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Australian Herbicide Resistance Initiative (AHRI)

On a good thing? Don’t stick to it! – the Director’s Cut

Written by: Cindy Benjamin

Welcome to the highlight reel of AHRI’s recently released blockbuster – ‘Don’t stick to it!’. Set in the labs, glasshouses and fields of this world-leading research powerhouse, and featuring renown giants of the herbicide resistance world – Powles, Busi, Yu and Owen, this latest exposé will have you seriously impressed!

‘Don’t stick to it!’ delves into five years of ground-breaking scientific discovery and its value to Australian farmers in their epic battle against profit-sucking weeds.

Since the inception of the Australian Herbicide Resistance Initiative (AHRI) in 1998, researchers based at the University of Western Australia have been leading the way in gaining deeper understandings of resistance evolution, resistance mechanisms and resistance management. The driving force behind their research is the need to preserve herbicide efficacy while also devising non-herbicide strategies to achieve sustainable weed management in Australian cropping systems.

The recently-completed 5-year research program was the fifth GRDC investment in the work at AHRI. Led by Professor Stephen Powles for the first few years, the project concluded under the directorship of Professor Hugh Beckie.

Prof Beckie is pleased to announce that the AHRI research program will continue to provide cutting edge crop and weed management research with renewed investment from GRDC secured to 2025.

The AHRI team in 2019.

Podcast

Resistance evolution   

Director Beckie says knowing how key weeds are responding to herbicide use on-farm spurs the team on to find the key mechanisms for resistance and to develop and test agronomic and herbicide strategies to combat their evolution and spread.

AHRI’s regular large- scale random field surveys are led by Dr Mechelle Owen and seek out trouble-makers Ryegrass, Wild Oats, Barley Grass, Brome Grass, Wild Radish and Fleabane lurking in 500 WA cropping fields (last survey in 2015). Detailed testing of the weed seed collected in the Western region shows the march of herbicide resistance across the landscape and importantly, identifies which herbicides continue to be effective.

Dr Mechelle Owen

The Western region survey results are compared with similar surveys being conducted in the GRDC Southern and Northern regions under a separate GRDC tender, the National Surveillance Project. The plant materials were used in various AHRI experiments and studies, and the resistance survey data is of considerable value to the agrichemical industry, agronomists and other advisers as well as growers.

While Dr Owen investigates the response in the field, Dr Roberto Busi leads the charge on assessing the resistance risk of new site-of-action herbicides and developing herbicide technologies, such as novel mixtures, for managing existing or new herbicide-resistant weed biotypes.

Dr Roberto Busi

“Dr Busi’s program identifies agronomic and ecological factors impacting herbicide efficacy,” says Director Beckie. “To better understand the dynamics of herbicide resistance selection and the spread of weed resistance, AHRI research includes the use of simulation modelling as an initial test of scientific hypotheses. Modelling provides valuable insights into weed resistance evolution and the use of integrated weed management tactics that can mitigate and manage herbicide resistance on-farm.”

Wild radish random AHRI survey of Western Australia

Has herbicide resistance in ryegrass in WA plateaued?

Mixing herbicides wins again

Luximax gets its own NEW box

GST – a tax on herbicide molecules

Resistance mechanisms

Delving into the unseen world of the molecular and biochemical drivers behind herbicide resistance in weeds is Dr Qin Yu, heading up AHRI’s internationally acclaimed genetic research team.

Director Beckie says establishing the biochemical and molecular genetic basis of novel herbicide resistance in Australian major crop weeds, and ensuring the information is widely disseminated, is a foundation stone for the evolving story explored in ‘Don’t stick to it!’.

“AHRI is very proud to have reported the first global case of HPPD inhibitor resistance in wild radish, which was based on the first report of HPPD resistance in Australia, and the first global report of metabolism (Aldo-keto reductase) as a glyphosate resistance mechanism in weeds,” he says. “These are very significant findings and represent an important contribution to the understanding of herbicide resistance mechanisms, which in turn opens new doors for the development of strategies to manage herbicides and minimise resistance.”

Dr Qin Yu & Dr Heping Han

World’s first metabolism-based glyphosate resistance discovered

Group H (HPPD) resistant wild radish

Resistance management

The colourful, but solid scientific background of herbicide resistance might have you ready to throw your hands in the air and shout with despair, but for the team’s determination to devise, test and promote practical solutions to the problem.

“At the end of the day AHRI research is all about finding solutions that growers can implement in the field to keep herbicides working effectively while maintaining profitability,” says Director Beckie. “We are very proud to have been involved in the harvest weed seed control and the new targeted-tillage implement journey over the past decade. This work began in AHRI under the leadership of Dr Michael Walsh, who now leads the weed research team at the University of Sydney.”

AHRI’s focus on agronomic strategies such as increasing crop competitiveness to minimise the impact of weeds on productivity while driving down the weed seed bank pays off with ‘More crop, fewer weeds’ being the catch-cry of the movie.

Along the way, a suite of decision support tools is revealed, allowing growers to pre-test the impact of herbicide and non-herbicide tactics on populations of the villain Grass Brothers – Rye, Brome and Barley.

What’s the cost of harvest weed seed control for YOU?

Hoe, hoe, hoe and away weeds go!

What’s the sticking point? Better pre-em efficacy in stubble retention systems

Extending the message

Cheering the researchers on at every turn is the Communications Team, led by Lisa Mayer and Jessica Strauss and now with the help of Communications Officer Shannen Barrett. As the research is detailed in scientific journals around the world, the communications team breaks it down into digestible messages that inform decisions of growers and their advisors.

Communications Lead Jessica Strauss, Centre Manager Lisa Mayer, Communications Officer Shannen Barrett

Director Beckie applauds the efforts of the whole AHRI team to engage with over 3000 individuals in the agricultural and weed management sector with regular updates through AHRI Insights alone, and through social media, podcasts, webinars, videos, online courses, events and face-to-face presentations.

Unlike the Rocky, Terminator and Fast & Furious movie series, AHRI 6 is set to be even better than AHRI 5, so stay tuned!

You can keep up with the latest developments through AHRI Insights, AHRI Snapshots podcasts and AHRI videos, all on the AHRI website or subscribe to our newsletter to have the news delivered to your email address once a month.

A brief history of AHRI.

Featured papers

Pyroxasulfone resistance in Lolium rigidum is metabolism-based

Cinmethylin controls multiple herbicide-resistant Lolium rigidum and its wheat selectivity is P450-based

Rotations and mixtures of soil-applied herbicides delay resistance

Evolution of resistance to HPPD-inhibiting herbicides in a wild radish population via enhanced herbicide metabolism

Aldo-keto reductase metabolizes glyphosate and confers glyphosate resistance in Echinochloa colona

The research summarised here was made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC.

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