Production Blog

Dirty Not-So-Little Secrets About How Weeds Move

Pamela Smith
By  Pamela Smith , Crops Technology Editor
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Soil from muddy boots was put to the test to see how much weed seed they harbored. (Photo courtesy of Joe Ikley, North Dakota State University)

When Palmer amaranth first fought back against glyphosate in the South a few years back, a bunch of midwestern farmers traveled that direction to see if the horror stories were real. Many shoes were left behind after that visit.

Joe Ikley recently proved why ditching that footwear was a smart move when he scraped the dirt off some muddy work boots and waited to see what would grow. Palmer amaranth (pigweed), grasses and hairy nightshade all emerged.

"We'd been flagging off a new research site in muddy conditions," said Ikley, a North Dakota State University weed scientist. "We planted the mud from two pairs of boots in a greenhouse flat.

"It really wasn't all that much mud. What it shows though is that it doesn't take much to move weed seed," Ikley said.

Confinement livestock producers long ago took a hard look at biosecurity measures to protect against disease. Showering and wearing disposable boots and overalls were common requirements if you wanted to get inside a hog building. As my father used to delight in telling less-informed visitors: "Those boots aren't to keep you clean, they are to protect my pigs."

In another incident on the home farm, we noticed a new, gnarly weed that tried to gain a foothold in our pasture after buying some sheep from Oklahoma. Several years ago, I took a load a compost from a local cattleman and inherited a super aggressive spiny amaranth issue.

I can also attest that my Golden Retrievers are as accomplished at snagging weed seeds as they are tennis balls.

None of this surprises Ikley. His idea to plant his muddy boot discard was to make a point to his own field staff about the need for more biosecurity. "We often talk about being careful about moving equipment, especially combines since they bring in a lot of seed that gets trapped in a lot of areas," Ikley said.

Weed scientists often suggest harvesting your cleanest fields first and to save those where herbicide resistance is a known fact to the end. Find proper cleanout procedures between fields and instructions for deeper clean outs here:…

"But, I think we need to start talking more about planters and cultivation equipment. Our little experiment highlights that anything that moves any soil will also move some weed seeds -- and that includes our own boots," he added.

That has implications for crop scouts, weed hoeing crews and even, curious ag journalists. Where your boots leave footprints, they could also spread weed seeds.

Listen in as Ikley and University of Missouri's Mandy Bish talk about the War Against Weeds in a podcast:…

Pamela Smith can be reached at

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