Re-evaluation Decision RVD2026-06, Prohexadione-calcium and its associated end-use products

Health Canada
Healthy Environments and Consumer Safety Branch
Pesticides Regulatory Directorate
16 October 2026
ISSN: 1925-1025 (PDF version)
Catalogue number: H113-28/2026-6E-PDF (PDF version)

Summary

Table of contents

• Re-evaluation decision for prohexadione-calcium and associated end-use products
• Re-evaluation decision for prohexadione-calcium
• Risk mitigation measures
• Implementation of the re-evaluation decision
• Amendment timeframe
• Continuous oversight
• Proportional effort
• Next steps
• Other Information
• Appendix I Registered products containing prohexadione-calcium in Canada1

Re-evaluation decision for prohexadione-calcium and associated end-use products

Under the authority of the Pest Control Products Act, all registered pesticides must be re-evaluated by Health Canada to ensure that they meet current health and environmental standards and have value. The re-evaluation considers data and information from pesticide manufacturers, incident reports and other regulatory agencies, as well as comments directly related to the proposed re-evaluation decision, such as comments directed to the science evaluation, received during public consultations. Health Canada applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Prohexadione-calcium is a plant growth regulator which inhibits the biosynthesis of gibberellins thereby reducing vegetative growth, allowing for a balance between canopy development and fruit production for the registered use on apples and cherries (sweet and tart), and for suppression of runners in strawberries. In addition, prohexadione-calcium is registered for growth management of turfgrass species (bentgrass, annual and perennial Poa annua, Kentucky bluegrass, perennial ryegrass, tall fescue and fine fescue) growing on golf courses, sod farms, sports fields, municipal sites and cemeteries. Currently registered products containing prohexadione-calcium can be found in the Pesticide Product Information Database and in Appendix I or in the full version of Re-evaluation Decision RVD2026-06, Prohexadione-calcium and its associated end-use products. The Proposed Re-evaluation Decision PRVD2026-01, Prohexadione-calcium and its associated end-use products^{Footnote 1} containing the evaluation of prohexadione-calcium and proposed decision, underwent a 90 day consultation period ending on 19 April 2026. PRVD2026-01 proposed updates to the spray drift statement and buffer zone tables.

Written comments were received during the public consultation period conducted in accordance with section 28 of the Pest Control Products Act. However, they did not relate to the health, environmental or value assessments in the proposed re-evaluation decision, PRVD2026-01, Proposed Re-evaluation Decision, Prohexadione-calcium and its associated end-use products. Therefore, this decision is consistent with the proposed re-evaluation decision as described in PRVD2026-01.

A reference list of information used as the basis for the proposed re-evaluation decision is included in PRVD2026-01; no further information was used in the final re-evaluation decision. Therefore, the complete reference list of all information used in this final re-evaluation decision is set out in PRVD2026-01.

This document (RVD2026-06) presents the final re-evaluation decision^{Footnote 2} for the re-evaluation of prohexadione-calcium, including the required amendments (risk mitigation measures) to protect human health and the environment, as well as label amendments required to bring labels to current standards. All products containing prohexadione-calcium that are registered in Canada are subject to this re-evaluation decision.

Re-evaluation decision for prohexadione-calcium

Health Canada has completed the re-evaluation of prohexadione-calcium. Under the authority of the Pest Control Products Act, Health Canada has completed all required evaluations and consultations and has determined that the registration of products containing prohexadione-calcium is required to be amended, in accordance with paragraph 21(2)(a) of the Pest Control Products Act. An evaluation of available scientific information respecting the health and environmental risks and value of prohexadione-calcium found that all uses of prohexadione-calcium products meet current standards for protection of human health and the environment and have acceptable value when used according to the amended conditions of registration. Label amendments, as summarized below and listed in Appendix II of RVD2026-06, are required.

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 required amendments, including any revised/updated label statements and/or mitigation measures, as a result of the re-evaluation of prohexadione-calcium, are summarized below. Refer to Appendix II of RVD2026-06 for details.

Human health

Label improvements to meet current standards:

• Update drift statement as per current standard.

Environment

Label improvements to meet current standards:

• Update spray buffer zone table for the turf uses for clarity.

Implementation of the re-evaluation decision

Regulatory Directive DIR2018-01, Policy on Cancellations and Amendments Following Re-evaluation and Special Reviewprovides information and general timelines regarding the implementation of post-market decisions, (for example, up to 24-month timeline for label amendments and up to 36-month phase-out timeline for cancelled registrations), and Information Note: Update on implementation of post-market decisions provides additional information on phase-out measures for post-market decisions that include cancellations. The post-market decision considers potential health and environmental risks regarding the use of the pest control product, and its value, when establishing the implementation timelines.

Amendment timeframe

The implementation timeline of 24 months for the required amendments (mitigation measures and label updates) for pest control products containing prohexadione-calcium is considered acceptable. These required amendments must be implemented within 24 months after the publication date of this decision document.

Refer to Appendix I for details on specific products impacted by this decision.

Continuous oversight

The PRD's policy on continuous oversight of pesticides and the associated information note describe the process by which Health Canada monitors published scientific literature for active ingredients registered in Canada, and the criteria used to determine which active ingredients will be monitored when a final regulatory decision is made. The criteria in the information note have been met, therefore, scientific literature and regulatory information will be monitored as part of continuous oversight for this active ingredient.

Proportional effort

Active ingredients registered in Canada are categorized based on criteria in Health Canada's Policy on Proportional Effort. The categorization is used to inform Health Canada's allocation of resources related to pesticide reviews in alignment with the required level of regulatory effort. Prohexadione-calcium is categorized as lower Proportional Effort based on the general criterion, health criteria, and environmental criteria. The Proportional Effort categorization will be used to inform the potential scope of future reviews.

Next steps

To comply with this decision, the required amendments (mitigation measures and label updates) must be implemented on all product labels no later than 24 months after the publication date of RVD2026-06. Accordingly, both registrants and retailers will have up to 24 months from the date of this decision document to transition to selling the product with the newly amended labels. Similarly, users will also have the same 24-month period from the date of RVD2026-06 to transition to using the newly amended labels, which will be available on the Public Registry.

Refer to Appendix I for details on specific products impacted by this decision.

Other Information

The relevant confidential test data on which the decision is based (as referenced in PRVD2026-01) are available for public inspection, upon application, in Pesticides Regulatory Directorate's Reading Room. For more information or if you have questions, contact Health Canada's Pesticides Information Service.

Any person may file a notice of objection^{Footnote 3}, which must be based on scientific grounds, regarding this decision on prohexadione-calcium and its associated end-use products within 60 days from the date of publication of this Re-evaluation Decision through the Public Engagement Portal (Public Engagement Forms - Notice of Objection). The request for reconsideration must include the Notice of Objection form, the scientific explanation of the objection and the supporting scientific evidence in possession of the requestor that wouldn't already be in Health Canada's possession or cite specific Health Canada documentation they wish to rely on as supporting evidence (for example, scientific reports) in the form of electronic copies of cited references. Each of the references provided or cited must be clearly associated with the objection it supports. Failure to provide a complete package may result in the Notice of Objection being considered ineligible for further consideration by Health Canada. 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 the Canada.ca website or contact Health Canada's Pesticides Information Service.

Appendix I Registered products containing prohexadione-calcium in Canada