Iowa farmers try to head off "super weeds" - KWWL - Eastern Iowa Breaking News, Weather, Closings

Iowa farmers try to head off "super weeds"

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JOHNSON COUNTY (KWWL) - Decades ago, the agricultural company Monsanto invented a weed killer that revolutionized herbicide application for farmers.

It's called Roundup, and farmers were eventually allowed to spread it over their crops, which have since been modified to tolerate the chemical.

But weeds are beginning to fight back.

Steve Swenka, who farms near North Liberty, has been hearing about weeds that stand their ground against the widely-used herbicide.

"There have been some Roundup-resistant weeds in Missouri, particularly in southern Missouri, and we keep hearing that all the time," Swenka told us.

He feels fortunate, though, because he hasn't spotted any of these so-called "super weeds" on his farmland. Even so, he's taking steps to avoid an invasion. For instance, he doesn't use Roundup on all of his crops.

"When you use it year-to-year on the same fields of both corn and beans, there is where it develops its resistance."

Iowa State University agronomist Jim Fawcett says farmers have been favoring Roundup over other herbicides because it's easy to use, and fairly cheap. But therein lies the problem: he tells us too much use has led to a buildup of natural immunity in many species of weeds.

"Roundup used to kill water hemp, but it's not killing it now. Giant ragweed and mare's tail are a couple of others," said Fawcett. He explained that there are handful of plants in just about every weed species that are naturally resistant to certain types of chemicals and weed killers, so over time, the reproduce and survive.

"Eventually, you have a whole population, a new population of weeds that the Roundup isn't effective on."

If Roundup-tolerant weeds become more common in Iowa, Swenka says he and other farmers may have to revert to using different chemicals, or even old-fashioned cultivation, which is a bit more labor-intensive.

"People kind of think it's an obsolete practice now."

But he says if it's a way to stop super weeds from sprouting here, a little extra work is worth the trouble.

Online Reporter - Brady Smith

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