In the initial phase of this research project, development of field work protocol and fertilizer solution chemistries for the greenhouse portion have been the primary focus. Grove test site selection is still underway and once all of the grove sites are identified, the bulk of the field data collection work will begin. Of the four primary objectives, one and two have been the primary focus. Objective 1: Leaf nutrient thresholds We are working to identify and select groves that will be suitable for this phase of the research. One of the groves identified on the CREC campus was used to test the protocol of the work to be done on a regular basis. LAI, tree canopy volume, PCR, soil samples, and leaf tissue nutrition were all measured. Leaves for nutrition were measured for chlorophyll index (SPAD), leaf area, dry mass, and scanned using a flatbed scanner for color as well as leaf circumference and leaf area. Objective 2: Determine soil conditions that favor root health, including root hair and VAM proliferation i. While groves are still being selected for this research, the preliminary work, as mentioned in Objective 1 above, has been done and includes the soil sampling at the 0-6 inch and 6-12 inch depth. ii. Cuttings were taken from both healthy non-infected (HLB-) trees as well as HLB+ infected trees. These cuttings were rooted using plastic seed germinating domes to limit transpiration. After the cuttings rooted, they were switched to aeroponics chambers for further root development using standard fertilizer solutions. In the meantime, solution chemistries were developed to contain the correct mix of nutrients for the target phosphate concentration using soluble phosphorus, tricalcium phosphate (TCP) and rock phosphate (RP). Initial groups of HLB suspect cuttings were placed into three aeroponics chambers with specific nutrient chemistries. Those chambers are, Chamber 1, complete fertilizer minus soluble phosphate and using TCP; Chamber 2, complete fertilizer minus soluble phosphorus and using RP; and Chamber 3, complete fertilizer solution with soluble phosphorus. The purpose behind the use of solid TCP and RP is to establish stable solid-liquid equilibria that regulate concentrations of P and Ca in solution for optimizing root growth and health. We succeeded in establishing stable chemical equilibria with both PR and TCP in the slightly alkaline pH range, and the trees are now being grown in aeroponics to monitor and measure root proliferation.