1. Please state project objectives and what work was done this quarter to address them: Objective 1: Study the changes in the reactive oxygen species (ROS) and investigate the correlation between ROS accumulation, sucrose levels and callose deposition in early season sweet oranges Infected trees were created by two combined methods – grafting and psyllid exposure. Infection rates are being determined currently. The polar metabolite, stored volatiles, released volatiles from leaves, stomata number and size, phenolic compounds, ROS, Nitric oxide, and starch content were measured in Parson Brown, Roble, and Hamlin, all on swingle and under controlled conditions and randomly organized. Draft of a manuscript will be ready by early 2024. Objective 2: Quantify fruit drop and canopy yield efficiency in Parson Brown as compared to Hamlin. Understand the underlying mechanism of better fruit retention and yield efficiency in Parson Brown as compared to Hamlin. In this quarter we have performed three monthly sampling for FDF of Parson brown and Hamlin fruit. We also collected the abscission zone and peel from both varieties and currently analyzing them for sugar content, phytohormones, and oxidative stress markers. Objective 3: Determine the mechanism underpinning the tolerance of Parson Brown to HLB by leaf volatiles and non-volatile metabolite analysis using GC-MS. Comparison in responses after infection will be measured in 2024. Responses will include but not be restricted to, symptoms, metabolic changes including hormones, and cellular responses including start accumulation and callose deposition. In addition to measuring the bacterial titer using a plasmid with a single copy unique CLas sequence for absolute cell quantification. Objective 4: Evaluate other early season sweet orangesLeaf samples have been collected from a Roble sweet orange grove in Zephyrhills. Additionally, samples from several survivor trees from a grove in Lake County have been collected. We have analysed the HLB status of these trees and the biochemical profile of the leaf samples. 2. Please state what work is anticipated for next quarter: Molecular and biochemical analysis of the HLB infected trees will be initiated. We will also collct samples in the fall from Roble and Hamlin trees 3. Please state budget status (underspend or overspend, and why): We are on track with the budget. A postdoc has been hired to work on several of the parameters in this project from the second quarter.