Memorandum Supporting Decision to
Approve Registration for the Uses of
Dicamba on Dicamba Tolerant Cotton and
Soybean

Digitally signed by
MARIETTA
MARIETTA ECHEVERRIA
Date: 2020.10.27 11:38:52
ECHEVERRIA
-04'00'
Approved by: _________________________

Marietta Echeverria, Acting Director
Registration Division
Office of Pesticide Programs

October 27, 2020

 Table of Contents
Contents

I. Summary...................................................................................................................................... 3
II. Chemical Information ................................................................................................................ 5
III. Background ............................................................................................................................... 6
IV. 2020 Registration Actions ........................................................................................................ 9
V. Stakeholder Feedback .............................................................................................................. 10
VI. Risk Assessments.................................................................................................................... 11
A. Human Health ...................................................................................................................... 11
B. Ecological ............................................................................................................................ 11
VII. Benefits and Impacts Assessments ........................................................................................ 15
A.

Benefits of the Registration of Dicamba Use in DT Cotton and DT Soybeans ............. 15

B.

Impacts Assessment ....................................................................................................... 17

VIII. Registration Decision ........................................................................................................... 18
B.

Label Requirements........................................................................................................ 22

C.

Terms of Registration ..................................................................................................... 24

D.

Registration Expiration .................................................................................................. 26

E.

Geographic Limitation of the Registration ..................................................................... 26

IX. EPA’s Effects Determinations under the ESA ....................................................................... 26

2

 I. Summary
This memorandum presents the rationale to support the decisions of the U.S. Environmental
Protection Agency (referred hereafter as EPA or the Agency) to register 1 under section 3(c)(5) of
the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), three end use dicamba products
for use on dicamba tolerant (DT) cotton and soybeans. Bayer and BASF submitted registration
applications on July 2, 2020 for new registrations of XtendiMax and Engenia for use on DT
cotton and DT soybeans. Syngenta submitted an application for a label amendment on August 12,
2020 that proposed extending the upcoming December 20, 2020 expiration date for Tavium. 2 This
document does not approve any particular product for sale and distribution. Products are
individually approved through a separate Registration Notice that is the license that permits the
sale and distribution of the pesticide product.
EPA has evaluated extensive information and data from registrants, academics, weed scientists
and field experts, information from the open literature and even though EPA did not hold a
public comment opportunity for these registration actions, the Agency received and considered
information from other stakeholders. EPA conducted robust evaluations of the risks to human
health and the environment, including risks to non-target plants from potential spray drift and
volatile emissions, as well as the benefits and impacts to users of the products and non-users.
EPA conducted species-specific evaluations to make effect determinations for federally listed
endangered and threatened species (listed species), and where necessary consulted with the Fish
and Wildlife Service 3 under section 7(a)(2) of the Endangered Species Act (ESA). A recent
decision of 9th Circuit Court of Appeals noted certain deficiencies in EPA's 2018 registration
decision for certain dicamba products for use on DT crops. While conducting its evaluations for
this new dicamba decision, EPA considered the issues raised by the Court. As explained below,
EPA believes this decision meets the FIFRA standard for registration and is supported by
substantial evidence.
Based on these robust assessments, which took into account the control measures required by the
labeling, EPA determined that the applications meet the standard for registration under FIFRA
section 3(c)(5). The labeling requirements and restrictions associated with these registration
actions include a suite of mandatory control measures that address the potential for spray drift,
volatile emissions and runoff. These include a national application cut-off date of June 30 and
July 30 for soybeans and cotton, respectively, the mandatory use of approved volatility reduction
adjuvants 4 (VRAs), and a larger infield downwind buffer. Additionally, the registrations restrict
use to certified applicators (and not by persons under their supervision) and require dicambaspecific training on the risks associated with dicamba, required control measures, and resistance
management measures necessary to prevent unreasonable adverse effects. The registration also
includes requirements for enhanced incident and resistance reporting by the registrants to ensure
One of the products described in this rationale (EPA Registration Number 100-1623; A21472 Plus VaporGrip
Technology (Alternate Brand Name: Tavium)) is still registered, but the registration is set to expire in December
2020. In the case of that product, EPA has presented the rationale for the decision to extend the registration.
2
Since Tavium is currently registered for use on DT cotton and DT soybeans, none of these registrations are
considered to include any new uses.
3
There were no listed species within the jurisdiction of the National Marine Fisheries Service that required
consultation for this action.
4
Also called volatility reduction agents (VRA) or pH buffering adjuvants.
1

3

 EPA has appropriate information to continue monitoring these registrations. EPA is also
requiring enhanced record-keeping from applicators to ensure compliance with control measures.
EPA is requiring as a term of registration the assurances from the registrants that the VRAs/pH
Buffering Adjuvants is available in amounts necessary for use with the dicamba products for use
on DT crops.
The control measures included in these registrations are quite different from those that were
approved in the actions taken in 2018. Table 1 summarizes the major 2020 control measures
compared to those in the 2018 registrations.
Table 1. Summary of major 2020 control measures compared to 2018
Element
Spray drift

2018 Decision
110 ft downwind in-field
buffer
-Limit of two OTT
applications of dicamba per
field per year for both DT
cotton and DT soybeans
-Applications only permitted
between one hour after
sunrise and two hours before
sunset
-Use allowed until specified
crop growth stage

2020 Decision
240 ft downwind in-field
buffer
-Limit of two OTT
applications of dicamba per
field per year for both DT
cotton and DT soybeans
-Applications only permitted
between one hour after sunrise
and two hours before sunset
-Calendar cutoff dates for
applications (June 30th for
soybeans and July 30th for
cotton)

Volatility – maintaining tank
pH

Advisory language

ESA – spray drift
ESA – volatility

110 ft downwind buffer
57 ft omni-directional buffer
in areas with federally listed
species

Label clarity

Included uses for both nonDT crops beyond the cotton
and soybean DT crops

Require use of a qualified
VRA/pH buffering adjuvant in
the tank for every application
310 ft downwind buffer
57 ft omni-directional buffer
in areas with federally listed
species, in combination with
the generally applicable cutoff date and VRA/pH
buffering adjuvant in counties
with federally listed species
-Only includes pre- and
postemergent uses for cotton
and soybean DT cropsCleaner label structure and
restrictions for increased
usability
-Simplified early season
restriction (crop growth stage

Volatility – timing of
applications

4

 cut-off vs. calendar cut-off
date)
Hooded sprayer option for
partial relief of certain control
measures

Spray Tank Contamination
Expiration Date
Terms of the registrations

Training requirements

Compliance assurance

N/A

When using a qualified
hooded-sprayer the spray-drift
buffer is reduced to 110 ft and
240 ft for FIFRA and ESA,
respectively (for use in
soybeans only)
Equipment clean-out
Equipment clean-out
requirements
requirements
2 years
5 years
-Testing and approval of tank -Testing and approval of tank
mixes
mixes
-Herbicide resistance
-Revised herbicide resistance
management plan
management plan
-Enhanced reporting of
-Revised enhanced reporting
adverse effects information
of adverse effects information
-Studies to address
-Assuring availability of
uncertainties
approved VRA/pH buffering
adjuvant
-Testing alternate hooded
sprayer equipment
Training required per labeling Training required, with
addition of new requirements
to include specific information
on 2020 control measures in
training materials.
- Recordkeeping requirements - Additional recordkeeping
- Restricted use
requirements related to the
new control measures
- Restricted use

II. Chemical Information
This memorandum supports three 5 dicamba registrations for use on DT soybean and DT cotton
(EPA Registration Numbers 264-1210, 100-1623, and 7969-472), as described below.
Registrants: BASF; Bayer CropScience (formerly Monsanto Company); and Syngenta Crop
Protection
Product Numbers:

Two of the three registrants (Bayer and BASF) that owned products impacted by the 2020 vacatur have submitted
new product applications to the Agency. This memorandum addresses those two product applications, as well as the
amendment Syngenta submitted to extend the expiration date for the non-vacated product, Tavium.

