By Lisa M. Campbell, James V. Aidala, and Lisa R. Burchi
On June 7, 2016, the U.S. Environmental Protection Agency (EPA) announced that it was making two draft Pesticide Registration Notices (PR Notices) available for public comment: (1) PR Notice 2016-X: Draft Guidance for Pesticide Registrants on Pesticide Resistance Management Labeling; and (2) PR Notice 2016-XX: Draft Guidance for Herbicide Resistance Management Labeling, Education, Training, and Stewardship. In its news release, EPA states that it has started a “more widespread effort aimed at combating and slowing the development of pesticide resistance,” in an effort to “address the growing issue of resistance and preserve the useful life of pesticides.”
Draft PR Notice 2016-X
Draft PR Notice 2016-X, which revises and updates PR Notice 2001-5, applies to all conventional agricultural pesticides (i.e., herbicides, fungicides, bactericides, insecticides and acaricides). The focus of the updates in PR Notice 2016-X is on pesticide labels and improving information about how pesticide users can minimize and manage pest resistance.
Specifically, EPA is proposing that specific resistance-management statements be included with the Directions for Use section under the heading “Resistance Management Recommendations.” EPA states that the proposed labeling statements “focus on the mitigation of pest resistance and should be used where applicable based on the availability of other pesticides and production practices specific to that crop.” As one example, EPA recommends the following general resistance management labeling statements for insecticide/acaricide products containing only a single active ingredient or multiple active ingredients that are from the same Mode of Action (MOA) group:
- For resistance management, (name of product) contains a Group (mode of action group number) insecticide (or acaricide). Any (insect/mite) population may contain individuals naturally resistant to (name of product) and other Group (mode of action group number) insecticides/acaricides. The resistant individuals may dominate the insect/mite population if this group of insecticides/acaricides are used repeatedly in the same fields.
Since the recommended resistance-management statements depend on an active ingredient’s MOA, PR Notice 2016-X also addresses MOA grouping and identification symbols for agricultural uses of herbicides, fungicides/bactericides, and insecticides/acaricides. The pesticide groupings are provided by the Weed Science Society of America (WSSA), the Herbicide Resistance Action Committee (HRAC), the Fungicide Resistance Action Committee (FRAC) and the Insecticide Resistance Action Committee (IRAC). The MOA groups, and the identifier numbers and/or letters (i.e., symbols or codes) for herbicides, fungicides/bactericides and insecticides/acaricides may be accessed through the websites of the different Resistance Action Committees. For example, for insecticides, IRAC uses a combination of numbers and letters to identify various MOA groups. EPA recommends that the IRAC MOA identifier codes be used for designating insecticide MOA grouping information on labels for pesticides containing insecticides. The IRAC MOA list and identifier codes can be found online.
While current PR Notice 2001-5 contains similar guidance in terms of MOA groupings and general pesticide-resistance statements, the Draft PR Notice 2016-X provides: (1) additional guidance, and recommended format, for resistance management statements or information to place on labels; (2) includes references to external technical resources for guidance on resistance management (e.g., professional scientific societies, resistance action committees for different types of pesticides); and (3) updates the instructions on how to submit changes to existing labels to enhance resistance management language. In addition, while PR Notice 2001-5 states that “implementation of this program is purely voluntary by the pesticide industry,” the language in Draft PR Notice 2016-X is arguably stronger, with EPA “encouraging” registrants to add the appropriate resistance-management statements through notification, amendment, or as part of an application for a new product.
Draft PR Notice 2016-XX
Draft PR Notice 2016-XX, which only applies to herbicides, is intended to provide guidance on labeling, education, training, and stewardship for herbicides undergoing registration review or registration (i.e., new herbicide actives, new uses proposed for use on herbicide-resistant crops, or other case-specific registration actions). EPA states it is focusing on the holistic guidance for herbicides first because:
- Herbicides are the most widely used agricultural chemicals;
- No new herbicide mechanism of action has been developed in the last 30 years; and
- Herbicide-resistant weeds are rapidly increasing. In the future, the Agency plans to evaluate other types of pesticides (e.g., fungicides, bactericides, insecticides, and acaricides) to determine whether and what guidance may be appropriate for these types of pesticides.
