Carboxylic Acid Amide ( CAA ) Fungicides

This chapter provides comprehensive insights into the complexities of chemical synthesis, physiochemical properties, biological activity, mode of action, and mechanism of resistance of carboxylic acid amide (CAA) fungicides. Three commercial subclasses can be distinguished: the cinnamic acid amides, including dimethomorph, flumorph, and pyrimorph; the valinamides, with iprovalicarb, benthiavalicarb, and valifenalate; and the mandelamides, with mandipropamid. In addition, several experimental subclasses, such as aminosulfones, N -sulfonyl amino acid amides, glyoxylic acid amides, and quarternary α-cyanobenzylsulfonamides, are also highlighted. CAA fungicides specifically inhibit cellulose synthase 3, controlled by the CesA3 gene, in the biosynthesis of the (cellulose-containing) cell walls of oomycetes. Cross-resistance exists among all CAA fungicides encoded primarily by one recessive mutation in the CesA3 gene at position 1105.