The CanadaGAP requirements state that “The applicator follows prevailing legislation (e.g., provincial regulations) AND has completed formal training (e.g., online course, self-study course with materials and successful completion of exam, etc.).”
Provincial requirements vary, and there is a CanadaGAP FAQ about these requirements (including a table of references). Knowing if an agricultural chemical application certificate is still valid will depend on the province and their requirements. For example, currently in BC, certificates from other provinces are not valid in BC, but there is a reciprocity exam that can be completed for certain categories of certificates. The requirements vary from province to province so operations must find out the requirements in their location.