1. Please state project objectives and what work was done this quarter to address them: The overall goal of the project is to develop fertilization strategies to best match nutrient supply and demand, and develop recommendations for optimal nutrient application timing as compared to a simple constant supply, which will improve fruit yield, quality, and reduce fruit drop. Objective 1) Test if a reduced N-P-K nutrient supply in the fall is safe for sustaining HLB-affected citrus, and whether it can improve fruit quality to facilitate earlier maturity / harvesting and reduce fruit drop: In order to compare the effects of early versus late / sustained fertilization on health and fruit production of Hamlin and Valencia trees, the following completed treatments were evaluated in the third quarter of 2022:Treatments: Early fertilization as % completed of the recommended fertilization (RF; 160 lb N/acre) before June T1: 25% of RF (T25%)T2: 50% of RF (T50%)T3: 75% of RF (T75%)T4: 100% of RF (T100%)The remaining mid- to late-season fertilizer treatments were applied during the third quarter and the results will be reported in the following quarter. Leaf samples were collected on monthly intervals and analyzed to determine the leaf nutrient concentrations. The preliminary results showed that if 50% of total nutrient requirement was applied before May, there was improvement in tree health (NDVE) and vigor (NDVI) indices, and canopy volume. The same treatment resulted in higher leaf nutrient concentrations but only nitrogen was statistically significant. The fruit growth (diameter) was not significantly difference between early fertilization treatment even applying 75% or 100% of total fertilizer. Early fertilization with higher rates increased fruit size but growth increments diminished over time in all treatments, as expected when fruit development enters growth stage 2 in summer.Preliminary results showed that there was a positive trend of crop health, fruit growth and leaf nutrient concentration with early higher fertilization but didn’t observe statistically significant differences.Objective 2) Develop an optimized, practical fertilizer timing management profile to boost fruit quality and reduce fruit drop for HLB-affected citrus based in part on the sigmoidal nutrient demand curve defined by four physiological growth phases (0=bloom/fruit set; 1=cell division; 2=cell enlargement; 3=maturation):The growth and yield data associated with all different timed fertilizer events in year 1 is not complete yet and therefore we don’t have new results to report for this objective. Our investigations to use the intensity of leaf symptom expression throughout the season to help determine foliar nutrition in the field with smartphone apps is continuing.B) New developments: The Sugarbelle trials focusing on solving the soft fruit quality issues are progressing well. We have now applied three replicated foliar spray treatments to Sugarbelle trees at the city block and on healthy trees in the CUPS, consisting of KNO3 and KH2PO4. The purpose of the sprays is to increase peel thickness and strength to avoid soft fruit, as well as to improve fruit size. C) Issues: The fruit drop and tree lodging/ branch breaking damage caused by hurricane Ian to the outdoor Hamlin, Valencia and Sugarbelle experiments is considerable. The Sugarbelle experiment in the CUPS sustained no damage. We expect that the reduced yield data will not be useful for calibrating the fertilizer timing models, but we will collect and use fruit quality data where possible. 2. Please state what work is anticipated for next quarter:The final late fertilizer applications will be made to designated treatment plots in November. Soil, lysimeter sampling, leaf sampling, processing and analysis will be ongoing, as will tree size and fruit measurement. We plan to assess fruit yield and quality for the Hamlin and Sugarbelle experiments in December / January. The third Aerobotics drone survey will now fly in late November due to delays from Hurricanes Ian and Nicole. 3. Please state budget status (underspend or overspend, and why):Spending rate is approximately on track.