Extracts From Perilla frutescens and Artemisia argyi Offer a Novel Strategy for Sustainable Integrated Management of Citrus Huanglongbing

Citrus Huanglongbing (HLB), a devastating global citrus disease caused by the unculturable phloem‐limited bacterium Candidatus Liberibacter asiaticus ( C Las), poses a significant threat to citrus production. Addressing the challenges associated with the in vitro culture of C Las and the limitations of current chemical control strategies, such as drug resistance and environmental pollution, this study investigated the potential of traditional Chinese medicinal extracts. In vitro antimicrobial assays revealed that extracts from Perilla frutescens ( P. frutescens) , Artemisia argyi ( A. argyi ), and their combination exhibited concentration‐dependent growth inhibition against two C Las close lineage bacteria like Agrobacterium tumefaciens GV3101 (GV3101) and Sinorhizobium meliloti 1201 (S.M), as well as antimicrobial activity against plant pathogens like Pseudomonas syringae pv. Maculicola ( Psm ) ES4326/ AvrRpt2 and Pseudomonas syringae pv . Tomato ( Pst ) DC3000/ AvrRps4 . These extracts significantly reduced C Las proliferation in leaves of Catharanthus roseus (periwinkle)and Citrus . RT‐qPCR analysis indicated a significant upregulation (three‐ to fivefold increase) of key marker genes NPR1 (non‑expressor of PR genes 1, a master regulator of SAR), PR1 (pathogenesis‑related 1, a marker of SAR) of systemic acquired resistance (SAR) and RBOHD (respiratory burst oxidase homolog D, a ROS‑producing enzyme in PTI) of pathogen‐associated molecular pattern‐triggered immunity (PTI) pathways. Notably, these extracts exhibited a repellency rate exceeding 90% against adults of the Diaphorina citri (Asian citrus psyllid). Field treatment further confirmed its efficacy in reducing C Las. This study is the first to systematically reveal triple functions of P. frutescens — A. argyi extract, encompassing “antibacterial activity, immune activation, and vector control,” offering a novel strategy for the sustainable integrated management of HLB, this eco‐friendly alternative exhibits significant potential for the biocontrol of plant diseases and insect pests.