Proficiency testing  and PT provider in pesticide formulation

You asked

I need you help regarding Proficiency testing and PT provider in pesticide formulation

I cannot recommend any providers as it depends on your scope and area. Have a look at EPTIS at https://www.eptis.org for posisble providers. This is an International database of Proficiency Testing (PT) schemes.

You also asked

I need your help with regard to PT testing as we couldn't find any in our scope .is there any alternative?"

The policy document ILAC-P9:06/2014 ILAC Policy for Participation in Proficiency Testing Activities is applicable to your situation. It is available at https://ilac.org/publications-and-resources/ilac-policy-series/

What I suggest you do is contact your accreditation body as well, as they will need to approve the alternative which typically would involve a bilateral study between yourself and one other laboratory or the use of certified reference materials for your own study.