Source: University of Illinois

By Stephanie Henry

It’s a piece of equipment that probably isn’t on many Midwest farmers’ radars at this time, but could eventually be a new tool against the growing herbicide-resistant weed problem, says a University of Illinois crop scientist.

With the effectiveness of many herbicide options being compromised due to the evolution of weed resistance, and no new products on the immediate horizon, Aaron Hager says now is the time to look at non-chemical tactics that can be integrated into a management system.

Hager and Adam Davis, a crop scientist at the University of Illinois and USDA, were recently awarded funding from the USDA to bring the Harrington Seed Destructor, which was developed and is used in Australia, to the University of Illinois South Farms. The seed destructor is a portable mill that attaches to the combine. As the combine collects the chaff at harvest, the pull-behind mill pulverizes the weed seeds, preventing them from growing into new plants the following spring.

The idea is to control the weeds at harvest.

The seed destructor will be on display at this year’s Department of Crop Sciences’ annual Agronomy Day on Thursday, Aug. 20, on the University of Illinois South Farms. Hager and Davis will be on hand to answer questions about the machine.

Hager said while Australia’s problem weed species are different than those in central Illinois, growers in that country have seen similar resistance evolution problems, particularly with ryegrass. However, Australian farmers using the seed destructor are seeing some success. The company that manufactures the machine reports that the seed destructor destroys at least 95% of annual weed seeds.

“Their most problematic species in Australia is ryegrass. Here we talk about multiple resistance of waterhemp, but truth be told, theirs is worse,” Hager says. “Based on the success that they’ve seen in Australia, we would be confident in saying that, on some of our larger-seeded species, it would be effective. We need to get a better feel of how it will work on these smaller-seeded species.”

Davis has designed a research project at Urbana to evaluate the impact the machine could have on herbicide evolution in waterhemp. Davis says they hope to find out if they can control herbicide-resistant waterhemp populations in a given year, and if they can reduce the increase of herbicide resistance genotypes in a field over time.

“It’s not Palmer amaranth, but waterhemp is certainly a problematic species that we have. It is similar in seed size to Palmer amaranth,” Hager explains.

Hager says he expects the project could take 2-3 years before they have the needed data and an understanding of how effective the seed destructor will be in reducing seed return to the soil. The experiment will also look at how to integrate the machine into a system with other management practices.

“We’ll continue to need herbicides,” Hager says. “Hopefully this will be something that adds another tool by using a technique that we haven’t used much before.”

For now, Hager says they are on a wait-and-see basis to determine how the machine will work against Midwest weed species. Hager, Davis and their crew are still working to retrofit the seed destructor to a combine to begin the planned research trials.

“For us, it’s new,” he says. “We’re running out of effective herbicide options, and what we see now with resistance may not be the same in 5 or 6 years. It could be much worse. For years, we’ve said that we need to stop controlling weeds and learn how to manage them. This falls into the management idea. Based on what the data will tell us, it could be something very effective.

“Hopefully we’ll get that established, and it will be something that the industry will take from there.”

For more information about this year’s Agronomy Day where visitors can learn more about the seed destructor, visit