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Australian Herbicide Resistance Initiative (AHRI)

Keep mixing herbicides

Tag Archives | mechanisms

Australian Herbicide Resistance Initiative (AHRI)

Keep mixing herbicides

Roberto recently completed a project with GRDC investment where he sampled ryegrass from 17 paddocks across eight farms in Western Australia to see if there are benefits of proactively testing for herbicide resistance.  Across these tests, he found ryegrass that was resistant to Clethodim (Select) or Butroxydim (Factor) but no ryegrass that was resistant to the mix of the two. The same went for the pre-emergent herbicides as well, no resistance to mixes.

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Australian Herbicide Resistance Initiative (AHRI)

Trifluralin resistance is different – recessive inheritance

We once thought that the genetics of eye colour was simple. Both parents have blue eyes, therefore, all of their children will have blue eyes. Easy peasy! Then science progressed and we realised that it isn’t actually that simple because several genes are involved. The genetics of herbicide resistance was simple. One parent is resistant to a herbicide, therefore, all of the offspring will be resistant because the gene is dominant or semi-dominant. This is true for almost all cases of herbicide resistance and was easy to understand. Until now. Click to read more about PhD student Jinyi Chen’s research.

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Australian Herbicide Resistance Initiative (AHRI)

2,4-D resistance in radish is not metabolic resistance

If I took a footballer, say Dustin Martin, and cut off one of his arms, chances are he wouldn’t function too well as a footballer anymore (although knowing Dusty he would probably work out a way around it!)If I then sewed his arm back on so it worked perfectly, he would be back to his Brownlow medal winning best.This is sort of what happens with 2,4-D in wild radish and explains why metabolic resistance is not the mechanism of wild radish resistance to 2,4-D.  We now know this thanks to some painstaking research by AHRI researcher, Danica Goggin with funding…

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Australian Herbicide Resistance Initiative (AHRI)

Wild radish resistant to Atrazine, super-sensitive to Bromoxynil

By Peter Newman Alexander Graham Bell famously said, “When one door closes another door opens, but we so often look so long and so regretfully upon the closed door, that we do not see the ones which open for us.” Atrazine resistant wild radish looks a lot like a door closing, but in many cases, it’s also a door opening for Bromoxynil. Some new research by AHRI PhD student, Huan Lu, has shed some light on Atrazine resistant wild radish and the results have some very practical applications for growers and agronomists. The most common target site mutation that causes…

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Australian Herbicide Resistance Initiative (AHRI)

Rare but predictable – A new target-site mutation for glyphosate resistance discovered

AHRI’s principal research fellow, Dr Qin Yu, in collaboration with other international researchers, has demonstrated that in Tridax daisy, glyphosate resistance is associated with the Thr-102 site mutation alone. In contrast to earlier investigations with goosegrass, where both the Pro-106 and Thr-102 sites (TIPS) mutation endowed glyphosate resistance, this study has demonstrated that selection for a mutation at Thr-102 alone can lead to moderate level glyphosate resistance in the field.

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Australian Herbicide Resistance Initiative (AHRI)

Metabolic trifluralin resistance

Just when we thought we understood the mechanism of trifluralin resistance we blink and find another. Earlier in the year, we reported on research by AHRI PhD student Jinyi Chen confirming that a target site mutation that infers resistance to trifluralin. Earlier in the year, we reported on research by AHRI PhD student Jinyi Chen confirming that a target site mutation that infers resistance to trifluralin. Now Jinyi has confirmed that metabolic resistance to trifluralin is also possible.

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Australian Herbicide Resistance Initiative (AHRI)

‘Clear and present danger’ – glyphosate resistance in the North

Researchers and growers have long been anticipating glyphosate resistance in the Northern cropping region and now the preliminary results from the first herbicide resistance survey in the region are confirming the ‘clear and present danger’ facing the grains industry. While growers have previously enjoyed the ‘freedom’ to use this herbicide as their go-to, highly effective tool for weed control, there’s now strong evidence that they should look for ways to protect this mode of action and implement a variety of tools such as the double knock, rotating herbicides and seed bank management as a matter of urgency.   

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Australian Herbicide Resistance Initiative (AHRI)

Alphabet cross-resistance in South Australia

Alarming herbicide resistance news has come out of South Australia. A population of ryegrass from the Eyre Peninsula, SA has been confirmed resistant to all of the pre-emergent herbicides – Avadex, Arcade, Trifluralin, Propyzamide and Sakura, as well as two lesser-known herbicides. It was sampled in 2014 just two years after the release of Sakura in Australia. You guessed it, metabolic cross-resistance is at play. What’s most concerning is a random survey in the South East of SA found many more populations of ryegrass with multiple cross-resistance to a range of pre-emergent herbicides. The perplexing thing is that there’s no predictable…

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Australian Herbicide Resistance Initiative (AHRI)

GST – a tax on herbicide molecules

When you buy a birthday cake, the goods and services tax (GST) makes the cost of the cake bigger.  If only Mr Hewson could have explained it so succinctly he may have been Prime Minister! There’s another type of GST in plants that do the same thing to herbicide molecules. It makes them bigger and then the whole thing gets smashed to pieces. The GST in plants are enzymes called glutathione-S-transferase.  In other words, they join or transfer the big molecule glutathione onto other molecules. Click through to learn more!

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Australian Herbicide Resistance Initiative (AHRI)

Digging deep into 2,4-D resistance

Synthetic auxins might be the oldest kids on the herbicide block but that doesn’t mean they are well understood. In fact, there are very large knowledge gaps that researchers like AHRI’s Dr Danica Goggin are trying hard to fill in a bid to find ways to overcome resistance to this herbicide group in weeds such as wild radish.

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