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12 February 2009
Challenge issued on IWM
Glyphosate-resistant crops will provide benefits and opportunities only if they are used as part of an IWM package, according to Deirdre Lemerle, Director of the EH Graham Centre for Agricultural Innovation
Professor Lemerle challenged advisers at the GRDC Adviser Update at Wagga Wagga on February 10 and 11 to develop and present a 'clear, concise and consistent' message on integrated weed management (IWM) or risk losing glyphosate, one of Australian farmers' most useful weed control tools.
'With the arrival of GM herbicide-tolerant canola the ball is in our court and we have the responsibility to help growers understand how and why resistance develops and the economic importance of IWM to stop resistance spreading."
She has no doubt that glyphosate-resistant canola can increase weed control options, enhance adoption of no-till methods and stubble retention and increase grower returns but says the technology will 'inevitably fail' if used in isolation instead of as part of an IWM package.
Australia needs to learn from the Canadian experience with glyphosate-resistant canola in farming systems, Professor Lemerle says.
"The positive Canadian experience with herbicide-resistant crops, compared to the problems being encountered in the US, shows it is essential our producers adhere to stewardship guidelines for glyphosate-resistant canola."
However, research indicates many producers are confused about how herbicide resistance develops and the benefits of IWM.
A 2007 survey of advisers in southern NSW indicated growers are aware of herbicide resistance but have only poor understanding of how and why weed populations develop resistance to herbicides and many are not using effective IWM strategies.
This is despite repeated reiteration of the message that resistance is a numbers game - reduce seedbanks and herbicide hits to reduce the risk of resistance.
The IWM message needs revitalising, she says, and suggests a focus on the financial benefits of IWM may be the missing link.
"We need clear and consistent messages and demonstration of the economic, agronomic and environmental benefits of IWM.
"A long-term approach to weed management takes skill and time but the economic benefits are large. A reduction in weed numbers in any period will result in future economic benefits and conversely any increase will lead to future economic costs.
"The IWM message is 20 years old and must be updated to include current local agronomic and economic data supported by local case studies and promoted by producer champions."
New weed control options including mulch/cover crops, innovative herbicide options, allelo-chemicals, and glyphosate-resistant canola will all be part of the future IWM tool box, she predicts.
Contact: Deirdre Lemerle, dlemerle@csu.edu.au, tel (02) 6938 1667.