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. A)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:Fertilization treatments for the year were only partially complete in June and too early for fruit quality and preharvest drop analyses. Routine measurements of tree health and performance continued, including leaf nutrient analyses, chlorophyll index, canopy and trunk size, fruit growth rates and incidental fruit drop (not pre-harvest). Leaf nutrient concentration in the citrus leaves was affected by fertilizer application timing. Initially, fertilizer application of 20-25% of total recommended dose during February recorded low concentration of N,Ca, Mg, S and Zn. However the nutrients P, K, Cu, Fe and B were observed in optimum range in Hamlin and Valencia. After 50% fertilization of total recommended N (180lbs/ac, year 2 rate) by March, optimum to higher ranges of N concentrations were observed. In contrast, N concentration in Hamlin was observed below optimum ranges if only applied 25% N fertilizer was applied by March. This result suggests that 50% of recommended N application by March improves the N uptake in Hamlin variety and could be beneficial for tree growth and fruit development. Fruit drop was noticeably increased with time in Hamlin variety after natural fruit drop (June) but with no significant difference among treatments (fertilization timing and rate). See Issues, below. Routine lysimeter leachate sample collection continued in this quarter but sample analysis was not completed yet.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):There were no new fruit quality of drop data for 2023 to report in June, but so far trunk diameter, fruit growth and fruit drop were not significantly different with respect to fertilizer treatments.B) New developments: NoneC) Issues: The Hamlin trees dropped some low-hanging fruit after a routine glyphosate spray applied by the grove care crew. The Valencia trees were mostly unaffected, in part due to their fruit not hanging as low as the larger Hamlin fruit.2. Please state what work is anticipated for next quarter:Routine lysimeter sampling, leaf sampling, processing and analysis will be ongoing, as will tree size, root growth and fruit drop and growth measurement.The fourth fertilizer application will be applied in late August, phase 2 fruit growth.3. Please state budget status (underspend or overspend, and why):Spending rate is approximately on track.