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Dicamba: Training for success

Article cover photo
A soybean plant grows in a greenhouse at Monsanto’s research facility in St. Louis. Company officials hope that training sessions will increase on-target applications of dicamba this year. (Photo: Joseph L. Murphy/Iowa Soybean Association)

By Matthew Wilde, ISA senior writer

Monsanto officials hope a winter of intensive training sessions and last years’ experience will increase effectiveness of dicamba herbicide in soybean fields this year.

The global agriculture company hosted Iowa Soybean Association (ISA) staff at its research facilities in St. Louis on May 7. Monsanto showed off its seed chipping and genetic sequencing laboratories, technological innovations, growth chambers and greenhouses, among other things. All geared to provide farmers with the tools, seeds, and software to cultivate feed, food and clothing fiber while preserving the environment.

Dicamba testing is ongoing to improve formulations and application success. Monsanto’s Mindy Whittle, soybean industry affairs lead, and Tom Eickhoff, agronomic systems lead, provided an update on the future of the herbicide and related technology.

Farmers nationwide reported excellent weed control in 2017 using new low-volatile formulations of dicamba made by Monsanto and other companies. But damage to nontolerant crops occurred. Drift, volatility and applicators not following label instructions were the primary culprits, industry and government officials.

While drift and volatility are risks subject to further investigation, ongoing training for strict adherence to label instructions continues to be Monsanto’s primary focus for successful integration of dicamba-tolerant crops and the herbicide chemistry system in 2018 and beyond.

“I think what Monsanto and other registrants have done is give applicators every possible tool to make a successful application,” Whittle said. “Our goal was to hone down and clarify elements of the label that are critical based on our learnings from last year and changes made by the EPA (Environmental Protection Agency).”

The EPA reached an agreement in October with technology providers to reclassify new formulations of dicamba as “restricted use.” Only certified applicators with special training, and those under their supervision, can apply Monsanto’s XtendiMax™ with VaporGrip® Technology, BASF’s Engenia® and DuPont’s FeXapan™ with VaporGrip Technology this year.

More than 80,000 applicators/farmers attended dicamba training courses sponsored by the companies leading up to the 2018 crop year. In Iowa, more than 5,000 were certified to use the products. Companies collaborated with states and universities to educate and certify users.

Classroom-style courses have concluded, but online training is available through company websites.

Tom Eickhoff, Monsanto agronomic systems lead, briefs Iowa Soybean Association staff members about dicamba use. More than 80,000 people attended dicamba training courses within the past year. (Photo: Joseph L. Murphy/ Iowa Soybean Association)

On-target goal

The goal is to curb dicamba damage and off-target movement. More than 2,700 dicamba-injury investigations were conducted nationwide — 110 in Iowa — in 2017, according to data compiled by the University of Missouri and the Iowa Department of Agriculture and Land Stewardship.

“I think all of the training and everything we’ve done sets us up for a really positive experience this season,” Eickhoff said.

“We’re happy with the numbers and partnerships,” added Whittle.

Training sessions focused on areas of needed improvement based on customer feedback, Eickhoff said. Several examples include:

  • Using approved nozzles (Monsanto distributed more than 1 million label compliant nozzles).
  • Adhering to appropriate buffer zone requirements to protect sensitive areas (110-220 feet, depending on herbicide rate).
  • Do not apply when wind is blowing toward adjacent susceptible crops.
  • Spraying only when the wind speed is between 3-10 mph.
  • Only using approved tank mixes.
  • Following proper tank cleanout procedures.

“These are areas we could do a better job,” Eickhoff said.

A complete list of application requirements can be found at

The future

Conditional two-year registrations for XtendiMax with VaporGrip Technology, Engenia and FeXapan with VaporGrip Technology are set to expire at the end of the year. The EPA is expected to decide in September or October whether to allow over-the-top use of dicamba beyond the 2018 growing season, Eickhoff said.

He is not certain what metrics the EPA will use to make that decision.

“What does success look like in 2018? To me, the No. 1 thing is dicamba is doing a great job controlling weeds,” Eickhoff said. “Farmers need tools (like this).”

Monsanto projects about 40 million acres of Roundup Ready 2® Xtend soybeans, genetically engineered to tolerate dicamba and glyphosate, will be planted this year. Nearly half of the nation’s crop.

Even though dicamba was reformulated to reduce off-target movement due to volatility (herbicide turns from liquid to gas), it didn’t stop it. Damage to nontolerant crops occurred even though many applicators followed label instructions, farmers reported.

Monsanto developed an app that helps dicamba users plan their applications by predicting weather conditions and temperature inversion risk for their fields.

A temperature inversion is a weather phenomenon in which the air at the earth’s surface is cooler than the air above it. It usually happens at night or on cloudy days and when winds are calm. Inversion increases the risk that dicamba can drift onto nearby fields and damage other crops because tiny herbicide droplets remain suspended in the air during an inversion.

Inversion drift occurs when herbicide spray particles never hit the plant, remain suspended in the air and then move to off-target plants. Herbicide volatilization generally occurs after spray has settled onto target plants and then later volatilize and move to off-target plants in a gas form, but still in concentrations that can cause injury.

The RRXtend Spray App provides location-specific weather forecasts, digital record keeping capabilities and educational resources related to the Roundup Ready® Xtend Crop System. Growers can download the app for free on the Apple App Store® and on Google Play®. It’s been downloaded about 11,000 times as of May 6, company officials said.

“We learned that inversions are one of the key challenges and not one of those things we were good at understanding before,” Eickhoff said. “The app is a really nice tool people can use.”

Ed Anderson, Ph.D., ISA senior research director, said additional predictive models and risk management tools will aid applicators.

“If you can provide farmers with decisions tools, they will be more successful,” he said.

Applicators can call 1-844-RRXTEND with questions about the label and proper application techniques.

Contact Matthew Wilde at

For media inquiries, permission to republish articles or to request high-res photos, please contact Katie James, ISA Public Relations Manager at © 2020 Iowa Soybean Association. All rights reserved.

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