3(2 H )-pyridazinone derivatives: a new scaffold for novel plant activators.

Due to the emergence of drug resistance, pesticide residue and environmental contamination, it is important to develop novel eco-friendly strategies to protect plants. Among them, plant activators have been gaining more and more attention. Herein, based on SHAFTS method, a new scaffold for novel plant activators was predicted and the discovery and structure-activity relationships of a series of 3(2 H )-pyridazinone derivatives as novel plant activators were elucidated in detail. The vast majority of compounds exhibited excellent broad-spectrum induced resistance activity against tested diseases in vivo but no direct antimicrobial activity in vitro . Among them, compound 32 showed excellent efficacy against four pathogens and great potential as new plant activators in crop protection.