No-till farming at risk if glyphosate is lost says weed expert

Knockout blow: Our soils will suffer if we lose glyphosate says weed expert

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DIVERSITY CHAMPION: Professor Stephen Powles from the University of Western Australia says farmers need to to rotate herbicides more if they want to keep glyphosate in their weed arsenal.

DIVERSITY CHAMPION: Professor Stephen Powles from the University of Western Australia says farmers need to to rotate herbicides more if they want to keep glyphosate in their weed arsenal.

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One of Australia's foremost weed experts says agriculture must retain the herbicide glyphosate for as long as possible.

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Conservation farming in Australia will not survive without the knockdown herbicide glyphosate, according to one of Australia's leading weed experts.

Professor Stephen Powles from the University of Western Australia's School of Agriculture and Environment, says the widespread adoption of no-till cropping (conservation farming) had been built around glyphosate.

He said glyphosate had been a one-in-100-year technology that had paved the way for a cropping system which was protecting Australia's fragile soils while allowing broadacre farmers to maintain production during the past two decades of generally tough seasons.

Glyphosate was a "rare and precious discovery" and had allowed farmers to dump the "destructive" plough, he said.

However Dr Powles said glyphosate's future was being threatened by both increasing weed resistance and regulatory challenges with lawsuits over the herbicide's alleged impact on human health and the environment.

He said one million tonnes of glyphosate was now used around the world each year which meant residues of the chemical were going to show up in many places.

"Traces are going to be measurable in many places. No matter how benign and safe, there will be residues, often at low levels, but sophisticated analysis will find them," he told an Australian Farm Institute Conservation Agriculture in 2030 webinar.

"And this is one of the reasons why there are individuals and organisations who are opposed to glyphosate."

He said glyphosate was a victim of its own success and farmers were over-using it which was hastening weed resistance.

Glyphosate resistance had trebled weed control costs in the US and the problem was increasing in Australia.

Dr Powles said farmers had to adopt an attitude towards glyphosate of "when you are on a good thing, don't stick to it".

Farmers needed to minimise its use by diversifying chemicals and using new technologies such as precision spot weed spraying.

A survey had shown farmers were optimistic that a replacement for glyphosate would be available in the next 10 years but Dr Powles said producers should not bet on that happening.

"Fabulous" resources like glyphosate came along very infrequently, he said.

As for any human health and environmental risks posed by glyphosate, Dr Powles said the herbicide was registered and supported by major regulatory agencies around the world "and I trust and follow their recommendations".

He said the overwhelming consensus from studies showed glyphosate had no impact on soil biology.

Richard Dickmann, head of public and government affairs at Bayer Australia, told the webinar that glyphosate's great success had partly impacted on the development of new herbicides along with rising costs and regulatory requirements.

"Chemophobia" had been on the rise but there was no inherent difference between natural and man-made chemicals, he said.

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