The first edition of this book was published in 1986 as a reference work for bacteriologists and plant pathologists. The second edition represents an update encompassing the full range of information on nomenclature, synonymy, characteristics, type cultures, host ranges, symptoms and geographical distribution for known plant pathogenic bacteria. In recent years the taxonomy of these bacteria has been revised, largely as a result of the increasing use of molecular and chemosystematic techniques. The insight these methods have provided into bacterial evolution and classification has had a major impact on the circumscription of Pseudomonas, Xanthomonas and the phytopathogenic taxa within the family Enterobacteriaceae.