The whole of NZ pastoral areas had intensive aerial spraying.
Controlling Gorse and reclaiming pastoral lands back from the wide spread of gorse.
NZ agricultural board will have specific records hopefully of the mass application NZ did to its prime industry lands.
Basically none of NZ was spray free. It's a given if it's pastoral or agricultural it's been subject to 2,4,5t and/or 2,4d in aerial spray and or fertilizers soaked in it