Montana State scientists study how wild oats become resistant to herbicides

With new funding from the U.S. Department of Agriculture, scientists in Montana State University’s Department of Plant Sciences and Plant Pathology will seek to fill knowledge gaps surrounding an agricultural weed that has caused problems for Montana producers for decades.

Jennifer Lachowiec, an associate professor in MSU’s College of Agriculture, received two grants from the USDA’s National Institute of Food and Agriculture totaling more than $900,000 to study how wild oats develop herbicide resistance and to explore management techniques for the weed.   

Lachowiec’s work blends several disciplines including plant genetics, remote sensing and molecular biology. The project, which includes collaborators William Dyer and Barbara Keith in the Department of Plant Sciences and Plant Pathology and Tim Seipel and Paul Nugent in the Department of Land Resources and Environmental Sciences, aims to give agricultural producers recommendations for either precise herbicide applications or alternative management practices.

“Wild oats are a major weed pest in Montana,” said Lachowiec. “It's a problem not just for our local farmers, but also for the people they serve. They don't want to lose some of their productivity due to wild oats.” 

Wild oats can be a large problem when in competition with barley, a commodity in which Montana is the national leader, making the research particularly applicable closest to home. Approximately 920,000 acres of barley were planted in Montana in 2024, according to the USDA’s National Agricultural Statistics Service, which releases annual reports for major crops. Montana has been the top barley-producing state in the nation for several years, and approximately a quarter of the state’s total barley acreage in 2024 was planted with MSU-developed varieties of barley used for malting, forage and feed.

Lachowiec and the other MSU scientists are examining a variety of qualities in wild oats. Past research in Dyer’s lab revealed that the pigments in leaves of herbicide-resistant plants make them appear darker green in color than those susceptible to herbicides. Upon that discovery, the researchers began using drones to take images of fields, looking to see if the same color pattern would emerge in fields that they observed in the lab.

“If we observe plants in the field that we know are resistant or not, can we see that difference?” said Lachowiec. “A second big aspect is working with farmers to have them take pictures of the wild oats that they see in the field, to also analyze the color of the weeds and get a perspective of what people are encountering.”

With continued precision research involving drone imagery and plant color data collected at different wavelengths, Lachowiec said the ultimate hope is to develop a tool which farmers could use to more easily identify resistant weeds without having to collect their seeds and send samples to a lab for testing. Producers can aid in the research themselves by sending images of wild oats on their own land, which the scientists can then analyze. MSU Extension specialist Tim Seipel has worked to communicate with farmers around the state to learn more about the issues they are facing with wild oats. Interested farmers can find resources and information on research collaborations on the website for Seipel’s Cropland Weed Ecology Lab. 

“We hand out color calibration cards to deal with whether you take a picture on a cloudy day versus a sunny day, since those plants will look different,” Lachowiec said. “If you put the color card in the background, we can calibrate the pictures. And then with those calibrations, we'll be able to compare the color of plants directly between the different locations and different farms. And that will enable us to have a better perception of what the wild oats look like across the state.”  

Further scientific studies will explore the effectiveness of herbicides in different environments. While many herbicides are better at controlling weeds in warmer conditions, Lachowiec said wild oats show the opposite trend, becoming more resistant in hotter weather. The MSU team will aim to identify how wild oats become more herbicide resistant in warmer climates, using genetic mapping and gene transcription to identify cellular mechanisms for resistance and potentially testing new tools that may target those mechanisms.

Lachowiec said that wild oats have been a concern in Montana since farmers have been growing small grains, and that their degree of resistance to herbicides has changed significantly in recent years. Because resistant wild oats are now found more widely in Montana and are frequently resistant to all common agricultural herbicides, applying those products where they won’t work costs producers unnecessary money and can cause further herbicide resistance to develop, as well as potentially harming other, beneficial plants nearby.

“By understanding how herbicide resistance can be induced by stressful environments, like high temperatures, we can inform the development of new tools and strategies to overcome weeds and prevent ineffectual use of herbicides,” said Lachowiec. “This will contribute to better environmental health and economic outcomes for agricultural markets.”