mechanisms

September 10, 2019

Is there an invisible gorilla in your paddock?

Huan Lu’s been investigating a population of wild radish that has the infamous Ser-264-gly mutation. This is the target-site mutation that is behind TT canola and makes wild radish highly resistant to PSII-inhibiting herbicides like atrazine and, to a lesser extent, metribuzin.

But, he wondered if there was more to this resistance than first meets the eye. Does focusing on the strong 264 mutation mean that we could fail to identify other important resistance mechanisms?

July 26, 2019

Crops are doin’ it for themselves

We answer a few poignant questions in this insight, including: ‘Can crops do more of the heavy lifting when it comes to weed control than modern farming methods have allowed them?’

or

‘Have we tried so hard to protect crops from weeds that we have forgotten that they have innate mechanisms to ‘stand on their own two feet’ and ‘do it for themselves’?’

A series of important studies into the practical implications of harnessing the crop’s ability to defend itself against weeds are starting to produce important results, leading to improvements in farming practice and the development of new cultivars.

June 17, 2019

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.

April 15, 2019

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.

March 19, 2019

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 from ARC and Nufarm.The short story here is that resistance in wild radish to 2,4-D is not metabolic resistance.  The longer story is much more interesting and explains how this works in wild radish, and how 2,4-D tolerance in grass plants is (partially) through a metabolic process.

February 19, 2019

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…

October 19, 2018

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.

October 8, 2018

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.

September 7, 2018

‘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.   

August 30, 2018

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 cross-resistance pattern.