The State of Dicamba Regulation
Sophie Watterson, River Protection Intern

“Significant cupping of leaves from dicamba drift on non-Xtend soybeans planted next to Xtend beans in research plots at the Ashland Bottoms farm near Manhattan. – Dallas Peterson, K-State Research and Extension.” Source: K-State Research and Extension Flicker Account

At the federal level, the EPA is responsible for registering agricultural chemicals like dicamba under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Dicamba registration expires every two years to “ensure that the EPA retains the ability to easily modify the registration or allow the registration to terminate if necessary” (US EPA). In 2018, the EPA decided to extend the three existing registrations of dicamba to Bayer (Monsanto), Corteva, and BASF. Dicamba is registered for use on dicamba-tolerant cotton and soybean in the following 34 states: Alabama, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Illinois, Iowa, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wisconsin (US EPA).

In 2017, there were over 2,700 official cases of crop damage reported due to dicamba, according to a study by Dr. Kevin Bradley at the University of Missouri. In response, the EPA made certain changes to the pesticide label when it extended dicamba registration in 2018 “to further minimize the potential for off-target movement” (US EPA). These changes include:



  1. Over-the-top (OTT) applications of dicamba to cotton and soybeans must be done by a certified applicator. Note: The EPA first registered dicamba for applications post-emergent over-the-top OTT for soybean and cotton in 2016. Previously, dicamba application was limited to pre-plant and pre-harvest cotton and soybeans.
  2. Limit OTT applications of dicamba to cotton and soybeans to only two times per field per year. The previous maximum was four OTT applications for cotton and two for soybeans per field per year.
  3. OTT spraying of dicamba is prohibited 60 or more days after planting cotton and 45 or more days after planting soybeans. Late in the growing season, other methods of weed control are recommended over dicamba spraying because leaf cover prevents dicamba from reaching the soil and, since it is highly volatile, also increases the chance that dicamba will move off-site.
  4. OTT applications of dicamba must not begin for at least one hour after sunrise and must cease two hours before sunset. These are times of day when temperature inversions are most likely and facilitate the suspension and movement of dicamba particles in the air.
  5. Specific equipment clean-out instructions. To prevent unintentional transfer of dicamba to intolerant crops via shared equipment.
  6. An omnidirectional infield buffer of 110 feet downwind and 57 feet in the other directions to protect endangered species. The downwind buffer was pre-existing but the 57-foot omnidirectional buffer is a new requirement.
  7. Label changes for clarity, including a statement that dicamba is more volatile in acidic environments (US EPA).


Despite these EPA regulatory changes from 2018, crop damage complaints related to dicamba persist. In 2018, the “Association of American Pesticide Control Officials (AAPCO) reported that approximately 1,400 official complaints of alleged dicamba injury [damage due to off-site movement of dicamba] were reported to the state regulatory authorities” (US EPA). Only 16 of 34 registered states report regularly to AAPCO so it is likely that this number underestimates dicamba-related crop damage. A few states have taken action to further limit or regulate dicamba. In July of 2017, Missouri placed a ban on the sale and usage of dicamba until additional labeling was introduced and Arkansas banned the sale of dicamba for a 120-day period (Britt E. Erickson, Chemical & Engineering News). As of July 2019, Illinois and Arkansas have set the most limitations on the use of dicamba. The Illinois Farm Bureau placed the following restrictions on dicamba for 2019, in addition to the federal labeling requirements from 2018:

      • The implementation of a cutoff date of June 30, 2019, for application to DT (dicamba-tolerant) soybeans.
      • Prohibiting application when the wind is blowing toward adjacent residential areas.
      • Required consultation of the FieldWatch sensitive crop registry before application, as well as compliance with all associated record keeping label requirements.
      • Maintaining the label-specified downwind buffer between the last treated row and the nearest downfield edge of any Illinois Nature Preserves Commission site.
      • Recommendation to apply product when the wind is blowing away from sensitive areas, which include but are not limited to bodies of water and non-residential, uncultivated areas that may harbor sensitive plant species (Illinois Farm Bureau).


