Most branches of science have what might be termed a 'core area' which is both related to and helps to integrate peripheral topics to form the overall subject area. Without this central link, the subject is simply a collection of disparate, albeit gener ally related topics. What genetics is to plant breeding, epidemiology is to the subject of plant pathology and, no matter what individual topic is considered, it is always possible to recognize the interaction with and relationship to epidemiological factors. Broadly speaking, until the 1950s, plant pathology was considered as the applied side of mycology and, indeed, the British Society of Plant Pathology was spawned from its mentor, the British Mycological Society, with considerable help from The Association of Applied Biology. However, with the exploding world popu lation and the growing demand for food, plant pathologists became increasingly aware of the need for a more considered, measured, precise and even holistic approach to their subject and, particularly, to plant disease management. Looking back over 40 years of teaching and research in plant pathology, it was very clear that the 'core' of the subject was epidemiology and that this 'new' study was developing a very distinct identity which was rapidly being recognized in its own right. The 'shotgun' approach to plant disease 'control' was quickly perceived to be too inexact and almost every aspect of the subject was being reviewed, refined and advanced.