Flavonoids as Antimicrobial Pesticides: Mechanisms of Action, Formulation Strategies, and Perspectives for Pre- and Postharvest Disease Management

The global spread and incidence of microbial phytopathogens are expected to increase due to climate change and the intensification of international food trade, threatening crop productivity. While pesticides remain essential for managing disease severity, European regulations and initiatives, such as the Green Deal, have emphasized the urgent need to reduce their indiscriminate use, which has contributed to pest resistance, environmental contamination, and human health issues. Botanical pesticides, particularly flavonoids, represent promising complements to traditional pesticides because of their diverse composition of antimicrobial agents. Therefore, this review provides an overview of the antimicrobial potential of flavonoids for microbial phytopathogens, focusing on agricultural fungal pathogens and bacterial phytopathogens. The mechanisms of action by which flavonoids exert their pesticidal activity are detailed, along with structure–activity relationships, formulation, and market perspectives. The literature reveals that flavonoids possess strong potential against pre- and postharvest crop diseases caused by fungal and bacterial pathogens owing to their ability to exert multisite activity, although limited data is verified for antibacterial studies. However, their successful transition to the pesticide market requires field performance validation, formulation technologies, toxicological assessment, and regulatory harmonization.