Under guidance described in PR Notice 2016-XX, EPA proposes to divide 28 herbicide Mechanisms of Actions into three categories of concern (low, moderate, high) based on the risk of developing herbicide-resistant weeds. Appendix I to PR Notice 2016-XX provides three tables with herbicide Mechanisms of Actions of “Low Concern,” “Moderate Concern,” and “High Concern” for herbicide resistance. EPA states its intent to make these tables available on its website, noting that the tables would need to be “checked periodically to determine if there are changes to the groupings or level of concern categories.” Appendix II to PR Notice 2016-XX sets forth the following eleven elements that are focused on labeling, education, training, and stewardship strategies:
- Element 1. List Mechanism of Action Group Number on label.
- Element 2. List seasonal and annual maximum number of applications and amounts.
- Element 3. Provide Resistance Management language from PR Notice 2016-X, and/or Best Management Practices language from WSSA and HRAC, and/or HRAC proposed guidelines for herbicide labels. Note that Best Management Practices (BMP) should be appropriate to crop and production system.
- Element 4. Instruction to user to scout before and after application.
- Element 5. Provide definition of Likely Resistance.
- Element 6. Instruction to user to report lack of performance to registrant or their representative.
- Element 7. List confirmed resistant weeds in a separate table and list recommended rates for these weeds with the table.
- Element 8. Registrant report new cases of likely and confirmed resistance to EPA and users yearly. This is in addition to any adverse effects reporting.
- Element 9. Provide growers with:
- Resistance Management Plan;
- Remedial Action Plan (to control resistant weeds this season or next season);
- Educational materials on resistance management; and
- Plans should be locally developed and easily modified. EPA recommends that registrants work with Extension, Consultants, Crop Groups, HRAC, and the U.S. Department of Agricultute (USDA).
- Element 10. For combination products with multiple Mechanisms of Action, list which herbicide is controlling which weed (a three-way mixture may only have one effective Mechanism of Action for some problem weeds). List minimum recommended rate if resistance is suspected.
- Element 11. Any additional specific requirements (e.g., mandatory crop rotation, unique agronomic aspects, additional training, time limited registration, etc.).
Elements 1 through 4 are proposed for Mechanisms of Actions of Low Concern, elements 1 through 8 are proposed for Mechanisms of Actions of Moderate Concern, and elements 1 through 11 are proposed for Mechanisms of Actions of High Concern.
The PR Notices are available on www.regulations.gov under Docket Numbers EPA-HQ-OPP-2016-0242 for PR Notice 2016-X; and EPA-HQ-OPP-2016-0226 for PR Notice 2016-XX. Comments are due by August 2, 2016.
With regard to PR Notice 2016-XX, EPA states that while comments are welcome on all aspects of this Notice, EPA is especially interested in comments on the following: (1) the approach, elements and categorization used to address herbicide resistance; (2) limiting the application of these measures during registration review to new herbicide active ingredients, new uses of herbicides proposed for use on herbicide-resistant crops, and other case-specific registration actions; (3) other effective measures to inform the stakeholder community of the occurrence of likely resistance; and (4) other useful strategies that, when implemented, would slow the development of herbicide resistance and prolong the useful life of herbicides.
More information on pesticide resistance management is available on EPA’s website.
Avoiding the onset of resistance to any pesticide product is a widely shared goal of users and registrants of the pesticide to maintain the effectiveness and profitability of the product. There is controversy, however, when EPA suggests specific instructions to the user community, since pesticide applications are site and situation specific, making general “one size fits all” approaches, even “flexible” ones, suspect among much of the user community. When the instructions involve label requirements, which are enforceable, concerns about flexibility and the need to adapt to local conditions increase.
Resistance management has been a stated goal of EPA for some time; here EPA seems to argue it is of the utmost importance to preserve useful pest control tools since it is better to have more “tools in the toolbox.” Yet, when EPA seeks to restrict a product or class of products and users and registrants cite the need for that product for resistance management, few benefits seem to be associated with resistance management in such cases. Overall, there is also suspicion that EPA’s concerns regarding herbicide resistance masks a political response to critics of the widespread adoption of herbicide-resistant genetically engineered crops -- since the high value of resistance management gains little value when EPA attempts to restrict other products. An example is EPA’s approach to organophosphate insecticides, where EPA is currently seeking to eliminate many uses that otherwise are viewed as important for insecticide resistance management.
Having EPA attempt to address resistance management via label instructions will be controversial, notwithstanding broad consensus that avoiding resistance is a shared goal. So, the likely debate will focus less on the goal, and more on the means of achieving the goal, as this issue moves forward.