Research progress on screening methods for control agents against Citrus Huanglongbing

Citrus Huanglongbing (HLB), caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas), is a devastating disease of citrus worldwide. The inability to culture CLas in vitro has posed significant challenges for pesticide screening and development. This review systematically summarizes eight emerging methodologies for HLB pesticide evaluation: trunk injection, graft immersion with chemical soaking, foliar spray application, bioassays using phylogenetically related plant models, surrogate screening with HLB-associated pathogenic bacteria, semi-in vitro culture systems integrated with carbon quantum dot labeling, half-leaf method, and hydroponic culture-based screening. Furthermore, we critically analyze current pathogen detection methods and recent advances in anti-HLB compound discovery. This integrated analysis aim to facilitate the establishment of standardized protocols and harmonized evaluation criteria to accelerate HLB pesticide research.