Fighting Global Weed Resistance
Fighting Global Weed Resistance

Breaking the Cycle Breaking the Cycle

The development of herbicide resistant weeds is a global concern. Researchers, inventors and farmers around the world are joining hands to counteract this serious problem. Their key strategy: knowledge exchange.

These greenhouses are special – they are full of weeds. The pots are neatly lined up in rows and the plants are sorted by size and species. Harry Strek, weed control biologist at Bayer and the multicultural team of researchers tend to them. But they also do much more: The scientists compare weeds that have been treated with herbicides with untreated weeds and examine their genetics in the laboratories located next door. “We are trying to better understand what causes herbicide resistance in weeds and are searching for new methods and strategies to fight the problem,” explains Strek. Their results will help farmers around the world.

The researchers’ work takes place in the facilities of the newly established Weed Resistance Competence Center (WRCC) in Frankfurt, Germany. The site can already look back on over a decade of expertise and research in weed resistance and has re­cently been rebranded as the WRCC, Bayer’s global reference center for weed resistance management. The core activities of its fourteen full-time personnel cover three areas: understanding weed resistance mechanisms and their evolution­ in the field; developing and testing new weed control strategies; and sharing Bayer’s knowledge and weed control solutions with the entire value chain. “Bayer clearly recognizes the threat that herbicide resistant weeds pose to agriculture,” says Strek, the facility’s Scientific Director. Besides the work the group does on site in Frankfurt, a lot of their activities are also external. “We interact with researchers at Crop Science’s headquarters in Monheim and in countries around the globe, but also with scientists, regulators, distributors and farmers around the world,” says Strek.

Harry Strek, weed control biologist and the team of researchers at the Weed Resistance Competence Center of Bayer CropScience in Frankfurt keep close contact with Bayer CropScience’s headquarters and with scientists, regulators, distributors and farmers in countries around the world.

Herbicide resistant weeds are a problem that concerns every party involved in growing a crop but ultimately a farmer alone has control over what goes on in his field.

Harry Strek, weed control biologist at the Weed Resistance Competence Center of Bayer in Frankfurt
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different weed species have evolved resistance to common herbicides, which can severely impact yield up to 100 percent. (Status: March 2016)

One of the WRCC’s international cooperation partners is the Australian Herbicide Resistance Initiative (AHRI). Its headquarter is located at the University of Western Australia in Perth. Prof. Stephen Powles directs the initiative and is widely known as a respected leader in Australian and global agricultural circles. He has seen the resistance problem looming on the horizon for many years: “Herbicide resistance started in Australia around 30 years ago,” Powles remembers.

In the past, Australian agriculture mainly consisted of extensive areas of pastured landscapes with millions of sheep and smaller cropping enterprises. As the production ­of staple crops increased and the importance of animal husbandry declined, the growing numbers of crop fields were invaded by weeds such as ryegrass, previously planted for pasture: “Farmers treated huge areas with herbicides but used crop protection products with the same mode of action too often. So they evolved resistance in a short period of time,” Powles adds. Annual ryegrass is one example that easily evolved a resistance and many other major weeds are now also resistant to herbicides that once provided good control. Consequently, Powles and Strek, and their teams, are putting great effort into researching new strategies to manage herbicide resistance and slow its evolution. And from their perspective, the interactions between the AHRI and the WRCC are very advantageous: “Bayer is one of our linkage partners and we are in constant dialogue with each other. We use research expertise available at Bayer that we couldn’t possibly reproduce here and vice versa,” says Powles. Both institutions also attach great importance to sharing their research results with a wide audience: “We invest 30 percent of our budget in communication. There is no point in doing research if its results are not communicated,” says Powles.

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Knowledge Exchange

Harry Strek in Frankfurt has a similar opinion: “We want to deliver consistent messaging based on sound scientific results. Farmers need to understand that herbicide resistant weeds are a problem that concerns every party involved in growing a crop but ultimately that the farmer alone has control over what goes on in his field.” Strek regularly visits farmers worldwide to share his experience face-to-face and gain valuable local insights. During these visits he and his team translate their research results into concrete and clear messages: “We want farmers to understand the importance of what they can do to make farming and controlling weeds a more sustainable practice. This includes following a good crop rotation and applying varying herbicides and supplementing this with non-chemical weed control measures. Because always using the same mode of action greatly increases the potential for developing new resistance,” Strek summarizes.

Diversity is key and good agronomy is essential to sustaining effectiveness.

Craig White, Australian Lead for ­Integrated Weed Management Projects

Bayer also communicates with farmers all over the world via its local representatives and advisors. Craig White is one of the company’s Technical Advisors in Western Australia. He and his colleagues embody a standing link between the WRCC in Germany and farmers Down Under: “We send weed samples from Australian fields to the WRCC-staff in Germany that examine the material. After that, the results are sent back to us, and we translate the data into treatment recommendations for the farmers,” he explains. In most cases, his advice distils down to this: Using healthy crops to outcompete the weed, employing regular crop rotation and tillage and applying herbicides judiciously. “Diversity is the key and good agronomy is essential to sustaining the effectiveness of existing herbicides. The days of just being able to spray and forget are over. We need to be smarter about our use of precious chemical resources. It’s technology and brains combined,” says White.

Australian Ingenuity 

Australian ingenuity is also contributing to this concept of using diversity to tackle weed resistance. One striking example is farmer and inventor Raymond Harrington. He has successfully approached the weed resistance problem with an entirely new idea – the Harrington Seed Destructor or “HSD”. The enormous machine weighs over five tons and has a height of 3.2 meters. It is towed behind a combine harvester and crushes the weed seeds before they return to the soil and can germinate the next season. “The HSD is actually very simple. It’s all about combating the weeds in a different part of their life cycle. If we can break the weed seed cycle, then we will break the weeds,” says Harrington. Stephen Powles and the AHRI have also been collaborating with Harrington since 2005 and have supported him, with funding from the Grains Research and Development Corporation (GRDC), to commercialize the machine. It has already reached the US and Canadian markets and both men hope it will contribute across borders: “This is a global war on weeds and farmers need everything they can get to win their battles,” says Harrington.

Raymond Harrington is the inventor of the Harrington Seed Destructor – a mechanical contribution to combat weeds. 

Weed Resistance

Amount of herbicide resistant weed species.
Source: International Survey of Herbicide Resistant Weeds

Another Australian contributor to the international effort is Tim Scott. He manages a farm in Arthur River, in the southwest of Western Australia and also works as an agronomist at Agvivo, an agricultural consulting company. “We develop farm management plans together with the growers by taking the weed populations in their paddocks and their use of herbicides in the past into account,” explains Scott. “Based on this analysis, we help the farmers decide which herbicide to use in that particular year.” The agronomist has done a lot of resistance testing with growers in the last couple of years and his work has been invaluable to get a better idea of what the local farmers are dealing with in terms of herbicide resistance. He even has a triumph to report: “Last year was regarded as a landmark year because the level of ryegrass resistance against one herbicidal compound decreased for the first time in five years. This is a trend that we must continue to support.”

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