Fungicides act in different way and at different sites of the metabolic cycle of fungal plant pathogens. Their mode of action, the species of fungal plant pathogen and agronomic factor determine wheter and how quickly the pathogenic fungus develop resistance to fungicides. There are many different ways for fungal plant pathogen to develop resistance. The most common mechanism is the structural change at the target site in pathogenic fungus. Mechanisms result in inactivity of the fungicide. There can be single- or multi-step resistance. It may occur suddenly or more slowly. It can be result of one or more mutations in the target organism. There are many different strategies to deal with or to prevent resistance. Strategies differ between major chemical groups of fungicides. There are eight working groups set up by FRAC, each of them dealing with the resistance on one major chemical group of fungicides.
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