5

5

 1. EPA Reg. #100-1623: A21472 Plus VaporGrip Technology (Alternate Brand Name
(ABN) Tavium Plus VaporGrip Technology) (referred hereafter as Tavium)
2. EPA Reg. #264-1210: XtendiMax with VaporGrip Technology (referred hereafter as
XtendiMax)
3. EPA Reg. #7969-472: Engenia Herbicide (referred hereafter as Engenia)
Chemical Names:
The three pesticide products covered by this memorandum contain two forms of dicamba, as seen
in Table 2 below:
Table 2. Chemical Name Identification for Dicamba
Chemical Name
Alternate Chemical
Common Name Chemical Abstract
Name
Service (CAS)
Number
Dicamba (benzoic acid,
Diglycolamine salt of Dicamba DGA
104040-79-1
3,6-dichloro-2-methoxy-, dicamba (3,6salt
aka 3,6-dichloro-o-anisic dichloro-o-anisic acid)
acid)
Dicamba: N,N-Bis-(3None
Dicamba
1286239-22-2
aminopropyl)
BAPMA salt
methylamine salt of 3,6dichloro-o-anisic acid
Mode of Action: Dicamba is in the Benzoic Acid family that is used for selective control of
emerged broadleaf weeds. Like the phenoxy herbicides, dicamba mimics auxins, a type of plant
hormone and causes abnormal cell growth by affecting cell division.
Summary of Product Information:
The information from this chemical information section is summarized in Table 2 below:
Table 3. Master Table of Dicamba Products Registered for Use on DT Cotton and DT Soybeans
EPA Reg. # Product Name
Registrant Form of Dicamba
100-1623
A21472 Plus VaporGrip
Syngenta
DGA salt
Technology (ABN Tavium)
264-1210
XtendiMax with VaporGrip
Bayer
DGA salt
Technology
7969-472
Engenia Herbicide
BASF
BAPMA salt
III. Background
In January 2015, under the Plant Protection Act, the United States Department of Agriculture
(USDA) deregulated the genetically modified DT cotton and DT soybean seeds. This seed was
sold commercially in late 2015 and 2016 prior to EPA registering a pesticide product for use on

6

 these DT crops. In late 2016, following a public comment period, 6 EPA registered three dicamba
products for use with the DT trait in soybean and cotton 7. These registrations were time-limited
with automatic expiration dates in late 2018, unless EPA granted an extension of this time
limitation.
Prior to the 2016 registration actions for dicamba, dicamba uses on soybeans and cotton were
limited to use on preplant and preharvest soybeans and on preplant and postharvest cotton. The
new uses registered in 2016 under FIFRA section 3(c)(7)(B) expanded the timing of dicamba
applications by allowing a new use for postemergence over-the-top (OTT) applications to DT
cotton and DT soybean crops. Registrations for the OTT uses were granted for the lower volatility
products when compared to other registered dicamba products for non-OTT uses. Any use of the
earlier registered products on DT cotton or DT soybean crops that are not registered specifically
for postemergent use on DT cotton or DT soybean crops is inconsistent with the pesticide’s
labeling and a violation of the FIFRA.
Reports of Incidents
In 2016, EPA began receiving reports of crop injury alleged to be caused by off-target movement
from the use of dicamba. Because the registrations for OTT use had not yet been issued, EPA
concluded these 2016 incidents were related to misuse of previously registered, more volatile
dicamba pesticide products on DT cotton and DT soybeans. In 2017, over 2,700 official cases of
crop damage were reported to state departments of agriculture, estimated to be over 3.6 million
acres of soybeans 8 (nearly 4% of a total 90.2 million acres planted in 2017 according to USDA).
There was a lack of scientific consensus regarding the exact cause of these dicamba reported
incidents. Input from state agencies, farm bureaus, associations, industry, farmers, and nongovernmental organizations indicated that causes could have included not following the label or
use of an older, more volatile formulation inconsistent with those products’ labeling and thus in
violation of FIFRA, physical drift, tank contamination, and/or volatility. In response, EPA
worked with the pesticide registrants to strengthen the pesticide label directions for use for the
2018 season to further minimize the potential for off-target movement. The restrictions for all
OTT registrations of dicamba were amended in 2017 to include labeling restrictions to minimize
the potential for off-site movement of dicamba. The original expiration set for the end of 2018
remained a term of the registrations.
Beyond the requirement of FIFRA 3(c)(4) to publish a notice of receipt for certain applications and accept
comments on the limited information in such notice, FIFRA does not require EPA to provide a public comment
opportunity for a proposed decision to register a pesticide. EPA, nevertheless, provided more robust information for
public comment on its proposed 2016 dicamba decision under its public participation policy (see:
https://www.epa.gov/pesticide-registration/public-participation-process-registration-actions). Similar to the 2018
registration actions where EPA did not provide a formal public comment period, again in 2020 EPA did not provide
a formal public comment opportunity, but the Agency did receive over 120 unsolicited comments from stakeholders.
EPA considered the content of these submissions.
7
EPA Registration Number 524-617 (M1768 Herbicide/XtendiMax With Vaporgrip Technology) was the first
registration issued in 2016 as described in Final Registration of Dicamba on Dicamba-Tolerant Cotton and Soybean
(available on regulations.gov, Docket ID: EPA-HQ-OPP-2016-0187); two additional OTT dicamba use registrations
were approved later in 2016 (EPA Registration Numbers 352-913 (DuPont Fexapan Herbicide) and 7969-345
(Engenia Herbicide)).
8
Dr. Kevin Bradley Univ. of Missouri,
IPM, https://ipm.missouri.edu/IPCM/2017/10/final_report_dicamba_injured_soybean/
6

7

 Information for the 2018 growing season provided by state agencies and others also included
reports of crop injury alleged to be related to off-site movement of dicamba. The registrants
submitted adverse effects aggregated reports to EPA as required by FIFRA section 6(a)(2). The
Association of American Pesticide Control Officials (AAPCO) reported that approximately
1,400 official complaints of alleged dicamba injury were reported to the state regulatory
authorities. Damage alleged to be related to OTT dicamba applications was reported not only for
non-tolerant soybeans but also for neighboring trees, orchards, vineyards, berries, melons,
tomatoes and other vegetable crops. As to reporting of crop injury in general, AAPCO,
university researchers, and some growers state that they believe that these types of complaints
tend to be underreported. EPA received feedback that underreporting could be associated with a
desire to maintain good relationships with neighbors; fear that a damaged crop will be considered
adulterated and cannot be sold; fear that the grower will lose their organic certification; and
grower perception that no action will be taken in response to filing a report. Conversely, there
may have been issues of overreporting. The reasons provided included: damage was caused by
use of older more volatile formulations of dicamba or other chemistries; and damage reports
given in terms of acreage that reflects the size of an entire crop field and not just the portion of
the crop field that was actually damaged.
2018 Decision, Label Amendments, Conditions of Registration, and Expiration Date:
On November 1, 2018, EPA granted Bayer’s requests to extend the expiration date for their
product registered for DT crop uses (EPA Reg. No. 524-617) for two years to December 20,
2020. On November 2 and 5, 2018, EPA granted similar extension requests for BASF (EPA Reg.
No. 7969-345) and DuPont (EPA Reg. No. 352-913), respectively. In each case EPA approved
amendments to the terms and conditions of the registration as well as adding labeling restrictions
to further reduce the potential for off-site movement of dicamba from the treated fields.
Supporting documents and registration notices can be found on regulations.gov, Docket ID:
EPA-HQ-OPP-2016-0187. This action was informed by input from state regulators, farmers,
academic researchers, pesticide manufacturers, and other stakeholders. EPA reviewed substantial
amounts of new information and concluded that the continued registration met FIFRA’s
registration standards. The Agency also determined that extending these registrations would not
affect endangered species.
The additional labeling requirements for the 2018 dicamba OTT uses included the following:
• a limit of two OTT applications of dicamba per field per year for both DT cotton and DT
soybeans
• no applications to DT crops 60 days or later after planting cotton and 45 days or later
after planting soybeans or until a specified crop growth stage
• OTT dicamba applications only permitted between one hour after sunrise and two hours
before sunset
• applications may be made only by certified applicators
• equipment clean-out requirements
• an omnidirectional application buffer to protect endangered species from off-target
movement of dicamba
EPA determined that these label changes would result in a minimal reduction of the flexibility of
growers to use dicamba as a tool for resistance management. EPA also determined that the
8

 labeling changes would further minimize the potential for off-site movement. New conditions of
registration were also associated with this two-year extension. These included enhanced
reporting and additional data requirements. This was a two-year registration set to automatically
expire on December 20, 2020, unless EPA further extended it.
2019 New OTT Dicamba Product Registration
On April 5, 2019, EPA registered a product containing a combination of dicamba and Smetolachlor for OTT use on DT cotton and DT soybeans (EPA Registration Number 100-1623,
A21472 Plus VaporGrip Technology (ABN Tavium)). This combination of active ingredients
was previously an approved tank mix, and as such, the combination of active ingredients was
already being used as a tank mix for OTT on DT cotton and DT soybeans. The registration for
this dicamba product was set to automatically expire on December 20, 2020, unless EPA
extended it.
2019 Incidents
During the 2019 use season, based on reporting to AAPCO, there was an approximate 10%
increase in number of incidents from 2018 with 1,218 reported in 2018 compared to 1,345
incidents reported to the states in 2019. According to EPA’s Incident Data System, there were
1,400 incidents reported in 2017, 2,600 reported in 2018 and nearly 3,000 reported to EPA in
2019. Although, reports have continued to increase nationally, there is variability in numbers of
reports from individual. Some states (e.g., Kentucky, Missouri, Minnesota, Ohio) have seen a
decrease.
2020 Court Order
On June 3, 2020, the Ninth Circuit Court of Appeals issued a decision in National Family Farm
Coalition, et. al., v. EPA, 960 F.3d 1120 (aka Dicamba II), ordering the immediately effective
vacatur of three pesticide registrations containing the active ingredient dicamba for use on DT
crops (XtendiMax with Vaporgrip Technology (EPA Reg. No. 524-617); Engenia (EPA Reg.
No. 7969-345); and FeXapan (EPA Reg. No. 352-913)). The Court found that EPA’s decision to
approve these dicamba products was not based on substantial evidence in that “EPA substantially
understated risks that it acknowledged and failed entirely to acknowledge other risks.” The
product containing dicamba plus s-metolachlor (Tavium) was not vacated, so it remained
registered with the expiration date of December 20, 2020.
On June 8, 2020, EPA issued a cancellation order providing growers, commercial applicators and
distributors with direction on how to effectuate the vacatur. This cancellation order outlined the
limited and specific circumstances under which existing stocks of the three affected dicamba
products could be used for a limited period of time. Growers and commercial applicators were
allowed to use existing stocks that were in their possession as of June 3, 2020, as long as the use
was consistent with the product’s previously approved label, but only until July 31, 2020.
IV. 2020 Registration Actions
Bayer and BASF submitted registration applications on July 2, 2020 for new product
registrations (XtendiMax and Engenia) for use on DT cotton and DT soybeans. Syngenta
submitted an application to amend its Tavium registration on August 12, 2020, including a
request that the upcoming expiration date be extended.
9

