Urgent Need for New Weed Control

Thursday, March 19, 2026

Little change from worst weeds identified in 2022

Based on a report from the Weed Science Society of America

Results from the 2025 Weed Science Society of America (WSSA) broadleaf crops weed survey highlight the need for new herbicides and alternative weed management strategies. Those needs were revealed by comparing WSSA’s 2025 survey results with those obtained in 2022.

“Producers have continued to rely on the same herbicide chemistries for years to control problematic weeds,” says Matthew ‘Cole’ Woolard, PhD, WSSA Science Policy Fellow and Texas Tech University graduate assistant, who helped compile the survey results, along with Aleah-Butler Jones, WSSA Science Policy Fellow, a fourth-year PhD candidate in horticultural biology at Cornell University. “Numerous weeds, such as Palmer amaranth, waterhemp, and kochia, have evolved resistance to herbicides that crop producers continue to rely on for weed control.”

WSSA’s Executive Director of Science Policy, Lee Van Wychen, coordinates WSSA’s weed survey every year. He distributed the 2025 online survey to all the members of the WSSA and its member affiliates in Canada and the U.S., collecting responses during July and August 2025. Member affiliates include those from the Canadian Weed Science Society (CWSS), Aquatic Plant Management Society (APMS), North Central Weed Science Society (NCWSS), Northeastern Weed Science Society (NEWSS), Southern Weed Science Society (SWSS), and Western Society of Weed Science (WSWS).

“The 2025 survey results mirror the 2022 survey, indicating that we have not yet found any new weed management strategies that are effective on our most problematic and common weeds,” concludes Woolard. “These latest results are important for our researchers and farmers, because our key broadleaf crop weeds — pigweed species, common lambsquarters, kochia — remain problematic in fields.”

In WSSA’s 2025 survey, 347 members in seven Canadian provinces and 42 of the 50 U.S. states provided input. “This year’s responses also highlight our need for alternative herbicide chemistry or management strategies for the weeds that continue to be problematic annually,” emphasizes Woolard.

“The weeds that continue to be the most common and most troublesome have evolved resistance or have limited control options. Therefore, we need to continue looking for alternative weed management strategies to fortify our conventional practices to control weeds.”

Researchers across North America are evaluating new technologies such as weed zappers, harvest weed-seed management products, weed flamers, and cover crops, among others, as tools that could be integrated into season-long weed management systems, notes Woolard. If these options prove viable, it will give producers additional tools to the current chemical options for weed control, he says.

The main results from the 2025 survey are as follows:

• The most common weeds among the 13 crops evaluated remain almost identical to those in the 2022 survey. The ranking of the weeds may have shifted slightly; however, nine of the top 10 remained the same: common lambsquarters, Palmer amaranth, kochia, waterhemp, redroot pigweed, nutsedge species, morningglory species, horseweed (marestail), and common ragweed.
• A similar trend was observed for the most troublesome weeds. Of the weeds listed, eight out of 10 were identical between the 2022 and 2025 surveys. They are Palmer amaranth, kochia, common lambsquarters, nutsedge species, waterhemp, horseweed (marestail), common ragweed, and morningglory species.
• For soybeans, waterhemp surpassed Palmer amaranth as the most problematic weed.
• Hemp was added to the 2025 survey for the first time, providing a total of 13 crops compared to 12 in the 2022 survey. Pigweed species also ranked among the most common and troublesome weeds for this crop.

Finally, a surprising number of volunteer crops were identified as common and troublesome weeds in this survey.

While the frequency was not high enough to rank among the top five most common and troublesome weeds for any crop, this is a trend worth monitoring to see whether volunteer crop management becomes a more challenging weed problem in the future. BF