has been intensive use of glyphosate, often over 15 years or more, few or no other effective herbicides used, and a few or no tillage operations.  This suggests the following are the main risk factors for the evolution of glyphosate resistance:

·         Intensive use of glyphosate – every year or multiple times a year for 15 years or more

·         Heavy reliance on glyphosate for weed control

·         No other weed controls

The full register of glyphosate resistant populations in Australia is available here.

Acknowledgements: 
 I would like to thank Dr. Rex Stanton and John Broster of Charles Sturt University, Prof Steve Powles of WAHRI, Dr. Peter Boutsalis of Plant Science Consulting and Dr. Abul Hashem of Department of Agriculture, Western Australia for sharing data from their testing.

How to cite this information: Preston, C. (2009) Australian Glyphosate Resistance Register. Australian Glyphosate Sustainability Working Group. Online. Available www.glyphosateresistance.org.au

For more information on the content of the Australian Glyphosate Resistance Register contact Dr. Chris Preston, phone: 08 8303 7237 email: christopher.preston@adelaide.edu.au

This register has been produced by the Australian Glyphosate Sustainability Working Group, a collaborative initiative aimed at promoting the sustainable use of glyphosate in Australian agriculture. CRC for Australian Weed Management, Monsanto, Syngenta, Nufarm, WA Herbicide Resistance Initiative (University of WA), University of Adelaide, Charles Sturt University, Queensland DPI&F (DEEDI), Department of Agriculture WA, Industry & Investment NSW, CRT/Town & Country, CRDC and the GRDC.

The AGSWG gratefully acknowledges the financial support of the GRDC.

Last updated: 07/10/2009