The losses caused to staple crops by diseases and disorders and by depredations of pests are a worldwide problem at a time of population increase and food shortage. Plant pathology - basically the study of infectious diseases of plants - is therefore an increasingly important branch of applied science. An attempt is here made to provide a concise and straightforward account of the historical development of the diverse and interwoven themes of which the subject is composed. This may be read without reference to the documentation, which gives supplementary information and additional clues. The standpoint from which this survey is written is that, as for medicine, the right end of plant pathological practice is the diagnosis, treatment, and prevention of diseases and disorders. Emphasis throughout is therefore on the more practical aspects of plant pathological endeavour.