The list of nurseries registered with SAPPA are on the SAPPA website https://www.sappa.za.org/nurseries-kwekers/
It is the responsibility of the client to ensure that the trees or service meets their requirements, to assist with this evaluation SAPPA has drawn up a Minimum standard for nursery trees https://www.sappa.za.org/minimum-standards-for-nursery-trees/
All nurseries selling plant material should be registered with the Department of Agriculture, Forestry and Fisheries (DAFF) to obtain a nursery certificate and registration number.
Please note the SAPPA disclaimer for nursery trees:
It is not possible for the South African Pecan Nut Producers Association (SAPPA) to evaluate the quality of trees and services provided by nurseries that are associated members of SAPPA. It is the responsibility of the client to ensure that the trees or service meets their requirements.