A Comprehensive Investigation of Hydrazide and Its Derived Structures in the Agricultural Fungicidal Field

Hydrazides are present in many bioactive molecules and exhibit a variety of biological activities, such as insecticidal, herbicidal, antifungal, antitumor, and antiviral effects. In this Review, we review the application of hydrazide and its derived structures in the agricultural fungicidal field, including monohydrazides, diacylhydrazines, hydrazide-hydrazones, and sulfonyl hydrazides. In addition, the antifungal mechanism of action of the hydrazide derivatives was analyzed and summarized, mainly involving succinate dehydrogenase inhibitors, laccase inhibitors, and targeting plasma membranes. Finally, based on the structural analysis of the novel fungicidal lead compounds, the structure–activity relationship of the hydrazide derivatives was constructed and the development trend of hydrazide structures in fungicidal applications was prospected. It is hoped that this Review can provide some significant guidance for the development of new hydrazide fungicides in the future.