This book is a product of the international VIDE (Virus Identification Data Exchange) project, which uses the DELTA (Description Language for Taxonomy) database system to collect diagnostic information on all plant viruses. Information on over 500 characters has been sought for each virus and stored in the VIDE database. Over two-thirds of these characters record the susceptibility, or otherwise, of a range of commonly used test plant species; the remainder represent the great range of other characters used for virus identification. Information on the known host range of each virus is also presented. The book, available as a two-volume set, covers approximately 1,000 viruses, which represents the entire database of plant viruses from around the world.