Salicylic acid: a key natural foundation for next-generation plant defense stimulators

The field of crop protection is undergoing a major transition. The use of conventional biocidal compounds, which have dominated plant protection since the mid-20th century, is now being questioned by societal demands for alternatives that are environmentally friendly and safe for human health. Consequently, new agronomic strategies are needed to ensure sustainable disease management. Among these, the activation of natural plant defenses against pathogens has emerged as a key approach and forms the central theme of this review. Salicylic acid (SA), a seemingly simple bifunctional aromatic compound, plays a pivotal role in plant immunity and in the establishment of systemic acquired resistance (SAR). However, its practical use is limited by rapid metabolism, compartmentalization, and potential phytotoxicity. To overcome these constraints, numerous SA analogs and derivatives have been developed to mimic or prolong its defensive action. A particularly promising, though still underexplored, approach involves the design of mobile bioprecursors and controlled-release formulations capable of distributing throughout the plant and gradually releasing SA or related active species. Such approaches could sustain defense activation over extended periods while minimizing metabolic and environmental costs, paving the way for next-generation plant defense stimulators. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.