This book is based on papers presented at the Second International Symposium on Bacterial and Bacteria-like Contaminants of Plant Tissue Cultures held at University College, Cork, Ireland in September 1996, with additional invited papers. Since the first symposium (published as Acta Horticulturae 225, 1988), there have been considerable advances in both plant disease diagstics and in the development of structured approaches to the management of disease and microbial contamination in micropropagation. These approaches have centered on attempts to separate, spatially, the problems of vertical disease transmission, via infected explants to progeny microplants, from laboratory contamination. Disease control is best achieved by establishing pathogen-free cultures, while laboratory contamination management is based on subsequent good working practice. Control of losses due to pathogens and microbial contamination in vitro addresses, arguably, the most important causes of losses in the industry; nevertheless, losses at and post establishment can also be considerable due to poor quality micro-propagules. In this book, a holistic approach to pathogen and microbial contamination control is evident with the recognition that micropropagators must address pathogen and microbial contamination in vitro, and diseases and microplant failure at establishment. There is increasing interest in establishing beneficial bacterial and mycorrhizal association with microplants in vitro and in vivo. The contents are divided into sections. In each section there are papers that update contributions offered at the first symposium; for example, major advances have been made in microbial taxomy and diagstics based on advances in DNA-based techniques. Consolidation has occurred in therapy and laboratory contamination management. Novel, and arguably speculative, in vitro contamination control based on autotrophic culture is described; and disease control at establishment using bacterial and mycorrhizal iculants is discussed.