In an ideal world, combines should have a built-in mill that destroys weed seeds on the fly, says Adam Davis, a U.S. Department of Agriculture weed scientist.
A couple of years ago, in collaboration with the University of Illinois’ mechanical engineering department, Davis helped develop prototype mills that could be attached to combines.
He said it requires only a minimal amount of physical crushing or damage to the seed to hinder the weed’s reproductive process.
“If you make even minor nicks to their seed coat, the microbes in the soil are able to decay those seeds very quickly.”
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While he’s convinced that such mills would destroy seeds and reduce weed populations, Davis said American combine manufacturers haven’t been willing to implement the idea.
“All I’ve got is proof of concept…. By controlling that weed seed return, reducing inputs to the seed bank and longevity of seeds that enter the seed bank, is the number one thing that will reduce weed population growth rates,” Davis said. “I think they (manufacturers) find it interesting, but the market signal just isn’t there yet.”
American Midwest growers might be more interested a few years from now because a herbicide resistant weed from the southern U.S. is moving into the region, he said.
A few Illinois soybean growers have reported palmer amaranth in their crops this summer.
“This is a weed that’s going to be an economic game changer, in terms of the levels of yield loss it’s able to create,” Davis said.
“It’s very difficult to control chemically. This may be the type of thing that forces the issue … to think about seed collection in the crop.”
University of Saskatchewan professor Steve Shirtliffe says kochia might be a prairie weed to control this way.
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