 The documents supporting the decision to grant these applications can be found in docket number
EPA-HQ-OPP-2020-0492 at regulations.gov. In coming to its decision, EPA’s record includes
consideration of earlier submitted relevant studies and information as well as new studies and
information received post the earlier registration actions. Therefore, some documents that were
considered in earlier registration actions are referenced in these new supporting documents.
V. Stakeholder Feedback
The Agency received comments from various stakeholders in the form of calls, emails, and
letters concerning the use of dicamba on DT cotton and DT soybeans. The comments were both
in favor of and opposed to the continued or renewed registration of dicamba for pre- and
postemergent use on DT cotton and DT soybeans.
Included in these comments was correspondence from a variety of stakeholders seeking to share
their experience with dicamba, including state agencies, farm bureaus, industry, growers, nongovernmental organizations, academia, congressional committees, and Members of Congress.
These correspondences can be found in the document titled 2020 Dicamba Decision Comments
on regulations.gov in Docket ID: EPA-HQ-OPP-2020-0492. The information provided different
viewpoints, and EPA considered these comments prior to approving these registration actions.
Many letters representing significant economic sectors strongly encouraged EPA to register these
products. These letters indicated that growers need as many tools as possible and that dicamba
for use in DT cotton and soybean is critically important to combat troublesome weeds (Palmer
amaranth). Some of the letters provided information about the adoption rate of this technology as
an indicator of importance to growers and how regulation can hamper the development of new
technologies to help growers control weeds. As of October 19, 2020, examples of letters received
were from agricultural coalitions from the states of: Alabama, Georgia, Kansas, Mississippi,
Nebraska, Virginia; seed dealers/Co-Ops: Beck’s Hybrids, LG Seeds, Wilbur-Ellis, Proseed,
Latham High-Tech Seeds; commodity groups: National Cotton Council (NCC), American
Soybean Association (ASA), Georgia Cotton Commission, Plains Cotton Growers, American
Seed Trade Association; commercial applicator groups: Southern Crop Protection Association
(SCPA); registrant representatives: Crop Life America; governmental entities: Iowa Department
of Agriculture and Land Stewardship, Kansas Department of Agriculture, Pennsylvania
Department of Agriculture, the Governor of Nebraska, the U.S. House of Representatives
Committee on Agriculture, and Members of Congress; and state organizations: the National
Association of State Department of Agriculture (NASDA) and American Association of Pest
Control Officials (AAPCO). There were also letters from various individuals, including one
academic who stated that the DT system is an important tool, but there have been incidents
despite mitigation measures, and additional control measures should be considered (Hartzler).
Letters from other stakeholders provided varying details describing incidents and views on the
nature of incident reporting, including possible underreporting. These letters describe damage to
vineyards, non-DT soybeans, and numerous species of trees and other broadleaf herbaceous
plants. These incidents were documented on small farms, residential areas, public lands (e.g.,
parks, natural areas, wildlife refuges), industrial landscapes (e.g., cemeteries and business store
fronts) and roadsides. Additionally, the issue of “right to farm” was raised (i.e., growers have the
10

 right to grow crops without concern for loss or damage to an organic or sensitive crop because of
offsite movement of dicamba). In addition to concerns about effects to single-season crops,
letters also cited concerns about long-term economic impacts of dicamba damage to orchards and
vineyards. These letters were received from a coalition for specialty crop growers (Save our
Crops Coalition); non-governmental organizations: Audubon Arkansas, National Wildlife
Federation, Prairie Rivers Network, The Land Connection, and Center of Food Safety; a state
organization: American Association of Pest Control Officials (AAPCO); and various
individuals.
VI. Risk Assessments
A. Human Health
The potential for human health risks from OTT uses of dicamba was first assessed in March
2016 9. At that time, EPA found the toxicology database for dicamba complete and sufficient for
assessing the toxicity and characterizing the hazard of dicamba.
In 2020, EPA became aware of mutagenicity studies not previously submitted as well as a new
dicamba epidemiology study conducted as part of the Agricultural Health Study (AHS). 10 The
AHS study reported an association between dicamba exposure in pesticide applicators and
increased risk of liver and intrahepatic bile duct cancer. EPA reviewed this study and identified
several deficiencies. EPA notes an earlier incident/epidemiological memorandum 11 that reviewed
a study which investigated cancer incidence among pesticide applicators exposed to dicamba
which concluded that “Exposure was not associated with overall cancer incidence nor were there
strong associations with any specific type of cancer.” The AHS study does not alter EPA’s
earlier findings because it does not provide any additional information, therefore, the EPA
human health risk conclusions for dicamba remain unchanged since the original assessment in
2016.
Several additional studies addressing dicamba mutagenicity were also reviewed in 2020,
including two comet assays, a kinetics assay, and a transgenic mouse assay. The results do not
impact or change the current cancer classification or risk conclusions for dicamba, which are
summarized in the document Dicamba: Consideration of Newly Submitted Mutagenicity Data and
Human Health Risk Assessment Summary (available on regulations.gov, Docket ID: EPA-HQOPP-2020-0492). Because there was no change in EPA’s cancer classification as “Not Likely to
be Carcinogenic to Humans,” EPA determined that no additional human-health focused control
measures were necessary for these actions.
B. Ecological

See Dicamba and Dicamba BAPMA Salt: Human Health Risk Assessment for Proposed Section 3 New Uses on
Dicamba-tolerant Cotton and Soybean (available on regulations.gov, Docket ID: EPA-HQ-OPP-2016-0187)
10
See https://aghealth.nih.gov/about/
11
See Dicamba: Tier I (Scoping) Review of Human Incidents and Epidemiology (available on regulations.gov,
Docket ID: EPA-HQ-OPP-2016-0223)
9

11

 A summary of the environmental fate and ecological effects, and potential environmental risks
from the pre- and postemergent uses of dicamba on DT cotton and DT soybeans is provided
below. The full assessment can be found in EPA’s 2020 Ecological Assessment of Dicamba Use
on Dicamba-Tolerant (DT) Cotton and Soybean Including Effects Determinations for Federally
Listed Threatened and Endangered Species (available on regulations.gov, Docket ID: EPA-HQOPP-2020-0492).
The ecological assessment for these registration actions included a screening-level risk
assessment for the pre- and post-emergent uses of dicamba on DT cotton and DT soybeans. The
Agency also included species-specific assessments for threatened and endangered (hereafter
referred to as “listed”) species present within the 34 states approved in these registration actions
(Alabama, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Illinois, Iowa, Indiana,
Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska,
New Mexico, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma,
Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia and
Wisconsin).
Dicamba is an herbicide in the Benzoic Acid family that is used for selective control of emerged
broadleaf weeds. In addition to the dicamba parent, the major degradate of toxicological concern
produced under anaerobic conditions for all dicamba products is 3,6-dichlorosalicylic acid
(DCSA). DCSA is persistent, accounting for > 60% of the applied dicamba after a year in an
anaerobic laboratory-based environment. DCSA is also formed in aerobic soil under laboratory
conditions at a maximum of 17.4% of the applied parent dicamba. DCSA is not persistent when
formed under aerobic conditions and degrades roughly at the same rate as the parent dicamba
(8.2 days). DCSA is less toxic or equally toxic as the parent for aquatic organisms on an acute
basis but may be substantially more toxic on a chronic basis to terrestrial organisms, specifically
mammals. Therefore, EPA’s assessment considered the parent and its degradate DCSA in the
aquatic assessment (with the assumption that dicamba and DCSA are equally toxic), while the
terrestrial assessment for mammals considered parent dicamba and DCSA separately.
Ecological Risk Assessment (not including listed species):
EPA’s conservative screening level assessment relies on the risk quotient (RQ) where a measure
of exposure is divided by a measure of effect. The RQ is then compare to a Level of Concern
(LOC) depending on whether the taxonomic group is located in terrestrial or aquatic habitats and
whether the route of exposure is for an acute or chronic exposure duration 12. EPA’s conservative
screening level assessment found no risks of concern for: aquatic animals or aquatic plants, or
terrestrial animals from the inhalation of volatile emissions of dicamba. For non-listed non-target
wildlife located on the treated soybean or cotton field, potential acute dietary risk concerns for
birds (on treated soybean and cotton fields; RQs up to 2.1 compared to a LOC of 0.5) and
potential dietary chronic risk concerns for birds (treated soybean fields only; dicamba based RQs
up to 0.35 and DCSA degradate-based RQs up to 1.7 compared to a LOC of 1), chronic dietary
risk concerns for mammals (treated soybean fields only; dicamba-based RQs up to 0.79 and
DCSA degradate-based RQs up to 3.3 compared to a LOC of 1) and individual bees and other
EPA’s Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S.
Environmental Protection Agency: Endangered and Threatened Species Effects Determinations

