Consultation on dicamba and its associated end-use products, Proposed Special Review Decision PSRD2025-01 (revised)

Purpose of this consultation

Health Canada is consulting the public and seeking your feedback on the proposed special review decision for dicamba and its associated end-use products.

The consultation focuses specifically on the aspect of concern that initiated this special review: the potential risk to non-target terrestrial plants from the use of commercial dicamba products.

Following the thorough environmental risk assessment for dicamba and a review of incident reports, Health Canada is proposing these changes to reduce the risk to non-target terrestrial plants:

• cancel one use
• update spray drift buffer zones
• add risk mitigation measures for volatility

You can find more details in the proposed special review decision document, including the scientific rationale and proposed changes.

On this page

• What is dicamba
• Key impacts and who may be affected
  • Registrants
  • Soybean and field corn growers and government partners in the agriculture sector
  • Members of the public
• Why this special review is occurring
  • Understanding how dicamba moves through the environment
  • Incident reports for damage to nearby plants
• How to get involved
• Related information
• Reporting to the people of Canada

What is dicamba

Dicamba is an herbicide used to control broadleaf weeds, particularly those resistant to other herbicides. It moves through the entire plant after being absorbed by the leaves, roots, or stems.

Dicamba-tolerant (DT) crops, like DT soybean and DT field corn, can withstand the effects of dicamba. This allows growers to apply dicamba to control weeds without damaging the crop itself.

In Canada, dicamba is registered for use on:

• dicamba-tolerant soybean
• both dicamba-tolerant and non-dicamba-tolerant field corn,
• other cereal crops that are not dicamba-tolerant
• lowbush blueberries
• grasses, turf, and lawns
• fallow and stubble fields
• non-agricultural areas such as roadsides, hydro corridors, pipelines, railways, airports, military bases, and wasteland

Dicamba and its associated end-use products are currently under re-evaluation where a full review will be completed, including a review of all products (including domestic products).

Key impacts and who may be affected

The proposed special review decision for dicamba outlines key impacts that may affect the following stakeholders.

Registrants

• Removal of “over-the-top” (OTT) applications to DT soybeans after the crop starts growing (post-emergence). Currently, dicamba products can be applied once before planting or emergence, and up to two more times post-emergence.
• Cancellation of its use during DT soybean seed production.
• Best management practice statement about temperature to avoid application when temperatures exceed 25 C, as warmer temperatures can cause dicamba to volatilize and move off-site.

Soybean and field corn growers and government partners in the agriculture sector

• Removal of “over-the-top” (OTT) applications to DT soybeans after the crop starts growing (post-emergence). Currently, dicamba products can be applied once before planting or emergence, and up to two more times post-emergence.
• Cancellation of its use during DT soybean seed production.
• Best management practice statement about temperature to avoid application when temperatures exceed 25 C, as warmer temperatures can cause dicamba to volatilize and move off-site.
• Lower the maximum plant height for application on DT field corn crop from 76 cm to 50 cm. This will help reduce the chance of pesticide drift to nearby plants or areas and align with the current application height limit for non-DT field corn.
• Update the size of spray buffer zones for crop and non-crop areas, ranging from 1 to 115 metres for field sprayers and from 45 to 800 metres for aerial application.

Members of the public

While members of the public may not be directly affected by this proposed special review decision, the following updates provide context for the decision.

• A preliminary review of incident reports involving damage to plants outside the application area triggered this special review
• Marginal changes to spray buffer zones and applications limits are proposed to protect plants in adjacent fields and areas

Health Canada reviewed the latest information provided to the Pesticide Incident Reporting Program to update the non-target terrestrial plants risk assessment, along with information considered for the previous re-evaluation of dicamba and decisions from the United States and Australia. No additional information was identified from the public literature. Results from the review show that with the implementation of updated risk mitigation measures, dicamba continues to meet Health Canada’s requirements for the protection of the environment as it relates to the aspect of concern.  

