Battling weeds is nothing new for Illinois farmers, but evolving species like waterhemp that are taking root in fields bring a new challenge.  

As Suzanne Bissonnette, assistant dean of agriculture and natural resources at the University of Illinois Extension, points out, history shows that the weeds farmers now face are not the same as previous weeds because of farming practices.

“When we used to have conventional tillage when farmers actually plowed fields ... that actually surprisingly changed the weed species ... out in the field,” Bissonnette said.

In the days of tilling the ground, a weed called yellow rocket was vast and covered fields in a yellow blanket. Once farming practices moved away from tilling, the yellow rocket became less prevalent.  

One weed that current farmers in Illinois are all too familiar with is waterhemp, which wasn't widespread until approximately 25 years ago. Aaron Hager, weed scientist and associate professor at the University of Illinois, says now nearly every crop farmer in the state is battling it.

“To watch this species go from a species of almost obscurity to now being our number one driver species, or the species about which farmers are making a lot of their weed management decision ... has been absolutely amazing to see,” Hager said.

Weeds are a moving target for today's farmers, as invasive species adapt to their environment. Hager likens invasive species to bacterial infections in humans that have become resistant to antibiotics.

“One of the biggest issues that farmers are facing now in Illinois ... are simply species that have evolved resistance to various herbicides,” Hager said. “We can no longer effectively control them with some of the the products that we have had much success with for many years.”

Farmers have advanced their weed management tactics with new herbicides and different farming practices to protect their crop yield. One practice farmers often deploy against weeds is reducing the space between rows to limit the sunlight weeds get and stunt their growth.  

“When dealing with resistant weeds, the best place to be is in front of this – stay in front, do whatever you can to make sure these population numbers don't build up in your field,” Hager said.

As Illinois farmers battle weeds like waterhemp, future generations will likely face new invasive species. According to Hager, the key to preparing for the future of weeds is continually researching as well as adapting practices as needed to keep Illinois’ fields producing healthy crops.

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