12

12

 terrestrial invertebrates (on treated soybean and cotton fields; RQs 1.3-2.4 compared to a LOC of
1). Given the herbicidal action of dicamba, available laboratory toxicity endpoints, and intended
effect of application at the treatment site, risk to nontarget plants within the confines of the
treated soybean or cotton field is expected.
Determining Distances to Effects and Appropriate Infield Buffers
In its assessment, EPA reviewed multiple field-level and laboratory studies from a variety of
sources (registrants, academics, and published literature) to conservatively select effects
endpoints protective of off-field effects to non-target plants and establish conservative estimates
of the potential distances to these endpoints. More information on this is available in the
assessment and its associated appendices 2020 Ecological Assessment of Dicamba Use on
Dicamba-Tolerant (DT) Cotton and Soybean Including Effects Determinations for Federally
Listed Threatened and Endangered Species (available on regulations.gov, Docket ID: EPA-HQOPP-2020-0492).
Spray Drift Evaluation
EPA’s evaluation of the potential for off-field (near field and wide area) transport of dicamba by
spray drift and volatility informed the finding that mandatory control measures on the product
labeling were necessary to approve these registrations. The product labels list multiple spray
drift reduction requirements, including a 240-foot downwind in-field spray drift buffer (i.e.,
applications may only occur at distance greater than or equal to 240 ft within the downwind
boundary of the treated field). This in-field downwind buffer requirement eliminates risk
concerns outside of the treated field for non-listed mammals, birds, terrestrial phase herpetic
species, and terrestrial invertebrates with greater than 90 percent certainty. The same spray drift
requirements (namely the 240 ft in-field buffer) eliminate risk concerns outside of the treated
field for conservatively established non-target plant effects to non-listed species with 90 percent
certainty.
Use of hooded sprayers also has the potential to reduce spray drift and therefore change what
other control measures are necessary to achieve the same results. A hooded sprayer is an
example of a drift reduction technology that can cover the entire spray boom and shields
pesticide droplets from the wind from the height of release to the canopy reducing the potential
for pesticide drift. EPA has received data on tests of a particular hooded sprayer (RedBall 642E)
which demonstrated a substantial reduction in spray drift. A limited number of field studies on
bare soil and soybean crops were conducted and the data received indicate dicamba drift would
be limited to approximately 20 ft from the point of application. These data show great reductions
in the possible movement off-field when using this particular hooded sprayer, but based on the
limited information provided to EPA, the Agency determined that a 5X safety factor would
address the uncertainties with this limited set of data. Therefore, the use of this hooded sprayer
would allow the 240-foot in-field spray drift buffer to be reduced to 110 feet and still be
protective of non-listed plant species with a high level of confidence (see section IX for
discussion of the spray drift buffer zone distance when using hooded sprayers in areas where
listed species are present). It should be noted that these trials did not evaluate the use of other
types of sprayers (alternative hooded broadcast, hooded in-row and layby sprayers) nor did they
evaluate the use of a hooded sprayer over cotton crops. As a result, the reductions in buffer
13

 distance permitted when using hooded sprayers is limited to this one sprayer for use on soybean
crops. Additional brands or models of hooded sprayers can qualify for the reduced downwind
buffers for soybeans if they meet the performance standard established by testing according to
EPA’s approved protocol in comparison to the currently assessed hooded sprayer. Hooded
sprayers eligible for the reduced downwind buffers for soybeans will be listed on the registrants’
websites; only those hooded sprayers so listed are eligible for the reduced downwind
buffers. downwind buffers.
Volatility Evaluation
Field data using dicamba products for use on DT crops without the addition of any VRAs (pH
buffering adjuvants) to tank mixes indicate the potential for risk to non-target non-listed
terrestrial plants from exposure to volatile emissions beyond the field’s edge. Importantly, when
certain VRAs (pH buffering adjuvants) are included in the tank mix, laboratory and field studies
demonstrate much lower dicamba volatility. Based on many studies, EPA determined that the
volatile emissions would not go beyond the field’s edge with a high degree (89%) of certainty.
An evaluation of incident data, coupled with laboratory and field-based volatility data, shows
that avoiding application when air temperatures are favorable to volatility would decrease the
conditions that may have led to some dicamba-related non-target plant incidents. The imposition
of mandatory application cut-off dates (June 30th soybean, July 30th cotton) on the product labels
reduces the probability of dicamba application on days more favorable for dicamba
volatilization. The June 30 and July 30 dates were informed by data on the effect of temperature
on volatility. EPA utilized historical incident information and meteorological data to conduct its
analysis. First, EPA compared the maximum temperature data on the day of each reported
incident and determined that over 94% and 82% of the incidents occurred at temperatures above
75 oF and 80 oF, respectively. EPA then reviewed historical meteorological data to determine the
proportion of total days less than 75 oF and 80 oF. Based on this analysis, the soybean cut-off of
June 30th would mean that application temperatures will be below 80 oF between 12% (Texas) to
89% (Minnesota) of the time, and below 75 oF between 3.2% (Texas) to 72% (Minnesota) of the
time. The cotton cut-off of July 30th would mean that application temperatures will be below 80
o
F, between 8% (Florida) to 66% (Virginia) of the time, and below 75 oF between 0.3% (Florida)
and 36% (Virginia) of the time. EPA notes that this analysis did not consider the impact of the
mandatory VRA (pH buffering adjuvant) combined with the cut-off date.
When considering favorable volatility temperatures in the context of crop planting schedules and
meteorological data, labeled dicamba application cutoff dates reduce applications coinciding
with temperatures favoring dicamba volatility and by extension incidents. Because the dates are
the same in all 34 states and the meteorological data vary across these geographies, the
magnitude of the protective certainty of cut-off dates is not uniform across the 34 states, but in
no state was the probability of avoiding a threshold temperature on the day of application zero.
The use of a cut-off date produced avoidance of applications of dicamba on days with
temperatures favoring volatility and is expected to provide protection of both effects at the near
field level as well as on scales suggested by available incident data.

14

 VII. Benefits and Impacts Assessments
In accordance with FIFRA, EPA considers both risks and benefits when considering the
registration of a given pesticide. A summary of the assessed benefits of dicamba use on DT
cotton and DT soybeans, and the impacts of these registration actions appears in this section. To
see EPA’s current assessment of the benefits and impacts of dicamba use in DT crops, please
refer to Dicamba Use on Genetically Modified Dicamba-Tolerant (DT) Cotton and Soybean:
Incidents and Impacts to Users and Non-Users from Proposed Registrations;
Assessment of the Benefits of Dicamba Use in Genetically Modified, Dicamba-Tolerant Soybean
Production; and Assessment of the Benefits of Dicamba Use in Genetically Modified, DicambaTolerant Cotton Production (available on regulations.gov, Docket ID: EPA-HQ-OPP-20200492).
A. Benefits of the Registration of Dicamba Use in DT Cotton and DT Soybeans
Cotton and soybeans are extremely important agricultural commodities in the U.S. USDA
estimates the gross value of soybean production at approximately 40 billion dollars in the United
States, and the gross value of cotton production at 6.6 billion dollars in the United States. 13
USDA’s Economic Research Service describes soybeans as the world’s largest source of animal
protein feed and the second largest source of vegetable oil and describes cotton as one of the
most important textile fibers in the world, accounting for around 25 percent of total world fiber
use. The United States is the world’s leading soybean producer and second leading exporter, and
soybeans comprise about 90% of the United States’ oilseed production. Between 2014 and 2017,
soybean production, processing, and use, including biodiesel and livestock feed, generated about
$115.8 billion in economic activity, supporting the equivalent of 280,000 full-time jobs 14. The
United States is the world’s third-largest cotton producer and the leading cotton exporter,
accounting for one-third of global trade in raw cotton. Per USDA’s Economic Research Service,
the U.S. cotton industry accounts for more than $21 billion in products and services annually,
generating more than 125,000 jobs in the industry sectors from farm to textile mill. This does not
include other jobs that may be created further in the supply chain.
Soybean and cotton growers throughout the United States continue to experience crop yield and
economic losses due to the prevalence of herbicide-resistant weed biotypes. For example, when
glyphosate resistant weeds were present in soybeans there was a reduction of $22.50 or 14% of
total returns per planted acres. Herbicide resistance has become a significant financial, production
and pest management issue for many cotton and soybean growers, and agriculture as an industry.
The significant adoption of DT technology is directly responsive to the need to prevent economic
losses, and these products benefit soybean and cotton growers. In some states (i.e., Mississippi),
DT soybean may account for nearly 80% of planted acres; however, nationally, ERS shows a
41% adoption rate in 2018, which is similar to the adoption rate in the primary states producing
13

USDA/NASS. 2020. Quick Stats, searchable database. Query for acreage, production, and value, by state, 20142018. Available at www.nass.usda.gov/Data_and_Statistics/index.php. Accessed March 2020.
14
LMC International Ltd. 2019. The Economic Impact of U.S. Soybeans and End Products on the U.S. Economy,
Report for the United Soybean Board and National Oilseed Processors Association, November. Available at
http://www.nopa.org/wp-content/uploads/2020/03/LMC_U.S.-Soy-Economic-Impact-Study-for-USB_FINAL31320.pdf. Accessed October 2020.

