Weeds are rapidly becoming immune to every herbicide available in the market today and weedkiller manufacturers are struggling to keep up.
Last year, Dallas Peterson, a scientist from Kansas State, found Palmer amaranth or better known as pigweeds, growing in a field where he was conducting his research. He reported that the weeds survived chemical sprays he has used to get rid of the pests.
"We were just not able to control or kill those weeds following those herbicide applications," he told NPR.
To study the weeds, he and colleague Mithila Jugulam, who studies herbicide resistance, dug out the plants and brought them to the lab. They grew 10 pigweeds until they produced seeds and replanted those seeds to be observed.
They confirmed that pigweeds are immune to 2,4-D. Some of the plants can also survive dicamba, although this is not scientifically confirmed yet.
Pigweeds have been a growing problem since 2015 when scientists first discovered that the weeds could not be killed by glyphosate, which is the primary ingredient of popular herbicide Roundup. The herbicide-resistant weeds have already spread in farmlands in the South and increasingly in the Midwest.
Stanley Culpepper, a scientist from the University of Georgia and one of the researchers who discovered the herbicide-resistant pigweeds, said that he is not surprised that the pests are outsmarting farmers and biotech companies.
"I'm telling you, as a weed scientist, it's just an absolutely fascinating plant," he stated. "You have to respect it, and the first thing to respect it is, [know that] this plant will outsmart me if I do the same thing over and over again."
He also noted that no new herbicide has been introduced in the market since 1984.
How To Prevent Pigweeds From Taking Over
Culpepper said that there are still ways to control pigweed infestation. The key is to use several different tools. They recommend using multiple chemical sprays, planting more cover crops, and alternating crops.
Larry Steckel, a weed specialist from the University of Tenessee, stated via a report by Successful Farming last December that planting cover crops, in particular, seems to be working for soybeans.
Farmers are hoping that manufacturers are using the recent studies performed on pigweeds and other herbicide-resistant weeds to create new products that can prevent the pests from taking over farmlands.