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Professor Stephen Powles

Fighting Global Herbicide Resistance


Herbicide Resistance is a global challenge. Professor Stephen Powles, Director of the Australian Herbicide Resistance Initiative (AHRI), discussed this issue with Liam Condon, Member of the Board of Management of Bayer AG and President of the Crop Science Division, at the Weed Resistance Global Symposium in Paris.


Prof. Powles' expertise ranges from the fundamental science on the evolution and molecular basis of herbicide resistance through applied agronomic research and management. Within the last 32 years, he has strongly influenced Australian and international thinking on sustainable herbicide usage by reducing herbicide reliance and increasing diversity in agro-ecosystems.

Liam Condon Weeds threaten our global food supply. They harm enough crops to feed one billion people. The total losses from weeds worldwide are estimated at 13.2 percent of agricultural production, worth more than 55 billion euros a year. We can control weeds with herbicides, but increasing herbicide resistance on a worldwide level is a huge problem. It can only be solved through a holistic and sustainable approach – based on knowledge exchange, collaboration and innovation. That is why we at Bayer are striving together with leading scientists and international institutions to jointly develop new solutions that help farmers worldwide to combat herbicide-resistant weeds. For example, we are delighted to be working together with you, Steve, as a world-renowned and highly accomplished herbicide expert. You and your organization, the Australian Herbicide Resistance Initiative (AHRI), are fantastic partners for us.


Stephen Powles Actually, we need to work together because we are in the same boat. But we also find our collaboration with Bayer to be very advantageous. For example, our AHRI Team profits from close interactions with Bayer’s Weed Resistance Competence Center in Frankfurt. It is very valuable that we can use each other’s research expertise, which we couldn’t possibly reproduce in our own countries. In fact, we have an Australian Research Council funded project on the mechanisms of resistance in which Bayer is a linkage partner. Also, events like this Weed Resistance Global Symposium offer a forum for discussion regarding practical Integrated Weed Management solutions.


Liam Condon Yes, these exchanges of experiences are crucial in order to develop better solutions that are needed to ensure we can feed not only today’s population, but also the expected 9-10 billion people by 2050. Weeds are real and evident threats to farmers’ harvests. I remember very well the first time that I saw the ‘Palmer amaranth’ weed out in the field – Palmer amaranth is able to grow five centimeters per day, ending up at four meters tall and able to produce 1.8 million seeds per season. What crop plant could withstand such a strong adversary?


Stephen Powles Indeed. Weeds have been persistent robbers of food for at least 10,000 years of agriculture. They have demonstrated their ability to survive and persist despite human efforts. Our new joint approaches and the decisions that we make will influence world food supply. Our objective is more food through fewer weeds – but sustainably. By now, we discovered one of the most important lessons: Herbicides are superb weed control tools. They are effective, cheap and easy to use – but also easy to overuse! Multiple resistant weeds are telling us that herbicides alone are not sustainable. The golden age of herbicides, where the weeds could easily be controlled, is over. So today we cannot overly rely on them. We can only win this battle if we use these precious tools more wisely than we have in the past. And we have to apply a combination of chemical and non-chemical crop protection – such as smart crop rotation, harvest weed seed control and digital farming tools – in order to tackle weed resistance and sustain herbicides in the long run. Diversity is the key.

A black and white photo of a man in a suit.
Ensuring diversity in the fight against weed resistance is the only sustainable way forward.
Stephen Powles
Professor at the University of Western Australia and the Director of the Australian Herbicide Resistance Initiative (AHRI)

Liam Condon I completely agree. A diversity of approaches is key to ensuring a sustainable intensification of agriculture. For this purpose, we currently invest annually more than one billion euros in crop science research and development with a strong focus on our integrated toolbox, combining chemical and biological crop protection products with modern breeding technologies and trait research. Science and modern technologies such as digital farming play a vital role in shaping the future of farming. Digital Farming solutions can help growers gain a better understanding of what’s going on in their fields and allow them to make better and faster decisions. Precise, real-time crop monitoring data and soil health analyses are examples that can enhance decision making and help ensure a higher focus on sustainability. We are excited about the possibilities such new technologies deliver in the fight against resistant weeds.


Stephen Powles That is the right approach. Diverse techniques in the fight against weed resistance are the only sustainable way forward. Furthermore, diversity needs communication. Connecting growers, the industry and the scientific community requires traditional and new ways of interaction, such as social media. Our research results have to be distributed across all communication channels: To the growers, the agricultural industry, the advisors and the scientific community. That is why in our research team, we invest 30 percent of our budget in communication.


Liam Condon Great point. As an industry we probably under-invest in communication. Engaging with the public and everybody involved in agriculture is essential to bring our messages across. We at Bayer are placing a stronger emphasis on doing this better through a more integrated media mix – ranging from our company publication, ‘Farming’s Future,’ to corresponding digital and social media activities, and also educational approaches. We want to encourage societal dialogue and raise awareness of the need for new innovation and technology.

A black and white photo of a man in a suit.
Science plays a vital role in shaping the future of farming.
Liam Condon
Member of the Board of Management of Bayer AG and Head of the Crop Science Division

Stephen Powles Yes, it is vital that we share our key findings with the end users to create consciousness for herbicide resistance and a change of behavior. There is a role for everybody in this to manage resistance and to providing food for an ever-growing world population. Together, we are going to defeat weeds through science, technology and understanding evolutionary principles. The time to act is now!


The AHRI is a research leader in herbicide resistance in Australian cropping. It is focused on sustainable farming and weed control. With headquarters at The University of Western Australia, the multi-disciplinary team’s research activities range from understanding the biology and control of major weed species through the development of agronomic and herbicide management strategies. Fundamental research occurs at the biochemical and molecular level.


For more information, visit Australian Herbicide Resistance Initiative.


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