Evidence based resistance management

The control of fungal plant pathogens has been characterised by repeated cycles of introduction of new fungicides and for many of them a subsequent loss of efficacy due to the emergence and selection of resistant pathogen strains. Several strategies have been proposed to prevent, or at least delay, resistance problems. Such resistance management strategies should be based on evidence interpreted within a sound experimental and theoretical framework. Industry and regulatory decisions about fungicide resistance management often cannot wait for the accumulation of new evidence, so decisions should be taken by weighing the existing evidence. In discussions on resistance management, it is often not explicit what the evidence is. In this chapter, we review experimental and modelling evidence on (1) the choice of application dose, (2) the number of applications, (3) the use of fungicide mixtures, (4) the use of fungicide alternation and (5) protectant versus curative fungicide application. At several places in the text, we stress that resistance management should not compromise effective disease control.