Tank

Staff Writer

When more and more herbicide resistant weeds started popping up, it was clear farmers could no longer rely on the same chemicals year after year.

Industry campaigns and herbicide applicators began touting the benefits of rotating herbicides annually to avoid developing resistance, and rotation quickly became common practice.

But in 2015, a team of weed scientists from the University of Illinois and the U.S Department of Agriculture-Agricultural Research Service studied the effects of herbicide rotation and found the practice actually increased resistance to glyphosate in waterhemp, a common and destructive Corn Belt weed.

What worked, instead, was mixing multiple herbicides in the same tank and spraying simultaneously. A large experiment, including 105 grain fields across Illinois, showed tank-mixing was 83 times less likely to lead to glyphosate resistance.

The study had a powerful impact with recommendations changing nearly overnight. But one of the study's authors now is urging farmers and industry players to remember tank-mixing only delays the evolution of resistance.

"I worry this practice has become overused. It's too simplistic to think all you need to solve the challenges of resistance is to go on using herbicides but in a slightly different way," said Aaron Hager, weed scientist and faculty Extension specialist in the Department of Crop Sciences.

Waterhemp now is resistant to herbicides from at least seven modes of action, despite the advantages of tank-mixtures, Hager said. And some waterhemp populations are resistant to herbicides to which they have never been exposed.

Hager emphasizes that the problem of resistance to herbicides is the direct result of over-reliance on a single simple solution: chemical weed control.

The problem, in his view, won't be solved by exclusively using the same tools, but in different ways. Instead, he said farmers should diversify tactics and focus on preventing or eliminating weed and seed production.

"Herbicides will continue to be valuable tools to help prevent crop yield loss, but we also must consider additional tactics to ensure no waterhemp plant is allowed to produce seed during the growing season. All we know with certainty is that if plants can't produce seed, the frequency of any resistance mechanism can't change or grow. Even a few seed-bearing waterhemp plants remaining in the field at harvest could contain the newest herbicide-resistance mechanism," Hager said. "It's worth repeating: consider additional tactics to ensure no weed seed production."

The House Committee on Agriculture wants input on the next farm bill.

An online portal, available at agriculture.house.gov by clicking on "2023 Farm Bill" under "policy," solicits public feedback on the bill through June 9.

Committee leaders believe this tool will allow members to better share the experiences and priorities of agricultural producers and consumers.

In addition to questions regarding location and occupation, the online portal asks responders to specify the farm bill title they are most interested in as well as which programs they believe are performing well. It also asks for feedback regarding programs that could be improved and additional ideas that should be considered. There is space for respondents to include additional information.

Congress last approved a new farm bill in 2018. It will expire on Sept. 30, putting increasing pressure on legislators to get a new bill passed.

The massive piece of legislation is divided into 12 sections, or titles, that drive agriculture programs and funding in a number of areas. They include commodity programs, conservation, trade, nutrition, credit and rural development.

Staff Writer

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