Surround (the branded kaolin clay) was originally being marketed as an insect suppressant but pivoted when another sun shield product started going through the registration process. We have used it and I agree that it will reduce foliar nutrient uptake, but I don’t use it anymore because I don’t think it reflects the correct wavelengths of light. It doesn’t defuse the light either. I’d worry about it getting on any food product and not washing off. In our area it is only used post harvest or on nut crops.