In 2019, the Arkansas Department of Agriculture decided on a May 25 cutoff date for the application of dicamba to cotton and soybeans, although 2018’s cutoff date was April 16. The Arkansas Department of Agriculture also set a half-mile buffer to be maintained around fields of sensitive row-crop fields and a one-mile buffer to be maintained around specialty crops, organic crops and research fields. Applicators in Arkansas are not allowed to mix dicamba with glyphosate, since this has been shown to increase the volatility of dicamba (Pamela Smith and Emily Unglesbee, DTN Progressive Farmer).

The Minnesota, North Dakota, and South Dakota Departments of Agriculture also set cutoff dates for dicamba application in 2019: June 20 in Minnesota and June 30 in the Dakotas. Pesticide regulators in Indiana planned to submit a 24(c) label with downwind buffer requirements, “However, after state pesticide regulators met with several agriculture industry groups, including the Indiana Farm Bureau, the Agribusiness Council of Indiana and the Indiana Soybean Alliance, the 24(c) application was abandoned” (Pamela Smith and Emily Unglesbee, DTN Progressive Farmer). Section 24(c) of FIFRA states that “A State may provide registration for additional uses of federally registered pesticides formulated for distribution and use within the state to meet special local needs . . .”

Despite receiving hundreds of dicamba-related complaints between 2016 and 2020, other than a temporary ban issued in 2017 for the 2018 growing season, there has not been official action taken in Missouri to limit the sale/use of dicamba. As of February 2020, the Missouri Department of Agriculture had a backlog of over 600 complaints from farmers related to dicamba drift from another farm harming their crops. St. Louis Public Radio reported that “Since 2016, the department has received 755 dicamba-related complaints. The complaints peaked at 315 in 2017, then fell to 220 in 2018 and 98 in 2019.”

Bayer-Monsanto is one of three companies that are registered with the EPA to use dicamba, a toxic agricultural chemical like glyphosate. Dicamba was developed as an herbicide for genetically-modified varieties of soybeans and cotton which are resistant to the chemical. This has caused a lot of conflict in agricultural communities since Bayer-Monsanto released new dicamba-resistant seeds in 2016, because dicamba not only kills weeds, but any crop varieties which have not been engineered for resistance.

In the fall of 2016, a Missouri farmer allegedly shot and killed his neighbor, Mike Wallace, when the men met up to address Wallace’s concerns about dicamba drifting onto his property. Dicamba is highly volatile and soluble, which means it travels easily through air and groundwater, and often drifts into nearby fields where crops are not resistant. When dicamba registration was extended in 2018, the EPA made certain changes to the pesticide label “to further minimize the potential for off-target movement”. However, in 2018 there were still thousands of complaints reported to the Association of American Pesticide Control Officials (AAPCO) about crop damage from dicamba drift. As of February 2020, multiple states have had trouble keeping up with the complaints and have asked EPA for assistance. In January 2020, peach farmer Bill Bader in Dunklin County, Missouri, sued Bayer-Monsanto for irreparable damage to his 1,000 acre peach farm due to dicamba-drift. By February 2020, “a jury in U.S. District Court in Cape Girardeau [awarded Bader] $15 million in actual and $250 million in punitive damages.”

Concerns about dicamba exposure reflect a larger conflict in the agricultural community between independent farmers and agribusiness. Small farmers can’t protect their crops against dicamba drift, while agricultural companies like Bayer-Monsanto continue to apply these herbicides because they help increase production for resistant crop varieties. Small farmers may resort to buying expensive, genetically-modified seeds from these companies so their crops won’t fail because of chemical exposure. In turn, we lose seed variety and put more money in the pockets of corporations.

Fortunately, on June 4, 2020, the U.S. Court of Appeals for the Ninth Circuit overturned the EPA’s approval of the use of dicamba. The court said “the EPA failed to comply with a federal pesticide law requiring it to consider the risks of the chemical when it granted a two-year conditional approval in late 2018” (KPIX San Francisco Bay Area, Channel 5). On June 9, 2020, the EPA issued its Cancellation Order pertaining to the registration of the three pesticide products containing dicamba that were on the market prior to the court’s order. According to the Cancellation Order, those who were in legal possession of these pesticides before the court ruling are allowed to continue to use the pesticides as directed, with a cut-off date of July 30, 2020.

While legal challenges and regulatory oversight continue to be needed to support the growing of safe, healthy food by small-scale farmers, you can make sure you are supporting an environmentally-responsible, local food system by supporting small-scale farmers in MCE’s Known & Grown STL program. Learn more about the program at