15

 soybean (e.g., Illinois, Indiana and Iowa) 15. ERS shows a DT adoption rate of 69% in cotton in
201915. However, DT soybean or cotton provides growers with the option of using dicamba, but
not all of those growers will ultimately apply dicamba. In 2017 and 2018, growers used dicamba
on 8% and 17% of all U.S. soybean and cotton acres prior to crop emergence, respectively, and
on 17% and 34% of all U.S. soybean and cotton acres after crop emergence, respectively. 16
Dicamba is primarily used to target herbicide-resistant Palmer amaranth, waterhemp, kochia,
ragweed, and marestail in soybeans, and herbicide-resistant Palmer amaranth and redroot
pigweed in cotton, and is effective at controlling a wide range of broadleaf weed species.
For areas where dicamba products cannot be used on DT cotton and DT soybeans, there are
effective alternative weed control programs currently available for the control of problematic
broadleaf weeds in cotton and soybeans. However, the number of postemergence herbicide
options is very limited; therefore, cotton and soybean growers can benefit from the registration
of dicamba for use in DT cotton and DT soybean. The dicamba tolerant system was created to
address weed populations with resistance to glyphosate (Weed Science Society of America
[WSSA] Group 9 herbicide), ALS (acetolactate synthase) inhibitor herbicides (WSSA Group 2)
and PPO (protoporphyrinogen oxidase) inhibitor herbicides (WSSA group 14). The registration
of dicamba in DT cotton and DT soybean will give growers additional flexibility for managing
herbicide-resistant weed populations, thereby prolonging the effectiveness of currently available
control options for herbicide-resistant weed species.
In addition to post emergence application, dicamba in DT cotton and DT soybean has utility
prior to crop emergence. Older, more volatile dicamba products allow preemergent use, but only
with a preplant restriction of a specified number of days and rainfall or irrigation water between
dicamba application and planting to avoid crop injury. Because DT crops are tolerant of
dicamba, these crops do not require preplant restrictions that would otherwise be required to
protect emerging soybean and cotton from dicamba damage; this provides greater flexibility to
growers.
In soybean, a postemergence dicamba-based herbicide program may be less expensive than
alternative herbicide programs. A postemergence dicamba program may reduce grower costs by
$12-$14 per acre (4%-7% of grower net operating revenue, depending on region), not including
the cost of adjuvants or of other mitigation measures relative to some herbicide programs (e.g., a
2,4-D based program). Growers who chose a glufosinate program could see similar costs to the
postemergence dicamba program. In cotton, relative to other alternative herbicide programs,
postemergence dicamba may reduce grower costs by $8-$14 per acre (5%-10% of grower net
operating revenue), not including the cost of adjuvants or of other mitigation measures. Seed
costs and rebates offered by seed and chemical manufacturers can affect the overall cost of the
herbicide program, as can the additional costs of adjuvants.
In certain locations performance of dicamba has been poor owing to dicamba-resistant weed
populations. In areas where Palmer amaranth is exhibiting decreased susceptibility to
dicamba, additional herbicide applications or other weed management measures may be
USDA ERS (United States Department of Agriculture, Economic Research Service), 2020. Special tabulation,
based on the Agricultural Resources Management Survey: Crop Production Practices data. Compiled by Dodson,
Laura.
16
Source: Kynetec, 2019.
15

16

 necessary to achieve adequate weed control where species are experiencing decreased
susceptibility, increasing the cost of the postemergence dicamba program.
Considering all the information, the Agency concludes that the registration of dicamba for use in
DT cotton and DT soybeans will provide growers of these crops with additional flexibility in
choosing products to manage difficult to control broadleaf weeds during the crop growing season.
In cases where there are herbicide-resistant weeds, the Agency finds there are few alternative
postemergent herbicides available for users.
Based on experience, resistance occurs over time and can be expected for many pesticides. When
dicamba resistance spreads, the benefits of dicamba in DT cotton and DT soybean will decrease,
with decreased benefits concentrated in those areas where dicamba-resistant broadleaf weed
species are established. The Herbicide Resistance Management (HRM) plan required as part of
each registration is designed to preserve the efficacy and benefit of this important weed
management tool. EPA believes such plans, including proactive information sharing, represent
the best strategy for managing resistance because they are consistent with recommendations from
experts in the field. These plans include enhanced notification and reporting requirements,
additional education and training requirements, and follow up measures to contain and control as
best as possible the spread of populations identified as resistant or likely to be resistant.
B. Impacts Assessment
Impacts of Registration to Non-Users of Dicamba:
EPA finds negative impacts to non-users from the registration of these OTT dicamba products
will be minimal due to the new control measures addressing drift and volatility. Incidents of
plant damage consistent with exposure to dicamba have been documented in a variety of
sensitive crops including non-DT soybean, fruit trees, and vegetables. The level of damage is
variable and may range from slight leaf cupping to plant death. The level of damage depends on
the magnitude and length of exposure, the number of times exposed, the growth stage of the
affected plants when exposure occurs, and the response of the injured plant after exposure. Not
all of the reports of alleged dicamba damage are associated with yield loss.
Without appropriate controls, the impacts of offsite movement to non-users may be substantial.
High value crops may suffer yield and quality losses, organic growers could lose organic
certification, research and crop breeding programs could be disrupted, and plantings in
residential areas (e.g., home gardens) and landscapes could be damaged. Offsite movement of
dicamba from products registered for use on DT crops that injures adjacent crops has resulted in
conflict between neighbors. Injured parties may make reports to state authorities or sue for
damages. State lead agencies have been receiving drift complaint calls; all of this may create
social impacts which EPA is obligated to consider under FIFRA. EPA approved a suite of
control measures to ensure dicamba stays on the treated field, addressing offsite movement and
therefore the likelihood of damage.
Overall, negative impacts to non-users from the registration of these OTT dicamba products will
be minimal, as the mandatory control measures give EPA a 90% confidence that there will be
no offsite movement of dicamba. Some measures only address one type of offsite movement
17

 (e.g., volatility) while others may address both volatility and particle drift. When used in
combination as required, the suite of control measures has been determined to be protective with
90% confidence.
For example, the calendar-based application restriction (no applications are allowed after June
30th in soybeans and after July 30th in cotton) is intended to limit applications of OTT dicamba to
earlier in the growing season when temperatures are more likely to be cooler than later in the
season. In addition, earlier application can reduce risks because sensitive plants in adjacent areas
may not be in their most vulnerable growth stage. The calendar cut-off dates, in combination
with the mandatory use of the VRA (pH buffering adjuvant), addresses offsite movement from
volatility. While varying temperatures do not have an impact on spray drift, the calendar cut-off
addresses the potential risk from spray drift, because applications are not allowed to be made
later in the season when nearby plants are likely in their reproductive stages and are more
sensitive. Spray drift is also addressed by important control measures including limitations
regarding wind speed, spray droplet size, spray nozzles, and an infield buffer downwind of the
treatment area. When fewer incidents result from volatility and spray drift, more sustainable use
is achieved, preserving states’ limited investigation resources.
Impacts of Control Measures to Users:
Having separate product labels for just DT soybean and DT cotton will simplify use for users and
improve compliance. Several of the control measures on the newly registered product labels may
increase applicator/grower costs and may involve more elaborate user practices than similar
herbicides. For instance, cutoff dates may prevent some growers from making applications for
late season weed control. Mandatory use of adjuvants (VRAs/pH buffering adjuvants and drift
reducing agents) have the potential to increase per-acre costs. Infield buffers will complicate
weed control in the field and adjacent to the field borders. For example, there may be limited
approved alternate herbicides for weed management within the buffer area. Hooded sprayers, if
utilized, may benefit growers by reducing the buffer distance, but would increase the time
needed to make applications because these sprayers require reduced tractor speeds.
VIII. Registration Decision
In accordance with FIFRA section 3(c)(5), EPA must register a pesticide when it finds that the
use will not generally cause unreasonable adverse effects 17 on human health or the environment,
taking into account the economic, social, and environmental costs and benefits of the use of the
pesticide. FIFRA section 3(c)(5) specifically requires approving of a registration if EPA
determines:
(A) its composition is such as to warrant the proposed claims for it;
(B) its labeling and other material required to be submitted comply with the requirements
of this Act;
(C) it will perform its intended function without unreasonable adverse effects on the
environment; and
FIFRA section 2(bb) defines, in pertinent part, “unreasonable adverse effects” as ''any unreasonable risk to man or
the environment, taking into account the economic, social, and environmental costs and benefits of the use of any
pesticide….”
17

