10,000-farmer sample seeks best management plan answers to resistance
When a farmer peers over the wall and sees weed barbarians at the gate, it’s likely they’re already racing through the city. Weed resistance varies according to region, state, farm and field. However, the great constant is plain: Herbicide-resistant weeds are getting worse everywhere. In response, an unprecedented resistant-weed survey is hitting mailboxes at 10,000 farms coast to coast. The USDA-funded project is focused on corn, cotton, soybeans and sugar beets.
Mike Owen is leading an interdisciplinary team of weed scientists, economists and sociologists to uncover farmers’ biggest weed concerns and determine the extent of regional and crop differences. The survey aims to identify barriers to adoption of best management practices (BMPs) to mitigate herbicide resistance and encourage on-farm implementation. Essentially, Owen, a weed specialist with Iowa State University, hopes the survey data will help facilitate a change in resistant-weed management strategies.
In some geographies, agriculture is rapidly approaching a day without herbicide options for particular weeds. Many Midsouth farms are infested with Palmer amaranth resistant to ALS (Group 2) herbicides, PPO (Group 14) herbicides and glyphosate (Group 9). Drive north into Iowa and the situation is better but only for the moment. Approximately 70% to 80% of fields in Iowa are predicted to have weed resistance to ALS inhibitors, he adds.
“A majority of fields in the Midwest don’t have proverbial train-wreck fields picked up on by the popular press,” Owen describes. “In many instances, if weed levels don’t interfere with harvest, a producer doesn’t worry. Old models suggest about 30% of a weed population has to demonstrate resistance before a grower becomes aware of herbicide resistance in a given field. That’s when a grower sits up and wonders what to do.”
The survey combines social science with physical science to take in multiple views of weed resistance. “Weed problems steal yield and real money from fields and the theft is quickly getting worse,” Owen says. He urges farmers to return completed surveys, which are arriving in mailbox and email form. The survey sample covers farms of all sizes. “We absolutely need information from everyone, regardless of acreage,” he adds.
Part of the multi-disciplinary team, Jason Norsworthy, University of Arkansas weed scientist, notes weed-resistance awareness is changing across agriculture as the efficacy of the herbicide arsenal weakens. He says several groups and agencies are discussing whether resistance management should be incentivized or mandated. “Personally, I prefer incentives over mandates; definitely the carrot over the stick,” he says.
Echoing Owen, Norsworthy says getting back survey information is vital. He cites LibertyLink crops as a harbinger example. Liberty (glufosinate) is the only postemergence option for controlling pigweed on some farms—period.
Weed technology is a phenomenal benefit to mankind. Yet, the golden age of herbicides has ended and given way to unprecedented weed resistance and an entirely new farming dynamic.
“We have to come up with other ideas. We have to change opinions of how farmers operate,” Owen says. “You’ve got 5,000 acres in the Midwest and want to treat them all the same? No. Weed strategies must be different on every single field.”
The survey consists of 16 questions and should take 20 minutes to complete. “If a grower gets this in the mail and sighs, he’ll be rethinking his reaction if agriculture continues to lose the efficacy of herbicide chemistries,” Owen says.