Why this special review is occurring

A special review may be initiated at any time if there are reasonable grounds to believe that the health, environment or value requirements of a pesticide are no longer met. A special review may be triggered by new information provided through various sources such as the Incident Reporting Program, other government partners, members of the public, or when an Organisation for Economic Co-operation and Development member country prohibits all uses of a pesticide for health or environmental reasons.  

Health Canada initiated the special review based on a preliminary analysis of environmental incident reports and a new non-target plant toxicity study submitted through the Incident Reporting Program. This special review focuses on the potential risk of dicamba to non-target terrestrial plants.

New data indicated a greater risk to non-target terrestrial plants, prompting a review of this risk from all outdoor uses of dicamba.

To evaluate the issue, Health Canada reviewed the information that initiated the special review, along with other relevant information currently available. This included information from international regulatory authorities like the United States Environmental Protection Agency and Australian Pesticides and Veterinary Medicines Authority.

Understanding how dicamba moves through the environment

Dicamba has the potential to cause damage to non-target terrestrial plants by moving from the site where it was applied to other areas through spray drift and volatilization:

• Spray drift occurs during pesticide application if the droplets emitted by the spray equipment are carried downwind from the site of application.
• Volatilization happens if a pesticide evaporates from the sprayed material during application or from surfaces such as soil or plants after application. The volatilized pesticide can then be transported by the wind.

Health Canada’s risk assessment during this special review found that dicamba has the potential to volatilize and move off-site throughout the entire growing season in Canada.

Temperature and pH can strongly affect how much dicamba volatilizes and moves off-site. A review of past environmental incident reports in Canada and the United States suggests that the current measures to mitigate dicamba volatilization through temperature and pH have not been fully effective for use on DT crops.

For more information on mitigating pesticide drift: Drift Mitigation - Canada.ca.

Incident reports for damage to nearby plants

Health Canada looked at incident data trends from 2007, when the Incident Reporting Program was established, and onwards. The first product registration for use on dicamba-tolerant cops was registered in 2013. The first reported environmental incident involving dicamba with products with uses on DT crops that caused damage to non-target terrestrial plants happened in 2015.

In the past ten years, there were 101 reported cases involving damage to terrestrial plants, 89% of which involved just five commercial products with registered uses in DT crops.

How to get involved

This consultation is open for comment from 17 September 2025 to 16 December 2025 (90 calendar days). 

To comment on PSRD2025-01: 

• Step 1: Open "View a summary of the proposed decision" below to access the document. 
• Step 2: Submit comments to the Pest Management Regulatory Agency Publications Section. 

Please be sure to include the title of the consultation document on which you are commenting. Interested parties are encouraged to provide comments by 16 December 2025. 

Health Canada will consider comments directly related to the assessment of the aspect of concern received up to 90 days from the date of publication of this document (by 16 December 2025) before making a final decision on the proposed special review decision for dicamba.

View a summary of the proposed decision

If you would like to request additional information on the supporting scientific documents for this proposed registration decision, contact the Pest Management Information Service. Include the following information in the request:

• Active ingredient: dicamba
• Published document number: PSRD2025-01
• Submission numbers: 2019-6324, 2023-6495, 2023-6497, 2023-6498, 2024-0552, 2024-0553, 2024-0554, 2024-0555, 2024-0556, 2024-0557, 2024-0558

Related information

• Approach to special reviews of pesticides: PMRA guidance document
• Pesticide Incident Reporting Program
• 2008 Re-evaluation Decision of Dicamba (RVD2008-28)

Reporting to the people of Canada

Through the publication of a Special Review Decision document, Health Canada will communicate the final decision on the Pesticides and Pest Management Decisions and Updates page. This document will include the decision, the reasons for it, a summary of comments received on the proposed special review decision and Health Canada’s response to these comments.

If you have any questions, contact the Pest Management Information Service.

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