Herbicide-Resistant Weeds: Understanding the Challenge and a Path Forward

Aug 11, 2025

By Vipin Kumar and Mandeep Singh et.al

Herbicide-resistant weeds are a growing threat to the sustainability and profitability of agronomic cropping systems in Nebraska, from corn and soybean production fields in eastern Nebraska to sugarbeet in Nebraska Panhandle. With increased herbicide use — particularly in simplified weed control programs — more weed species are evolving resistance to herbicides, creating challenges for farmers.

Herbicide-Resistant Weeds in Nebraska and in the Midwest

In Nebraska and across the Midwest, herbicide-resistant Palmer amaranth, waterhemp, kochia, common ragweed and marestail are common. Many of these species are resistant to widely used herbicides, including atrazine (Group 5), glyphosate (Group 9), protoporphyrinogen oxidase (PPO)-inhibitors (Group 14), and acetolactate synthase (ALS)-inhibitors (Group 2). In fact, nine weed species in Nebraska have confirmed resistance to one or more herbicides: common ragweed, giant ragweed, Johnsongrass, kochia, marestail, Palmer amaranth, redroot pigweed, shattercane, and waterhemp (Jhala 2017). Some populations, particularly Palmer amaranth and waterhemp are resistant to five or more herbicides with varying mode of action (MOA), including groups 2, 5, 6, 9, 14 and 27. This significantly reduces post-emergence herbicide options and forces farmers to rely on alternate herbicide programs.

The evolution of resistance is accelerated by repeated use of the same herbicide(s) with the same mode of action, especially when they are used without incorporating cultural or mechanical weed control tactics. The overuse of glyphosate in glyphosate-resistant crops has been a major driver of the evolution of glyphosate-resistant weeds. For example, six glyphosate-resistant weeds — including common ragweed, giant ragweed, kochia, marestail, Palmer amaranth and waterhemp — have been confirmed in Nebraska (Jhala 2017).

The evolution of multiple herbicide-resistant weeds has become one of the most pressing concerns. Certain weeds survive herbicides belonging to two or more MOAs, making chemical control alone ineffective in many cases.

Source : unl.edu

Video: Why Invest in Canada’s Seed Future? | On The Brink: Episode 3

Darcy Unger just invested millions to build a brand-new seed plant on his farm in Stonewall, Manitoba so when it’s time for his sons to take over, they have the tools they need to succeed.

Right now, 95% of the genetics they’ll be growing come from Canadian plant breeders.

That number matters.

When fusarium hit Western Canada in the late 90s, it was Canadian breeders who responded, because they understood Canadian conditions. That ability to react quickly to what’s happening on Canadian farms is exactly what’s at risk when breeding programs lose funding.

For farmers like Darcy, who have made generational investments based on the assumption that better genetics will keep coming, the stakes are direct and personal.

We’re on the brink of decisions that will shape our agricultural future for not only our generation, but also the ones to come.

What direction will we choose?

On The Brink is a year-long video series traveling across Canada to meet the researchers, breeders, farmers, seed companies, and policymakers shaping the future of Canadian plant breeding. Each week, a new story. Each story, a piece of the bigger picture.

Episode 3 is above. Follow Seed World Canada to catch every episode, and tell us: Do you think the next generation will have the tools they need to success when they takeover? How is the future going to look?