Western Australia
April 3, 2014
Glyphosate resistant annual ryegrass in stubble
Wheatbelt farmers are being urged to take steps to lower glyphosate resistance in annual ryegrass after a survey showed over 40 per cent of samples displayed some form of resistance.
Department of Agriculture and Food senior research officer Sally Peltzer coordinated the survey, funded by the Grains Research and Development Corporation, prior to 2013 harvest to raise the awareness of glyphosate resistance and determine how widespread it was.
Dr Peltzer said the survey focused on weedy paddocks, proposed by growers, agronomists and growers groups, for seed collection.
“Forty two per cent of the seed samples tested to date have some glyphosate resistance, with 32 per cent weak (or developing) resistance, eight per cent intermediate resistance to the lower glyphosate testing rate and 10 per cent of the samples showing some resistance to the high rate of glyphosate,” Dr Peltzer said.
“The populations with weak resistance are very difficult to spot in the paddock and many of the growers were surprised by their results.
“It is likely glyphosate resistance is developing on many properties without the growers being aware. This could be due to low levels of herbicide resistance testing being conducted on farms in general.”
Dr Peltzer said now was the time for farmers to act on glyphosate resistance.
“The best practices to prolong the effectiveness of glyphosate include applying full herbicide rates under the best conditions possible, killing any survivors of the glyphosate application, by using double knock, rotating herbicide modes of action (including on fence lines) and using harvest weed seed management,” she said.
“The department is working with local agronomists on three regional best practice guides for preventing and managing glyphosate resistance which should be available later this year.
“Fence line trials aimed at preventing and managing glyphosate resistance will also be part of field days and field walks across the Wheatbelt this spring.
The glyphosate survey research was undertaken in collaboration with Australian Glyphosate Sustainability Working Group, Plant Science Consulting and Adelaide University.
Further information about glyphosate resistance can be found at http://www.weedsmart.org.au/ or http://glyphosateresistance.org.au/
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