This book is based mainly on invited and offered 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. The First International Symposium on Bacterial and Bacteria-like Contaminants of Plant Tissue Cultures was held at the same venue in 1987 and was published as Acta Horticulturae volume 225, 1988. In the intervening years there have been considerable advances in both plant disease diagnostics and in the development of structured approaches to the management of disease and microbial contamination in micropropagation. These approaches have centred on attempts to separate, spatially, the problems of disease transmission and laboratory contamination. Disease-control is best achieved by establishing pathogen-free cultures while laboratory contamination is based on subsequent good working practice. Control of losses due to pathogens and microbial contamination in vitro addresses, arguably, the most importance causes of losses in the industry; nevertheless, losses at and post establishment can also be considerable due to poor quality microplants or micro-shoots. In this symposium, 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.