�The purpose is to evaluate the control effect of bactericides via trunk injection. This proposal addresses the following CRDF CPDC-18 Research Priorities: 1A, 1C, and 1D. To achieve the goal of the research, we are conducting the following objectives:Objective 1. To illustrate whether application of bactericides via trunk injection could efficiently manage citrus HLB and how bactericides via trunk injection affects Las and HLB diseased trees.Three field trials have begun to investigate how the application of bactericides via trunk injection affects citrus growth, production, HLB symptom development, and Las population in different aged trees at different levels of HLB disease severity.�We evaluated the inhibitory activity of OTC against Las in greenhouse and field experiments. Citrus trees were trunk-injected with OTC, and leaves were inspected for Las populations and OTC residues using qPCR and HPLC assays respectively, at various times after OTC treatment. We have acquired data about the MBC of OTC in planta. A manuscript is under preparation.�Objective 2. To examine the dynamics and residues of bactericide injected into citrus and systemic movement within the vascular system of trees and characterize the degradation metabolites of bactericides in citrus.�A field trial has begun to determine the concentrations of bactericides in leaf, stem, root, flower, and fruit using� HPLC at the following time points: 2, 7, 14, 28 days, 2, 4, 6, 8, 10, 12 months after injection at different doses. The leaf samples are being collected at different time points for testing.�Objective 3. To determine whether trunk injection of bactericides could decrease Las acquisition by Asian citrus psyllids (ACP).In this objective, we will determine whether trunk injection of bactericides at three different doses could decrease Las acquisition by ACP in greenhouse and in the field. We are conducting the experiment right now.�Objective 4.�To monitor resistance development in Las against bactericides and evaluate potential side effects of trunk injection of bactericides.�Las-specific primers were designed to target the putative binding sites of OTC in 16SrRNA gene of Las. Plant genomic DNA was extracted from citrus trees received OTC injection for three years. PCR were performed with the primers and DNA samples, and the products were purified and subjected to DNA sequencing. No mutation was identified yet. We will continue to monitor the resistance development against OTC and Streptomycin. We have collected more samples from multiple citrus groves.���