Australian professor shares herbicide resistance knowledge during WSU visit

The key to helping weed science researchers in Washington State University’s College of Agricultural, Human, and Natural Resource Sciences (CAHNRS) battle herbicide resistance could come from Down Under.

Michael Walsh, an associate professor at the University of Western Australia, spent a week at the WSU Pullman campus this fall, discussing herbicide resistance and weed seed control with farmers in the surrounding region and giving a seminar to scientists in WSU’s Department of Crop and Soil Sciences. Walsh thinks impact mills—physical weed seed control systems that attach to combines and are widely used in Australia—could hold promise for the Pacific Northwest.

A man in a black jacket and khaki pants stands next to a large green combine, pointing to it.
Michael Walsh explains how impact mills are used on combines during a meeting of growers, WSU weed science researchers, and others at a farm near Pullman.

Drew Lyon, professor and endowed chair in small grains Extension and research, weed science, invited Walsh to WSU. Lyon describes Walsh as the “international expert” in harvest weed seed control.

“Having an international visitor isn’t common, and it allows us to increase the visibility of the harvest weed seed control concept,” Lyon said. “It’s valuable to WSU to have an expert visiting from so far away. People tend to pay more attention when they hear that.”

Australia has fought herbicide resistance in weeds since the early 2000s, forcing growers and researchers to develop new systems and techniques for their small grains cropping systems. These could also be successful in the Inland Northwest.

“Australia has been further ahead of us with resistant weed problems,” Lyon said.

Walsh’s Pullman stay was part of a Fulbright scholarship visit to the U.S. that includes three-month stops at Kansas State University and Texas A&M University.

Walsh was drawn to studying herbicide resistance because of the global challenge and learning experience it presents. While abroad, he hopes to share his knowledge with U.S. researchers and explore opportunities to expand weed seed control methods.

“I became enthusiastic about studying these systems when I started talking to farmers and saw the difficulties they faced and how it affected their operations,” said Walsh. “It’s been a great experience as a researcher to work with those individuals.”

The scientists met when Lyon was an assistant professor at the University of Nebraska and Walsh was studying for his PhD in agronomy at the University of Wyoming. They reconnected in 2012 when Lyon came to WSU and started researching Italian ryegrass, a non-native, herbicide-resistant weed that thrives in higher rainfall areas of eastern Washington like the Palouse. The two have since collaborated on projects including a Pacific Northwest Extension bulletin on harvest weed seed control.

Lyon hopes Walsh’s visit will support a mutually beneficial sharing of knowledge between WSU and Australia for years to come.

“That’s how science works best,” Lyon said. “Smart people exist all over the world, and it comes down to talking with them, getting new ideas, and seeing how they translate.”

Walsh has been to the Pacific Northwest a few times before, and said he hoped to gain a sense of how attitudes toward novel methods of weed seed control have changed over time.

Current practices for controlling herbicide resistant weeds include smart herbicide usage, crop rotation, tillage, and impact mills.

A man in a black jacket puts his hand inside an impact mill on a green combine as a woman and a man look on.
Michael Walsh discusses the intricacies of the impact mill system with meeting attendees.

Herbicide resistance, which can take anywhere from three to five years to develop, is determined by a weed’s genetic variability—the more genetically diverse the weed population is, the more likely it is to become resistant. Growers in Australia have learned that if they use harvest weed seed control methods like impact mills in tandem with herbicides, they can substantially prolong the life of herbicides. Farmers in the Palouse region may be able to follow their example.

Herbicide resistance presents many challenges, but Walsh remains positive.

“The opportunities are huge,” Walsh said. “We have a lot of work to do, but it will be worth it.”

Lyon, meanwhile, looks forward to future partnerships with Australia and other countries that can help students and further WSU weed science research.

“CAHNRS and WSU want to increase international collaborations from a research standpoint and an educational standpoint,” he said. “We would like our students to have more experiences overseas. The more of these alliances we can develop, the more likely we are to foster worldwide collaborations.”