On October 13, 2017, the U.S. Environmental Protection Agency (EPA) announced that it had reached an agreement with Monsanto, BASF, and DuPont on measures “to further minimize the potential for drift to damage neighboring crops from the use of dicamba formulations used to control weeds in genetically modified cotton and soybeans,” and “new requirements for the use of dicamba ‘over the top’ (application to growing plants) will allow farmers to make informed choices for seed purchases for the 2018 growing season.”

EPA states that in a series of discussions, it “worked cooperatively with states, land-grant universities, and the pesticide manufacturers to examine the underlying causes of recent crop damage in the farm belt and southeast,” “sought extensive input from States and [U.S. Department of Agriculture (USDA)] cooperative extension agents from across the country, as well as the pesticide manufacturers, on the underlying causes of damage,” and “reviewed all available information carefully and developed tangible regulatory changes for the 2018 growing season.”

The label changes that certain registrants of dicamba products have agreed to impose additional requirements for "over the top" use of these products next year.  These new requirements include:

• Classifying products as "restricted use," permitting only certified applicators with special training, and those under their supervision, to apply them; dicamba-specific training for all certified applicators to reinforce proper use;

• Requiring farmers to maintain specific records regarding the use of these products to improve compliance with label restrictions;

• Limiting applications to when maximum wind speeds are below 10 mph (from 15 mph) to reduce potential spray drift;

• Reducing the times during the day when applications can occur;

• Including tank clean-out language to prevent cross contamination; and

• Enhancing susceptible crop language and recordkeeping with sensitive crop registries to increase awareness of risk to especially sensitive crops nearby. 

This announcement follows two compliance advisories issued by EPA in August 2016 and July 2017 on what EPA described as the high number of complaints received regarding crop damage from the alleged misuse of herbicides containing the active ingredient dicamaba.  EPA’s August 2016 compliance advisory stated that the Missouri Department of Agriculture received 117 complaints alleging misuse of pesticide products containing dicamba, and Missouri growers estimated that more than 42,000 acres of crops had been adversely affected.  Further, that similar complaints alleging misuse of dicamba products were received by Alabama, Arkansas, Illinois, Kentucky, Minnesota, Mississippi, North Carolina, Tennessee and Texas.  In the spring of 2016, EPA issued a proposal to register dicamba to control weeds in cotton and soybean that have been genetically engineered to tolerate dicamba.  In November 2016, EPA issued a conditional registration for dicamba on dicamba-tolerant cotton and soybean to Monsanto for its Xtendimax product; and EPA recently approved a label amendment made by Monsanto for Xtendimax which includes “additional restrictions further minimizing off-field movement of the active ingredient dicamba.”

EPA’s July 2017 compliance advisory states that by early July, EPA had received reports of hundreds of complaints to state agencies in Arkansas, Missouri, and Tennessee, a significant increase from 2016; lists the three new conditional registrations issued late last year (including Xtendimax); and states that only these new registered products may be lawfully applied over-the-top of growing soybeans and cotton.  It discusses what it describes as unlawful applications of dicamba products, and states that “[e]xcept for the new conditionally registered dicamba products, application of a dicamba product during either the cotton or soybean crop growing season is unlawful under FIFRA.”

EPA’s July 2017 compliance advisory further states that each of the conditionally approved dicamba herbicide products has labeling that provides mandatory directions for use, restrictions, and special precautions that must be followed, and that the labels of the new products require specific and rigorous drift mitigation measures to further reduce the potential for exposure from spray drift including:

• No application from aircraft;

• No application when wind speed is over 15 mph;

• Application only with approved nozzles at specified pressures; and

• Buffer zones to protect sensitive areas when the wind is blowing toward them.

Commentary

The reports of and concerns about potential damage to crops in connection with the application of dicamba illustrate a problem that has long been discussed, which is the potential for unintended impact when a pesticide that has been specifically designed for use with one or more crops that have been genetically engineered to be tolerant to the pesticide is applied in close proximity to other crops that do not share these tolerant characteristics. 

The dicamba case also illustrates the differing views on potential misuse issues.  Some observers have questioned whether all of the reported dicamba incidents were due to misuse or misapplication of the product.  Although the 2018 label changes are designed to mitigate the potential for damage to sensitive crops, some question whether some unanticipated or as yet not completely understood factor may be at play in some of the incident reports.  One issue raised by some researchers concerns potential unexpected volatility of the product even when applied according to the label directions by well-trained applicators.  The registrants have disputed this suggestion, but it is an area which will likely be more thoroughly researched over the next few growing seasons.

More information on EPA’s regulatory action on dicamba is available on EPA’s website.