Re-evaluation Decision RVD2018-08, Diflufenzopyr-sodium and Its Associated End-use Products

Pest Management Regulatory Agency
25 April 2018
ISSN: 1925-1025 (PDF version)
Catalogue number: H113-28/2018-8E-PDF (PDF version)

(PDF Version - 82 K)

Re-evaluation Decision

Under the authority of the Pest Control Products Act, all registered pesticides must be regularly re-evaluated by Health Canada's Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet current health and environmental safety standards and continue to have value. The re- evaluation considers data and information from pesticide manufacturers, published scientific reports and other regulatory agencies. The PMRA applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Diflufenzopyr-sodium is a post-emergent herbicide for use on various crops such as field corn, non-cropland, fallow cropland and pasture. Currently registered products containing diflufenzopyr-sodium are listed in Appendix II.

This document presents the final regulatory decisionFootnote1 for the re-evaluation of diflufenzopyr-sodium including the required risk mitigation measures to protect human health and the environment. All pest control products containing diflufenzopyr-sodium that are registered in Canada are subject to this re-evaluation decision. This re-evaluation decision has gone through a 90-day consultation period as Proposed Re-evaluation Decision PRVD2017-04, Diflufenzopyr-sodium.

The comments received during the consultation period are summarized in Appendix I along with the responses by the PMRA. The comments received did not result in changes to human health and environmental risk assessments. The required label amendments are included in Appendix III. A reference list of data used as the basis for the proposed re-evaluation decision is included in PRVD2017-04.

Regulatory Decision for Diflufenzopyr-sodium

The PMRA has completed the re-evaluation of diflufenzopyr-sodium. Under the authority of the Pest Control Products Act, the PMRA is granting continued registration of products containing diflufenzopyr-sodium for sale and use in Canada. An evaluation of available scientific information found that the pesticide use of diflufenzopyr-sodium products does not present unacceptable risks to human health or the environment when used according to the conditions of registration, including amended label directions. Label amendments, as summarized below and listed in Appendix III, are required for all commercial class end-use products containing diflufenzopyr-sodium. No additional data are requested at this time.

Risk Mitigation Measures

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment and must be followed by law. The following measures are required based on the current labeling standard (Appendix III).

Human Health

  • Precautionary label statement to minimize bystander exposure from spray drift.


  • Buffer zone and label statements to protect non-target organisms.
  • Environmental hazard label statements.

Next Steps

To comply with this decision, the required mitigation measures must be implemented on all products labels sold by registrants no later than 24 months after the publication date of this decision document. Appendix II lists the pesticide products containing diflufenzopyr-sodium that are registered under the authority of the Pest Control Products Act.

Other Information

Any person may file a notice of objectionFootnote2 regarding this decision on diflufenzopyr-sodium within 60 days from the date of publication of this Re-evaluation Decision. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the Pesticides and Pest Management portion of (Request a Reconsideration of Decision) or contact the PMRA's Pest Management Information Service.

Appendix I - Comments and Responses

In response to the consultation of the diflufenzopyr-sodium proposed re-evaluation decision (PRVD2017-04), the following comments were received:

  1. Comment regarding use description and restricted entry interval.

    The PRVD2017-04 indicates that diflufenzopyr-sodium can be applied one time per season. For the Chemfallow and Post-harvest use pattern, diflufenzopyr-sodium can be applied up to two applications in a season not exceeding a maximum seasonal application rate of 57 g a.i./ha.

    The PRVD2017-04 indicates that not all labels include a restricted-entry interval (REI); and therefore, an update to labels to indicate a minimum restricted-entry interval of 12 hours is proposed. However, the labels for all registered end-use products already do contain a restricted entry interval statement.

    PMRA Response

    The PMRA agrees with these comments. No amendments to REI requirements included on the current labels are required.

  2. Comment concerning registered diflufenzopyr-sodium products

    The registration number for Distinct Herbicide is 25811 instead of 25881 as listed in the PRVD 2017-04. As well, the product Distinct WDG Herbicide, Registration Number 26406, should be included in the list of registered products.