18

 (D) when used in accordance with widespread and commonly recognized practice it will
not generally cause unreasonable adverse effects on the environment.
EPA reviewed the compositions of all three products and determined that the claims made are
warranted and the information supports the approval of the registrations. The labeling from the
registrants contains all the necessary requirements and restrictions and complies with the
requirements of FIFRA. EPA received studies and other information, necessary to comply with
the data requirements for the uses of these products. The Agency also reviewed a large body of
data and information to determine how these products have been and will be used to determine
the risks and benefits. All of these evaluations informed EPA’s determination that registering
these products will not generally cause unreasonable adverse effects on the environment when
used in accordance with widespread and commonly recognized practice.
In making a determination as to unreasonable adverse effects, EPA is charged with considering
the economic, social, and environmental costs and benefits of the use of the pesticide. EPA must
determine if the benefits outweigh any potential risks of concern as well as adverse impacts in
order for the Agency to determine the product will not generally cause unreasonable adverse
effects.
In the case for the use of dicamba on DT soybeans and DT cotton, and in consideration of all
best available data and assessment methods, the EPA determines that registering these uses
would meet the requirements of FIFRA.
The database submitted to support the assessment of human health risk is sufficient for a full
hazard evaluation and is considered complete and adequate to evaluate risks to the general
population including infants and children. The Agency has not identified any risks of concern for
human health, including all population subgroups, or for occupational handlers. EPA also
considered the potential for risks to plants and wildlife, and identified control measures
appropriate to address those risks and consideration of benefits and impacts of the use, as
discussed in the next section.
A. Addressing Ecological Risk under FIFRA
In EPA’s screening level ecological assessment, the Agency found some risks to certain wildlife
on the treated fields. These include birds, mammals, and bees and other invertebrates. These
assessments included conservative risk estimates using screening-level assumptions that assume
maximum exposures to the birds, mammals, bees and other invertebrates. For example, the risk
assessment assumes that the wildlife will forage exclusively in the treated area, which is a
conservative assumption and will overestimate risk for the majority of wildlife utilizing
agricultural fields.
The risk assessment presumes that if there were non-dicamba tolerant plant species on treated
fields, given the herbicidal mode of action of dicamba, those plants would be at risk. Because
growers that use dicamba for weed control are managing their fields for the highest level of
production of soybean or cotton on their own land, EPA concluded that any non-tolerant plants
would be considered a target pest and therefore there would be no non-target plants on the fields,
except for the DT crops.
19

 Based on the mandatory control measures to address spray drift and volatility, EPA determined
that risks are restricted to those individuals in the treated fields and there are no risks of concern
for birds, mammals and bees or other invertebrates outside of the field with greater than 90%
certainty. EPA identified risks of concern for non-target plants via runoff in adjacent areas.
While control measures to address runoff risk to plants are included in the labeling, EPA
concluded that these measures reduce but do not eliminate risk. For plant risk from spray drift
and volatility, EPA concluded that risks were below levels of concern, taking into account the
mandatory control measures, at the 90% and 89% confidence level, respectively, based on
conservative plant effects endpoints.
Additionally, in making determinations under FIFRA, EPA considers the benefits in order to
determine whether any remaining risks are unreasonable. EPA considered the fact that herbicide
resistance has become a significant financial, production and pest-management issue for many
cotton and soybean growers and concluded that dicamba will be a cost-effective way to control
herbicide-resistant broadleaf weed species and delay the further development of herbicide
resistance. Based upon those considerations, EPA has determined that the benefits outweigh the
remaining risks to wildlife and plants on treated fields and nearby.
EPA has determined that the mandatory control measures on these registrations address spray
drift and volatility. In order to determine the appropriate control measures, the Agency did
consider whether there could have been risks of concern outside the treated field without these
measures. Over the period in which the OTT uses of dicamba have been available, many reports
of off-site movement on agricultural land and alleged crop injury have been received from state
agencies, agricultural researchers, and growers. Although not as widely reported, off-site plant
damage in natural areas and in residential and commercial properties has also been reported and
alleged to have occurred due to off-field transport of dicamba by spray drift and volatility.
EPA’s registrations have extensive mandatory control measures on the labels to address spray
drift and volatilization which are further described below.
An important example of a mandatory control measure is the cutoff date of June 30 and July 30
for the postemergent applications of the dicamba products use in DT soybeans and DT cotton,
respectively 18. Certain conditions that may promote higher volatility, such as higher
temperatures, increase as the summer months progress. These conditions may increase the
movement of dicamba as a result of an increase in volatility. Prohibiting applications later in the
season when temperatures are higher will directly address this issue. In addition, nearby nontarget crops are less likely to be at vulnerable growth stages earlier in the season, so limiting the
use of dicamba to early season application will further reduce crop injury in neighboring areas.
In the September 2020 AAPCO survey, some states have issued cutoff dates 19 for dicamba OTT

EPA considered regional cutoff dates as well as temperature thresholds as alternatives and determined that a
nationwide cutoff offers the greatest label clarity.
19
FIFRA section 24(a) allows a state to regulate pesticides more restrictively than EPA under the state’s own
authority. However, some of the states that have imposed cut-off dates on dicamba uses have done so under section
24(c). Section 24(c) only authorizes states to issue registrations for additional uses of federal registrations to meet
special local needs; if states wish to impose further restrictions on the dicamba products, or any other federally
registered pesticides, they should do so under section 24(a) of FIFRA
18

20

 use in soybeans in their states and associated the cutoff date with lowering levels of offsite
dicamba movement and damage.
To further address volatility, the label requires an important new mandatory control measure
requiring users to add an approved VRA (pH buffering adjuvant) to the tank with every
application of the product. This results in the spray solution having a higher pH and therefore
less volatility. Specific VRAs (pH buffering adjuvants) have been tested with rigorous scientific
data that supports this determination. By stabilizing the pH in the spray solution, the lower
volatility characteristics of these products are preserved, reducing the risk of pH changes that
result in higher volatility with the addition of other components to the spray mix.
Based on rigorous review of all the scientific information, EPA has determined that an increased
infield buffer was necessary to address spray drift and to protect non-target plants. Based on
conservative regulatory endpoints, these labels include a mandatory downwind buffer of 240 ft
(310 ft in areas where it is necessary to protect listed species as described in Section IX).
In addition to the enhanced new control measure approach described above, the labels also
involve a simpler format that is easier to understand and follow, which will help to prevent
potential misuse of these dicamba products for use on DT crops. Importantly, these products are
registered for use on DT soybean and cotton crops only, thereby minimizing the confusion from
earlier labels that contained more than just these two DT crops. By restricting use only on DT
soybean and cotton crops, the restrictions and requirements of the label can be very
straightforward and prominent for the user and make enforcement easier for state regulatory
officials. In addition, the labels have been rewritten and reformatted to make the restrictions very
clear and apparent, which also clarify the requirements of the label.
Other important control measures will continue to help address risks of damage from off-site
movement, such as restricted use classification, strict training and recordkeeping requirements,
time-of-day restrictions, and temperature-inversion restrictions. The overlapping risk control
measures minimize the potential risks of movement and any associated damage posed by these
dicamba products and enable the utilization of a very important tool to control extremely
problematic herbicide-resistant weeds.
In addition to the mandatory control measures, EPA is supporting the adoption of the latest drift
reducing technology because greater use of such technology could be useful in mitigating risks
for a variety of pesticides. As such, and supported by data on soybeans, EPA is allowing the
option of using an approved-hooded sprayer with reduced downwind spray drift buffers of 110 ft
in areas with no listed species and 240 ft in areas with listed species for soybeans only. These
buffer distances were informed by data from field studies showing dicamba drift was confined to
approximately 20 feet. Owing to the limited database and to ensure protection, EPA applied
conservative safety factors to select 110 ft and 240 ft infield downwind buffers for non-listed
species and for listed species, respectively, when using a qualified hooded sprayer on soybeans.
As more data becomes available in the future, EPA will consider applications to amend the
registrations to allow smaller buffers, and/or to allow reduced buffers for cotton.
On the benefits side of the analysis, use of dicamba on DT soybeans and DT cotton is an
important part of a resistance management strategy. Soybeans and cotton are extremely
21

