Progress report for the second quarter of the 2019/2020 project yearThe purpose of the project is to develop new guidelines for restoring root health and improving overall tree nutrition for Florida oranges and grapefruit. The objectives of the project are to:1. Determine optimal nutrient concentrations in roots and leaves for multiple grapefruit and orange varieties.2. Compare and contrast fertigation, soil, and foliar fertilization to identify best application method for uptake of nutrients into both underground and aboveground components.3. Investigate the relationship between root and leaf nutrient contents to tree health, yield, and fruit quality as well as bacteria titer.4. Generate updated and new guidelines for optimal nutrient contents for roots and leaves for HLB-affected trees. Progress to date:The project is being conducted at three sites: Citrus Research and Education Center (CREC), Southern Gardens Citrus near Clewiston, FL and Indian River Research and Education Center (IRREC). Data collection continued during this quarter on root scanning, canopy size determinations and soil sampling on the central Ridge and southwest Flatwoods. While it is early to determine some trends, it appears soil and root nutrient levels, for example, follow the pattern of treatments e.g. 4x>2x>1x, for soil applied treatments. Similarly, for foliar applied treatments, the pattern in leaf nutrient concentration follows 1x<2x<4x. We are following through with correlations in roots, leaves and soil with canopy size, trunk size, yield, bacteria titers and so forth. Root growth tends to be more pronounced with soil applied nutrients compared with leaf applied nutrients and this will be confirmed and validated further in the following year of measurements. At the southeast Flatwoods, all grove caretaking activities were performed on time and the treatments have been applied as expected along with data collection on tree size, soil/leaf/root nutrient levels, and HLB ratings. All sampling for the third quarter is complete and data analysis is underway and will be reported in the next quarter. Graduate students Tanyaradzwa Chinyukwi and Lucas Hallman presented portions of their research at the American Society of Horticultural Science virtual Annual Meeting between August 10 to 13, 2020. Plans for Next QuarterThe team will continue with fertilizer treatments and data collection including HLB rating assessments, canopy size and root growth measurements and reporting on the progress of the project. Graduate students working on the project will present at the Florida State Horticultural Society. One graduate student working on the project will be submitting her MS thesis to the UF graduate school this fall and will prepare articles for refereed journal publications.