    PMRA Response

    The revised list of registered products is included in Appendix II.

Appendix II - Registered Diflufenzopyr-sodium Products as of 19 January 2018

Table 1 - Registered Diflufenzopyr-sodium Products as of 19 January 2018
Registration Number Marketing Type Registrant Name Product Name Formulation type Guarantee
29004 Technical Grade Active Ingredient BASF Canada Inc. Sodium Diflufenzopyr Technical Herbicide Dust or powder Diflufenzopyr- sodium: 86.3%
26143 Manufacturing Concentrate BASF Canada Inc. Distinct Herbicide Manufacturing Concentrate Wettable Granule Diflufenzopyr-
sodium: 20%

Dicamba: 50%
25811 Commercial BASF Canada Inc. Distinct Herbicide

Wettable Granule

sodium: 20%

Dicamba: 50%
26406 Commercial BASF Canada Inc. Distinct WDG Herbicide

Wettable Granule

sodium: 20%

Dicamba 50%
30065 Commercial BASF Canada Inc. Overdrive Herbicide

Wettable Granule

sodium: 20%

Dicamba: 50%

Appendix III - Label Amendments for Commercial Class End-use Products Containing Diflufenzopyr-sodium

The label amendments presented below do not include all label requirements for individual end-use products, such as first aid statements, disposal statements, precautionary statements and supplementary protective equipment. Information on labels of currently registered products should not be removed unless it contradicts the label statements provided below.

A submission to request label revisions will be required within 90 days of finalization of the re-evaluation decision.

  1. Under PRECAUTIONS, the following statements must be added or replace the relevant sentence:

    "DO not use in residential areas. Residential areas are defined as any use site where bystanders, including children, could be exposed during or after application. This includes homes, schools, parks, playgrounds, playing fields, public buildings, or any other area where the general public, including children, could be exposed."

    "Apply only when the potential for drift to areas of human habitation or areas of human activity such as houses, cottages, schools and recreational areas is minimal. Take into consideration wind speed, wind direction, temperature inversions, application equipment and sprayer settings."

  2. The following statements must be included in a section entitled ENVIRONMENTAL HAZARDS.

    "TOXIC to non-target terrestrial plants. Observe buffer zones specified under DIRECTIONS FOR USE."

    "To reduce runoff from treated areas into aquatic habitats, avoid application to areas with a moderate to steep slope, compacted soil, or clay."

    "Avoid application when heavy rain is forecast."

    "Contamination of aquatic areas as a result of runoff may be reduced by including a vegetative strip between the treated area and the edge of the water body."

  3. The following statements must be included in a section entitled DIRECTIONS FOR USE.

    "Field sprayer application: DO NOT apply during periods of dead calm. Avoid application of this product when winds are gusty. DO NOT apply with spray droplets smaller than the American Society of Agricultural Engineers (ASAE) medium classification. Boom height must be 60 cm or less above the crop or ground."

    "DO NOT apply by air."

    "As this product is not registered for the control of pests in aquatic systems, DO NOT use to control aquatic pests."

    "DO NOT contaminate irrigation or drinking water supplies or aquatic habitats by cleaning of equipment or disposal of wastes."

    Buffer Zones:

    Use of the following spray methods or equipment DO NOT require a buffer zone: hand- held or backpack sprayer and spot treatment.

    The buffer zones specified in the table below are required between the point of direct application and the closest downwind edge of sensitive terrestrial habitats (such as grasslands, forested areas, shelter belts, woodlots, hedgerows, riparian areas and shrublands).

Table 2 - Buffer Zones Required
Method of application Crop Buffer Zones (metres) Required for the Protection of Terrestrial habitat:
Field Sprayer Field corn, non-cropland, pasture, rangeland 1

For tank mixes, consult the labels of the tank-mix partners and observe the largest (most restrictive) buffer zone of the products involved in the tank mixture and apply using the coarsest spray (ASAE) category indicated on the labels for those tank mix partners."

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