 important agricultural commodities in the United States and the world. According to the USDA’s
National Agricultural Statistics Service, soybeans are harvested from approximately 84.8 million
acres and cotton is harvested from approximately 9.3 million acres. USDA’s Economic Research
Service describes soybeans as the world’s largest source of animal protein feed and the second
largest source of vegetable oil and describes cotton as one of the most important textile fibers in
the world, accounting for around 25 percent of total world fiber use. The United States is the
world’s leading soybean producer and second leading exporter, and soybeans comprise about
90% of the United States’ oilseed production. The United States is the world’s third-largest
cotton producer and the leading cotton exporter, accounting for one-third of global trade in raw
cotton. The U.S. cotton industry accounts for more than $21 billion in products and services
annually, generating more than 125,000 jobs in the industry sectors from farm to textile mill.
Weed control experts warn that the problem of herbicide resistance is increasing, and that
significant economic consequences will continue to increase without effective alternatives for
weed control. In addition, the use of dicamba, when used as part of a season-long weed
management program that includes preemergence (residual) and postemergence (foliar)
herbicides, provides a long-term benefit as a tool to delay resistance of other herbicides as well.
Use of dicamba on DT soybeans and DT cotton is beneficial as it provides an effective tool to
treat especially problematic weeds, such as marestail, giant ragweed, common waterhemp, and
Palmer amaranth, including glyphosate-resistant biotypes that threaten soybean and cotton
production today. For example, when glyphosate resistant weeds were present in soybeans there
was a reduction of 14% of total returns per planted acres. By adding an effective tool to combat
glyphosate-resistant and other weeds, dicamba can help reduce this difficult weed pressure and
aid significantly in production, reducing economic losses to soybean and cotton growers. In
addition, effective treatment of glyphosate-resistant weeds can help control the spread of
resistance. EPA finds these benefits significant and important for mitigating production and
economic losses for these growers.
After weighing the risks of concern mentioned earlier against the benefits of these uses, EPA
finds that when the required control measures for these uses are applied, the benefits of the use of
the pesticide outweigh the risks. Therefore, registering and renewing these products will not
generally cause unreasonable adverse effects on human health or the environment and therefore
meets the FIFRA Section 3(c)(5) registration finding for these registrations.
Therefore, EPA will be registering two end use dicamba products (EPA Registration Numbers
264-1210 and 7969-472) and extending the registration for one dicamba product (EPA
Registration Number 100-1623), all for applications only on DT cotton and DT soybeans, with an
automatic expiration date of December 20, 2025. As part of these registrations and registration
extension, EPA is requiring label language as described in Section VII B Label Requirements.
When used in accordance with the control measures on the product label, EPA expects that this
registration action will not generally cause unreasonable adverse effects to human health or the
environment.
B. Label Requirements
The labels approved by EPA for these products contain certain control measures for dicamba use
on DT cotton and DT soybean, including additional control measures to protect listed species.
This includes both enforceable as well as advisory statements. The only currently available
22

 products for use on DT cotton and DT soybeans are Tavium, XtendiMax, and Engenia (EPA
Registration Numbers 100-1623, 264-1210, and 7969-472). The specific labeling requirements
for these dicamba product labels with registered uses on DT cotton and DT soybeans are outlined
here.
New Registrations are for DT-Crops Only:
Previous registrations of dicamba for use on DT crops also included label directions for use on
many other non-DT crops such as asparagus, corn, turf, sorghum, and sugarcane, including
directions for use on non-DT soybeans and DT cotton. This led to complicated and lengthy
labeling.
The new approved labeling for Engenia, XtendiMax, and Tavium includes only directions for
use on DT cotton and DT soybeans.
Certified Applicator Provision:
These products are restricted use pesticides (RUP) and include a provision that they may only be
used by certified applicators. Because the Agency finds that the complexity of the chemistry
warrants ensuring that only the most highly trained individuals apply it, individuals who are not
themselves certified applicators may not make an application of dicamba to DT crops, even
under the direct supervision of a certified applicator. By ensuring only those individuals with the
highest level of pesticide application training may make such applications allowing the tool to be
available for growers.
Record Keeping Requirements:
As RUPs, these products include record keeping requirements that certified applicators must
generate as soon as practical but no later than 72 hours after application. The certified applicator
must keep these records for a period of two years. In addition to records that certified applicators
are already required to keep, records specific to the application of the products for use on DT
crops are required, including information concerning the VRA (pH buffering adjuvant) used,
application date, proof of training, and infield buffer distances observed.
Mandatory Applicator Training:
The labels include a dicamba-specific training requirement. Strong training requirements will
reduce the likelihood of application errors.
Mandatory Tank Mix with Volatility Reduction Adjuvant(Agent)/pH Buffering Adjuvant:
All applications of XtendiMax, Engenia, and Tavium must be applied in a tank mix with an
approved VRA (pH buffering adjuvant). Users are directed to a registrant website that lists
approved VRAs (pH buffering adjuvant). The proper use of the required VRA (pH buffering
adjuvant) is also covered in the mandatory dicamba-specific training.
Calendar Date Cut-off:
The labels prohibit application after June 30 and July 30 for DT soybeans and DT cotton,
respectively. Previous dicamba registrations for DT crop use only allowed use on cotton prior to
mid-bloom stage or no more than 60 days after planting, whichever occurs first, and on soybeans
prior to beginning bloom (R1 stage) or no more than 45 days after planting, whichever occurs
first. To simplify labeling and improve consistency, new restrictions replace these previous
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 prohibitions to address dicamba risk, whereby applications to DT soybeans may not occur after
June 30th, and applications to DT cotton may not occur after July 30th.
Inversion (Sunrise/Sunset Timing) Restriction:
The labels contain a control measure that prohibits application during temperature inversions,
and a time-of-day restriction that requires applicators to only apply between one hour after
sunrise and two hours before sunset. This restriction will reduce applications being made at times
of day when temperature inversions often occur.
Equipment Clean-out Instructions:
Poor practices for maintaining pesticide application equipment may lead to cross-contamination.
Because even trace amounts of dicamba can cause crop injury, residues that are accidentally left
in application equipment can carry over to subsequent applications to non-dicamba tolerant
crops. The labels include equipment clean out instructions and advisory language on the subject
of application equipment hygiene. Additionally, the training covers equipment cleanout.
Buffers:
The labeling includes a 240-foot downwind in-field buffer. Also, the labeling includes a Listed
Species Protection Requirement of a 310-foot downwind in-field buffer and an omnidirectional
in-field buffer of 57 feet in areas where listed species are present. To determine if a particular
area is subject to the 310-foot downwind in-field and 57-foot omnidirectional in-field buffer
restrictions, applicators must check Bulletins Live! Two (BLT) prior to making an application.
Instructions on how to access Bulletins Live! Two are included on the label. EPA is in the
process of updating Bulletins Live! Two. In addition, the label allows the optional use of
approved hooded sprayers with a 110-foot in-field spray drift buffer, and 240-ft in-field buffer in
areas with listed species, for soybeans only. Any approved hooded sprayers will be listed on the
registrant websites for each product.
In addition to the in-field buffers described above, in all areas, application is prohibited when
sensitive crops or certain plants are immediately downwind.
Advisory Language/Best Management Practices:
In addition to the mandatory label language, there are advisory statements on factors that can
further protect against the potential for off-target movement of dicamba.
C. Terms of Registration
As part of its decision to register and extend a registration of dicamba for use on DT cotton and
DT soybeans, the registrants have agreed to certain terms as elements of the registration. These
terms will include monitoring requirements, an herbicide resistance management plan,
requirements for adding additional VRAs (pH buffering adjuvants), requirements for adding
additional tank mix partners, and requirements for adding hooded sprayers that can be used in
order to obtain reduced infield buffer distances.
Monitoring Requirements
The Agency is specifying various monitoring requirements that will aid EPA in assessing both
the market for dicamba products registered for OTT uses and the impacts of the new control
measures included in this decision. The Agency’s monitoring requirements for dicamba use on
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 DT crops are listed below:
1. Enhanced incident reporting that aggregates reports of potential damage to non-target
vegetation.
2. Information concerning dicamba-resistant weeds and cases of weed control failure.
3. Information by state and acres regarding sales of product used for OTT dicamba
applications.
Herbicide Resistance Management Plan
The EPA is issuing this registration with a term that requires the registrants to conduct education
and training and maintain an Herbicide Resistance Management (HRM) Plan. The HRM
requirements strengthen the notification and reporting requirements, include additional education
and training requirements, and requires enhanced follow up measures to contain and control, as
best as possible, populations identified as resistant or likely to be resistant. The education
program focuses on educating growers on the appropriate use of the products for OTT use on DT
crops and the associated dicamba-tolerant seeds. The EPA is requiring that the HRM plan include
measures that will reduce the potential for the development of weed resistance, including the
investigation of lack of herbicide efficacy, engagement with growers to control and prevent
spread of “likely resistance”, annual reporting to EPA, reporting of “likely resistance” to other
interested parties, and educational programs to provide growers with the best available
information on herbicide resistance management.
Requirements for Additional Volatility-Reduction Adjuvants/Agents (pH Buffering Adjuvants)
The VRAs (pH buffering adjuvants) mandated for use as a tank mix when applying these
products have been tested with scientific data to verify their efficacy in reducing off-site
movement due to volatility. Because it is critically important to ensure that this reduced volatility
is maintained, any additional VRA (pH buffering adjuvants) proposed for this use must also be
proven with acceptable testing methods to ensure the same level of volatility-reduction before
they can be approved for use. Strict testing protocols are required for this purpose. VRAs (pH
buffering adjuvants) that are deemed acceptable after being tested with these protocols may then
be added to a website maintained by the registrant that lists the approved options for tank mix
partners available for use with their product.
In addition, because the number of VRAs (pH buffering adjuvants) deemed acceptable for these
uses may be limited after the initial registration in the immediate future, additional terms are
added requiring the registrants to provide assurance that these VRA/pH buffering adjuvants will
be available in amounts sufficient to ensure availability for lawful use with all dicamba products
released for use on DT crops.
Requirements for Additional Tank Mixes
Additional components to an application solution are commonly used for a variety of reasons,
including reducing costs and increasing efficacy. Because the addition of tank mix partners can
affect the drift potential of the resulting spray solution, potential tank mix partners must first be
tested with wind tunnel data to ensure that higher drift potential does not occur as a result of
applying the mixture. Strict wind tunnel testing protocols are required to verify that tank
mixtures will not increase drift potential before they can be approved for actual field use.

