Proposed re-evaluation decision PRVD2026-01, prohexadione-calcium and its associated end-use products

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Pest Management Regulatory Agency
19 January 2026
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2026-1E-PDF (PDF version)

Summary

Table of contents

• Proposed re-evaluation decision for prohexadione-calcium and associated end use products
• Proposed label amendments
• Next steps
• Other information
• Additional scientific information

Proposed 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 regularly re-evaluated by Health Canada's Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet health and environmental safety standards and continue to have value. The re-evaluation considers data and information from pesticide manufacturers, incident reports and other regulatory agencies. Health Canada applies internationally accepted risk assessment methods, risk management approaches and policies to all re-evaluations.

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 of the full version of Proposed Re-evaluation Decision PRVD2026-01, Prohexadione-calcium and Its Associated End-use Products.

This document (PRVD2026-01) presents the proposed re-evaluation decision for prohexadione-calcium, including any proposed amendments (risk mitigation measures) to protect human health and the environment, as well as the science evaluation on which the proposed decision is based. All products containing prohexadione-calcium that are registered in Canada are subject to this proposed re-evaluation decision. PRVD2026-01 is subject to a 90-day public consultation period,^{Footnote 1} during which the public (including the pesticide manufacturers and stakeholders) may submit written comments and additional information to PMRA Publications. The final re-evaluation decision will be published after taking into consideration the comments received during the consultation period that are directly related to this proposed re-evaluation decision.

Health Canada, under the authority of the Pest Control Products Act, has conducted all evaluations considered necessary with respect to the health and environmental risks and value of prohexadione-calcium based on available scientific information in accordance with subsection 16(6) of the Pest Control Products Act. Health Canada is proposing for public consultation, pursuant to section 28 of the Pest Control Products Act, the continued registration of prohexadione-calcium and associated end-use products registered for sale and use in Canada under section 21 of the Pest Control Products Act.

Prohexadione-calcium has value as a plant growth regulator in providing a growth management solution. The potential occupational, bystander, residential, dietary, aggregate and environmental risks are considered to be acceptable when products containing prohexadione-calcium are used according to existing label directions. As a result of re-evaluation, no additional mitigation measures are proposed; however, updates to label statements as per current labelling standards are proposed (Appendix III of PRVD2026-01).

Proposed label amendments

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health, the environment and ensure the product has acceptable value which must be followed by law. The proposed label amendments including any revised/updated label statements, as a result of the re-evaluation of prohexadione-calcium, are summarized below. Refer to Appendix III of PRVD2026-01 for details.

Human health

• Update drift statement as per current standard.

Environment

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

Next steps

Upon publication of this proposed re-evaluation decision, the public, including the registrants and stakeholders are encouraged to submit comments during the 90-day public consultation period.

Health Canada will accept written comments on this proposal up to 90 days from the date of publication of PRVD2026-01. Comments on the proposed decision can be submitted during the consultation period to the PMRA through PMRA Publications, or the Public Engagement Portal (Public Engagement Portal forms – Consultation Comment). For more information or if you have questions, contact the PMRA's Pest Management Information Service.

Before making a re-evaluation decision on prohexadione-calcium under section 21 of the Pest Control Products Act, the comments received during the consultation period that are directly related to this proposed decision, such as comments directed to the science evaluation, will be taken into consideration in preparation of the final re-evaluation decision document. A science-based approach will be applied in making a final decision on prohexadione-calcium. In accordance with subsection 28(5) of the Pest Control Products Act, Health Canada will then publish a final re-evaluation decision document, which will include the decision,^{Footnote 2} the reasons for it, a summary of the comments received directly related to the proposed re-evaluation decision during the consultation period, and Health Canada's response to these comments.

Refer to Appendix I of PRVD2026-01 for details on specific products impacted by this proposed decision.

Other information

The relevant confidential test data on which the proposed decision is based are available for public inspection, upon application, in PMRA's Reading Room. For more information or if you have questions, please contact the PMRA's Pest Management Information Service.

Additional scientific information

No additional scientific data are being requested at this time.