This agriculture extension service publication from Pennsylvania State University consists of four sections on plant disease recognition and control. The titles of these four sections are: (1) Some Important Diseases of Tree Fruits; (2) Diseases of Vegetable Crops; (3) Diseases of Crops; and (4) Diseases of Tree Nuts. The first section discusses the various disease causing organisms and gives hosts, symptoms, disease cycle, and control information for the tree fruit diseases which are alphabetized for easy reference. The second section specifically discusses the diseases of beans, crucifers, cucurbits, peas, potatoes, sweet corn, and tomatoes. The third section examines six common diseases of grapes in Pennsylvania. The final section describes Walnut Anthracnose, Walnut Blight, and Filbert Bacterial Blight. (MR)