Australian Herbicide Resistance Initiative (AHRI) insight #105 - Alphabet cross-resistance in South Australia
Australia
August 30, 2018
Do you want the bad news, the really bad news, or the really really bad news?
I’ll ease you into it.
The bad news: A population of ryegrass from the Eyre Peninsula, South Australia has been confirmed resistant to all of the pre-emergent herbicides – Avadex, Arcade, Trifluralin, Propyzamide and Sakura, as well as two lesser-known herbicides EPTC and Thiobencarb.
“Crikey, this is the bad news! Surely it can’t get any worse”
The really bad news: It was sampled in 2014 just two years after the release of Sakura in Australia. You guessed it, metabolic cross-resistance is at play.
“Okay, give it to me, nothing will surprise me now!”
The really really bad news: A random survey in the South East of South Australia found many more populations of ryegrass with multiple cross-resistance to a range of pre-emergent herbicides, and the perplexing thing is that there is no predictable cross-resistance pattern.
“I’m going to have a cup of tea, a Bex, and a good lie down!”
This is the research by the team of Chris Preston, Peter Boutsalis, David Brunton and Gurgeet Gill from the University of Adelaide with GRDC investment.
Peter Newmans says this is the worst herbicide resistance news he's ever seen in his 25-year long career, simply due to the fact that so many herbicides are failing simultaneously.
But all is not lost, and we need to be on the front foot to give ourselves the best chance of success. If you suspect that you have had a pre-emergent herbicide failure this year due to resistance a first steps action plan could be:
Stop seed set if you can;
And adopt harvest weed seed control now;
And test;
And use the testing results to develop a mix and rotate strategy; and
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