Can kaolin clay sprays reduce insect damage to apple fruit?

Yes. Kaolin clay (formulated commercially as Surround WP®) has been shown to be effective against several orchard pests, including apple maggot, white apple leafhopper, and pear psylla. It generally gives at least fair control of plum curculio and several species of fruit pest caterpillars (codling moth, oriental fruit moth, tufted apple bud moth, lesser appleworm). However, university trials also show that heavy use is harmful to beneficial species, and can lead to a flare up of European red mites or …