T-4-121 Phosphite/Phosphorus Acid Materials represented for use as fertilizers
This page is part of the Guidance Document Repository (GDR).
Looking for related documents?
Search for related documents in the Guidance Document Repository
This document provides interested parties with information regarding the CFIA's position on phosphite (phosphorous acid) materials represented for use as fertilizers.
Summary of CFIA Position
The CFIA has concluded an extensive review of the available scientific literature and has determined that phosphite materials, when sold on their own, do not meet the definition of a plant nutrient and thus a "fertilizer". Based on the documented fungicidal mode of action of these products they fall under the purview of the Pest Control Products Act which is administered by the Pest Management Regulatory Agency. When sold in combination with a plant available nutrient (such as Potassium, Calcium etc.) these products can be registered under the Fertilizers Act as fertilizer-pesticides providing they are approved by the PMRA for the pesticide use prior to registration under the Fertilizers Act.
Phosphite (Phosphorous Acid)
Phosphites are alkali metal salts of phosphorus acid and represent a reduced form of phosphate. When applied to plants, their primary mode of action is fungicidal. Representation and use of phosphite-containing products as fertilizers, and as sources of plant nutritional phosphorus, has been a subject of ongoing controversy. The preponderance of scientific evidence indicates that phosphites can be rapidly taken up by plant root systems but cannot be metabolized in the plant. As such, phosphites do not represent a source of metabolically-available phosphorus, and do not meet the definition of a "fertilizer" as prescribed by the Fertilizers Act.
Furthermore, there is significant evidence that phosphite treatments can have profound negative effects on plant growth and metabolism, by inducing phosphate starvation response in plants grown under phosphate limiting conditions in soil.
1. Fertilizers Act
All fertilizer and supplement products sold and imported into Canada are regulated under the authority of the Fertilizers Act, which is administered by the Canadian Food Inspection Agency (CFIA). Pursuant to the Act and Regulations, all regulated products must be safe (with respect to human, animal and plant health, as well as the environment), and properly labelled to ensure truthful representation of the product in the marketplace. Agricultural fertilizers, specialty fertilizers, fertilizer-pesticides and supplements are all controlled and regulated under the Fertilizers Act and Regulations.
A fertilizer is defined in the Fertilizers Act as any substance or mixture of substances, containing nitrogen, phosphorous, potassium or other plant food, manufactured, sold or represented for use as a plant nutrient.
A supplement is defined in the Fertilizers Act as any substance or mixture of substances, other than a fertilizer, that is manufactured, sold or represented for use in the improvement of the physical condition of soils or to aid plant growth or crop yields.
2. Pest Control Products Act
Phosphite products are known to have fungicidal properties and are commonly marketed for their pest control properties. When marketed as such in Canada, they meet the definition of a pest control product which falls under the purview of the Pest Control Products Act (PCPA), administered by the Pest Management Regulatory Agency (PMRA). A pest control product is defined in the PCPA as:
- (a) a product, an organism or a substance, including a product, an organism or a substance derived through biotechnology, that consists of its active ingredient, formulants and contaminants, and that is manufactured, represented, distributed or used as a means for directly or indirectly controlling, destroying, attracting or repelling a pest or for mitigating or preventing its injurious, noxious or troublesome effects;
- (b) an active ingredient that is used to manufacture anything described in paragraph (a); or
- (c) any other thing that is prescribed to be a pest control product.
3. Regulatory Jurisdiction
After careful consideration of the available scientific evidence, the CFIA has determined that phosphite materials, when sold on their own, do not meet the definition of a plant nutrient thus are not "fertilizers", they may also have negative effects on plant health when applied to crops under low-phosphorous conditions.
The results of discussions with the PMRA have determined that regulatory oversight for phosphite products will generally fall under the jurisdiction of the Pest Control Products Act. Once issued a registration and a Letter of No Objection by the PMRA, a phosphite product that is combined with a soluble plant available nutrient (such as K or Ca) may be registered under the Fertilizers Act and Regulations as fertilizer-pesticide.
Proponents of phosphite materials are directed to contact the PMRA to seek registration and/or approval. Once the phosphite is registered under the PCPA for use in combination with a fertilizer, an application to register the blended material as a fertilizer-pesticide under the FzA may be submitted to the CFIA. To be granted registration under the FzA, the proponent must demonstrate that the final product meets CFIA safety and labelling – including all applicable pesticide safety precautions prescribed by the PMRA on the final fertilizer-pesticide label. In addition, the label must contain a precautionary statement cautioning against application of the product to phosphorous-limited soils due to phytotoxicity effects.
Further Guidance on Regulatory Requirements for Fertilizer-Pesticides
Additional details related to the regulation of Fertilizer-Pesticides under the Fertilizers Act can be found in
T-4-102: Requirements for Registration or exemption for fertilizer-pesticides.
Should you have any questions regarding the CFIA's position on phosphorous acid materials (phosphites) please address your question to the:
Fertilizer Safety Section
c/o Pre-market Application Submissions Office (PASO)
Canadian Food Inspection Agency
59 Camelot Drive
Ottawa, ON K1A 0Y9
For questions regarding the PMRA's regulation of pest control products, please contact the PMRA directly:
Address Locator 6606D2
Website: Pest Management Information Service
Toll free: 1-800-267-6315
Teletypewriter: 1-800-465-7735 (Service Canada)
- Date modified: