The diagnostic keys for apple, cherry, and peach diseases were developed to aid field personnel in the identification of diseases that are common to the Northeastern region of the United States. The keys are arranged to guide a user through a series of logically arranged statements describing symptoms and signs of fruit tree disorders. By selecting from a series of numbered statements, those which most closely describe observations made in the field, the user should beableto narrowthe possibilitiestoonly oneor a couple of probable diseases.