Kaolin clay is an extremely fine form of clay used to create porcelain.
It is also a deadly weapon against many garden pests, especially those that attack apple trees. Apple maggots, apple aphids, two-spotted spider mites, leaf hoppers, pear psylla, oblique banded leaf hoppers, and codling moths are all susceptible to the effects of kaolin clay.
Kaolin clay powder creates a barrier between your fruit trees and common pests. Being edible, kaolin clay is nontoxic and can be used in organic gardens and orchards. There is no known danger to mammals or the environment posed by applying kaolin clay to your apple trees.
To use kaolin clay on your trees, it is very important to attain total coverage. Every spot that is not protected can be a point of entry for pests and disease. The brand name is Surround WP and it can be applied in liquid form using a sprayer. Applications should be performed at fruit set, generally early June, and sprayed periodically through mid-August. Surprisingly, kaolin clay, while it looks like a film that would block sunlight, actually increases net photosynthesis and helps keep the tree cooler!
To learn more about protecting your apple trees, read the UCANR report Apples: Organic Production Guide
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.