Abstract
More than 40 years have now passed since the development of the resistance of plant pathogens to fungicide treatments emerged as a major threat to crop protection. This opening chapter describes the appearance of resistant pathogen populations during this time, indicates their impact on crop disease management and reviews progress in detecting resistance and preventing or delaying its onset and spread. The evolution and management of resistance in different classes of fungicides (benzimidazoles, 2-aminopyrimidines, phenylamides, sterol demethylation inhibitors, dicarboximides and quinone outside inhibitors) are described.