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 Requirements for Qualifying Additional Hooded Sprayer Equipment for Reduced Infield Buffers
The Agency encourages the use of drift reduction techniques as a general risk management
technique with any pesticide application. Hooded sprayers are an equipment option that can
provide significant drift reduction benefits to agricultural pesticide applications. However,
different types of hooded sprayers can provide different levels of drift reduction. A reduced
downwind buffer has been approved for these products in association with the use of certain
hooded sprayers after acceptable data demonstrated that this reduction is appropriate. For
additional hooded sprayers to be similarly approved for use with reduced downwind buffers, they
must first be tested using the specific testing protocols required for this purpose.
D. Registration Expiration
EPA’s determination that the benefits of the use of dicamba on DT cotton and DT soybeans
outweigh the potential risks is based in part on the requirement that EPA Registration Numbers
264-1210, 100-1623, and 7969-472 automatically expire on December 20, 2025, unless the EPA
takes further action to amend the registration. As noted in Section VII of this decision, approving
the registration of dicamba use on DT cotton and DT soybeans until December 20, 2025 will
enable cotton and soybean growers to have continued access for at least a limited time for a tool
that is important to control glyphosate-resistant weeds, while simultaneously allowing EPA and
states to monitor the impacts of the new control measures and positioning the Agency to be
responsive to any unexpected impacts.
E. Geographic Limitation of the Registration
Dicamba products registered for use on DT cotton and/or DT soybeans may only to be sold and
used in 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.
IX. EPA’s Effects Determinations under the ESA
In order to protect listed species, EPA conducted species-specific analyses to make its effects
determinations under section 7(a)(2) of the ESA for these registration actions. The ESA effects
determination makes use of the best available scientific information and considered both direct
and indirect effects. These analyses and effects determinations are contained in 2020 Ecological
Assessment of Dicamba Use on Dicamba-Tolerant (DT) Cotton and Soybean Including Effects
Determinations for Federally Listed Threatened and Endangered Species (available on
regulations.gov, Docket ID: EPA-HQ-OPP-2020-0492). The listed species effects determination
evaluates whether the federal action poses any discernible effects to listed species and any
designated critical habitats that are reasonably expected to occur within the action area. The
following summarizes these determinations.
In conducting this effects analysis, EPA used the methods described in the EPA’s Overview of
the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental
Protection Agency: Endangered and Threatened Species Effects Determinations (USEPA 2004),
and relied on location information provided by NMFS and USFWS (collectively referred to the
Services),for the purposes of establishing whether listed species and any designated critical
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 habitats occur within the action area for these pesticide registration actions. EPA also used the
Services published materials describing the biology and behavior of the species and the
characteristics of any designated critical habitats.
EPA used the best available scientific information related to dicamba effects on non-target plants
and animals. These include: 1) pesticide registrant submissions to the EPA, 2) published
scientific literature, 3) submissions to the EPA from various academic researchers, and 4) nongovernmental organization submissions. Where applicable, EPA relied on conservative taxaspecific risk assessment methods and their associated conservative assumptions regarding
pesticide exposure and organism biology and behavior to identify taxonomic groups of nontarget organisms that either 1) are not reasonably expected to be affected by the federal action or
2) require additional evaluation in a more biologically accurate and exposure appropriate species
specific quantitative evaluation.
Taxonomic groups considered unaffected by the federal action include the aquatic taxa: fish and
amphibians, invertebrates, and multicellular plants. Aquatic unicellular plants were identified as
a possible taxon for additional evaluation for effects to listed species, however no unicellular
plants are identified by the Services’ as listed species, so no further effects determination
refinement efforts were necessary for this taxon. Terrestrial mammals and birds (and reptiles as
well terrestrial phase amphibians) and invertebrates were identified as taxa requiring effects
determinations. For these animal taxa, EPA assessed whether the listed species would be
reasonably expected to occur within the borders of the treated crop field (i.e., the action area).
Once the listed species were determined to be in the action area, EPA assessed whether there
were any discernible effects to these species.
In contrast to animals, effects to terrestrial non-monocot plants have the potential to be more
geographically extensive without mandatory dicamba control measures. Available data indicated
that, without these measures, these effects may extend beyond the treated field. EPA reached
this preliminary finding after consideration that 1) non-monocot plants were the most sensitive
taxa to dicamba exposure and therefore likely to define the boundaries of the action area, 2) the
large number reports of plant incidents related to off-field dicamba exposure, and 3) the
availability of a large body of evidence characterizing the plant effects associated with transport
of dicamba from the treatment site. Therefore, EPA’s evaluation of risks to non-monocot plants
incorporated more comprehensive methods for risk assessment to characterize the potential for
direct effects on this taxon.
For this ESA assessment, EPA evaluated the mandatory control measures against the following
criteria:
• whether there was any discernible effect to species or habitat using at least 95% certainty
of no effects when considering all of the control measures
• quantitatively assess effects related to growth, survival, and reproduction
• consideration of incident information
• whether the control measures addressed any wide area effects
EPA evaluated the potential for off-field (near field and wide area) transport of dicamba by the
combination of spray drift and volatility, taking into account the mandatory control measures on
the product labeling. The Agency concludes the following related to spray drift:
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 •

•

The mandatory 310 feet in-field downwind spray drift setback to address spray drift
achieved a 95% probability that any effects would be limited to the treated field in
counties where required. Therefore, there are no discernible effects for listed species off
of the treated field.
If an approved hooded sprayer is used (optional, not mandatory on the labels), EPA
determined that the in-field downwind spray drift setback could be decreased from 310
feet to 240 feet in soybeans only. EPA determined this reduction in the setback does not
change the effects determinations.

EPA then considered the mandatory control measures that address volatile emissions. For the
effects determinations, EPA evaluated the combined volatile emissions control measures (VRAs,
application cut-off dates, and an in-field 57-ft omnidirectional volatile emissions application
buffer). The combination of these control measures results in a greater than 95% certainty that
dicamba exposures will remain within the confines of the field (i.e., the action area). Because
these combined control measures confine exposure to the treated field, EPA finds these measures
also address the potential for area wide exposures and loading to the downwind
atmosphere. Similarly, the prohibition against application after a certain date (depending on the
crop) reduces the timing of applications that would have occurred when temperature conditions
favor volatility, additionally reducing loading to the downwind atmosphere.
The requirement of an in-field 57-ft omnidirectional buffer also provides certainty that the action
area is confined to the treated field when considering pesticide runoff. This buffer in
combination with label instruction to prohibit application to saturated soils, or within 48 hours of
predicted rainfall events, further supports EPA’s conclusion that any discernible effects related to
the possibility of runoff are not reasonably expected to occur in the 287 counties where the 57-ft
buffer is required.
For these registration actions, EPA determined that 22 of 23 species and one critical habitat
overlap with the action area and the determination for these species and critical habitat is No
Effect. The remaining species (Eskimo Curlew) is “May Affect, Not Likely to Adversely
Affect.” Under the ESA section 7(a)(2) and its implementing regulations, EPA initiated informal
consultation with the U.S. Fish and Wildlife Service (USFWS). On October 22, 2020, EPA
received concurrence from FWS on our determination.
All listed other species and designated critical habitat within the 34 states of dicamba product use
are outside the action area. EPA concludes these listed species and designated critical habitat are
unaffected by this federal action, therefore the Agency does not need to make effect
determinations for all of the species outside the action area. For example, the Karner blue
butterfly (Lycaeides melissa samuelis) range occurs within some of the 34 states for use. This
species has an obligate relationship with wild lupines (Lupinus perennis) upon which the adults
lay eggs and the larvae develop. However, the species range does not overlap with the action
area, and an effects determination is not needed for a species outside the action area.

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