The seventeenth symposium of the British Mycological Society was held jointly with the British Society for Plant Pathology and the Society of Irish Plant Pathologists. The subject of the symposium was Phytophthora, the organism responsible for many plant diseases, most notably potato blight. This 1991 book presents the results of the meeting in a wide-ranging volume incorporating chapters discussing the history of potato blight, host-pathogen reactions, systematics and intraspecific variation, molecular and genetic studies and the development of effective control methods. Arguably the most studied of all plant pathogens, Phytophthora remains a problem in modern agriculture.