Herbicide future under threat

HERBICIDES are one of the most important tools in a no-till farmer's arsenal, but increased - and sometimes incorrect - use has the potential to render these vital chemicals ineffective.

Speaking at a recent herbicide resistance forum at Karoonda, organised by the Mallee and Coorong NRM group and the Karoonda Ag Bureau, the Australian Herbicide Resistance Initiative's Peter Newman, Geraldton, WA, said resistance was a growing problem.

"Herbicide resistance is a big issue worldwide, and in Australia WA and parts of SA have been the leaders," Mr Newman said.

While herbicide resistance in the SA Mallee is not as great as other parts of the country, issues are starting to crop up.

"Our big concern for this part of the world is that brome grass will very quickly evolve resistance to Imi (imidazolinone) herbicides and once they fall over these growers are going to have a lot of trouble on their hands, so we're trying to intervene before that happens and make those herbicides last a lot longer.

"The reason more farmers don't have Imi resistance is because they haven't used enough of it, but it will happen - it's not one of those low-risk groups," he said.

"If you're just in the stage of getting a few resistant populations, that's the warning sign that it's going to happen."

He said herbicides were not the answer to herbicide resistance.

"Herbicides are fantastic - but has anyone actually completely eradicated ryegrass on their property? We've had 30 to 40 years of new ryegrass herbicides coming out, and we've still got ryegrass. Herbicides are brilliant, but they're not the complete answer," he said.

"With a lot of farmers, when herbicide resistance bites, they just start rotating herbicides. They're still living year-to-year, just focusing on killing this year's weeds, then it's all the same the next year. As soon as farmers make it about the seed bank, they start to have wins.

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Herbicide future under threat