During the 1990s, research on Pseudomonas syringae pathovars and related pathogens has progressed rapidly, opening up many new avenues. The application of molecular genetics has provided insights into determinants of pathogenicity and virulence. Progress has also been made in elucidating the chemical structures and modes of action of phytotoxins from Pseudomonas syringae; by establishing strategies for disease control; in biotechnological applications; by studying the resistant reaction of the plant with a combined biochemical and genetic approach; and in the development of detection and identification methodologies as tools in epidemiological studies. In a response to such rapid advances, this volume is an attempt to provide a balanced overview of recent developments in the field. At the beginning of each chapter is a critical review by international experts.