A harmless clay-based solution, sprayed on apple trees, can protect the fruit from some diseases and insect pests. Andrew Thomas, a research associate at the University of Missouri Southwest Center near Mt. Vernon, has tested a spray made of kaolin, a nontoxic clay that is so safe it has been approved for human consumption. "If you've ingested Kaopectate, you've eaten kaolin," he points out.
A kaolin-based spray, Surround, was released in 2000 and successfully used to treat pear ...