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Australian Herbicide Resistance Initiative (AHRI)

Blog: AHRI insight

Australian Herbicide Resistance Initiative (AHRI)

Pre-emergent herbicides in stubble – strike or foul?

Ever tried walking out onto a 10-pin bowling alley? It’s generally not pretty, often resulting in a rapid and undignified descent to ground level…But that’s just what we need to get pre-emergent herbicides to slide off stubble and into the soil, which can be difficult in higher residue systems. Rainfall is obviously a key driver in leaching herbicides from stubble before they dissipate, but as we all know rain can be an unpredictable beast. Fortunately, research has shown that some pre-emergent herbicides require far less rainfall to move off stubble and into the soil where they can control germinating weeds. 

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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)

The significant weed science research stories of 2018

Written by: Jessica Strauss, Peter Newman, Cindy Benjamin, Kirrily Condon  It’s been a big year for AHRI. Former AHRI Director, Stephen Powles retired from the position earlier in the year, with Professor Hugh Beckie from Canada taking on the role.  We also saw the opening of the GRDC-funded Agronomy Laboratory at the University of Western Australia. Research is at the core of what we do though and we didn’t do that in halves this year either! Not only did AHRI produce significant papers, but other weed science groups nationally also made important discoveries. Harvest Weed Seed Control continues to see gains in uptake,…

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Australian Herbicide Resistance Initiative (AHRI)

Ryegrass seed set control in canola – timing is everything

Stopping ryegrass seed set pre-harvest in canola is all about timing. Sometimes the timing window lines up, other times it does not. Glen Riethmuller, DPIRD Merredin has a knack for choosing the most difficult, most labour intensive research trials to undertake. Between 2010 and 2013 he, along with Abul Hashem and Catherine Borger investigated ryegrass seed set control pre-harvest in canola. They investigated the practice of spraying under the swather as canola is windrowed for harvest compared to crop topping (desiccation) spraying over the top of the canola.

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Australian Herbicide Resistance Initiative (AHRI)

Behind every successful HWSC approach is crop competition

Harvest weed seed control (HWSC) is often described as the holy grail of weed management, but we all know how the saying “Behind every successful person…” ends. There’re usually more factors at play than just the individual, whether that be lots of coffee or a great support team. The same goes for HWSC. Research by Michael Walsh from the University of Sydney and John Broster from Charles Sturt University has shown that crop competition plays an important support role in the success of harvest weed seed control. Click through to learn more!

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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)

Are ‘pre-ems and crop competition’ the ‘wine and cheese’ of weed control in canola?

Wine and cheese. Strawberries and cream. Crop competition and pre-emergent herbicides. Ok so the last one doesn’t quite have the same ring about it but they really do go together nicely. Combining a competitive canola variety with pre-emergent herbicides has proven to be an effective strategy for reducing annual ryegrass seed set. Recent trials showed that with effective pre-emergent herbicides, a competitive hybrid canola variety can reduce ryegrass seed set by 50% compared with a less competitive open-pollinated (OP) variety. That’s impressive. But should we tar all OP varieties with the same brush?

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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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