The next big thing in weed management will likely come at harvest.
While chemical control of weeds is common before and during the growing season, University of Missouri weed scientist Kevin Bradley says farmers need alternatives because of resistance. Missouri has 14 weed species that show resistance to today’s herbicides. Resistance to multiple modes of action are increasing. To combat weeds and protect the future of chemical technology, farmers should look to manage weed seed at harvest.
Harvest weed seed management started a decade ago in Australia. The country had a ryegrass resistant to all herbicides on the continent.
Then, Australian farmer Ray Harrington developed a machine known as the Harrington Seed Destructor that grinds small weed seeds, rendering them unable to germinate. It is a pull-behind piece of equipment with a high price tag — around $100,000. But over the years, agriculture equipment companies started looking at a way to incorporate similar systems inside combines. And University of Missouri weed scientist Kevin Bradley plans to test one such device this year.
Research ready
Currently, a Case IH 8250 combine is being outfitted with a Seed Terminator. The Australia-based Seed Terminator is a one-pass weed-control system designed to reduce the amount of seed put back onto the ground at harvest.
It uses a multistage hammer mill placed inside the combine that grinds seeds into dust before exiting out the back. The attachment appears to work in Australia, as tests there show more than 95% of seed leaving the Seed Terminator is not viable.
Bradley wants to know if it can produce the same results in the U.S. He needs help from farmers. “We want to test this in the field,” he says. “We will harvest your crop for you.”
On-farm trials
Bradley is looking for a few farmers with 60 to 80 acres of weedy soybeans within a 100-mile radius of Columbia, Mo., to test the Seed Terminator. He says university researchers will harvest soybeans with the Case IH and a 35-foot header, turning the Seed Terminator on and off across the field.
“We want to see what is exactly coming out of the back end of that combine,” he notes. He will track seed population and viability.
Farmers wanting to cooperate can contact Bradley through their regional MU Extension agronomist. There is an MU Extension office in every county.
Harvest add-on reduces weed seed
The Seed Terminator is in its fourth year of production. The brainchild of Nick Berry, a farmer’s son and mechanical engineer, and Mark Ashenden, an Australian businessman.
Currently, the Seed Terminator is sold only in Australia. The University of Missouri is one of the first to have access in the U.S.
Here are a few specifics from the company website regarding how the hammer mill works to kill weed seed:
• Multistage hammer mill uses a combination of shearing, crushing, attrition and high impact to kill weed seeds.
• It has three stages of screens to classify material for size.
• Chaff material and weed seeds must be smashed small enough to fit through each stage of screens. The process uses large openings that progressively get smaller.
• Multiple stages ensure high capacity while maintaining pulverization to consistent level at a range of rotational speeds.
• It requires 80 to 100 hp.