Many of Western Australia’s 6000 graingrowers are now applying knockdown herbicides, signalling a key time to monitor for early signs of glyphosate resistance. Detection and quick treatment of resistant weeds is integral to controlling their populations.

Growers can arrange free glyphosate resistance tests of suspicious weeds by contacting the University of Western Australia-based Western Australia Herbicide Resistance Initiative (WAHRI).

The free testing, supported by the Grains Research and Development Corporation (GRDC), should help growers contain the spread of resistance genes, which can transfer to new plants through pollen, according to WAHRI researcher, Paul Neve.

"Early detection of resistant plants enables steps to be taken to prevent seed set and reduce the potential spread of resistance to neighbouring paddocks," he said.

Surveys have shown that a history of regular glyphosate use has led to a greater risk of glyphosate resistance developing on a large proportion of Western Australia paddocks.

Field experience and modelling suggests that if paddocks have received more than 12 glyphosate applications, growers should search for signs of resistance.

The benefit of early detection has been demonstrated in the northern agricultural region, where Western Australia’s first glyphosate resistant population was detected early and successfully placed under intense control to contain the resistant population.