The purpose of the project is to develop new guidelines for restoring root health and improving overall tree nutrition in 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 implemented at the 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 in the third quarter particularly on canopy size, soil and leaf nutrient concentration, and root growth. Data collection will continue, and analyses will be done as needed. Updates and data will be presented in future extension meetings after about a year or two of data collection and validation of results to get feedback from growers and the citrus industry. In addition to one graduate student working on the project CREC, a second graduate student started working on the project this summer at the IRREC. The project has also recruited agricultural assistants to support data collection and other measurements. Recruiting at IRREC is taking longer than expected due to the lack of interested and/or qualified applicants. A pool of applicants from an advertisement at Craiglist is under review. One candidate has been identified and is in the process of being hired. Drs. Ferrarezi, Rossi and Wright also decided on conducting the trial at the IRREC Research Grove since we were not able to identify a grower collaborator to partner up due to the challenges of implementing a fertigation system in a commercial grove. Trees planted in double row, high-density staggered in diamond set (392 trees/acre) were cut down to one row (196 trees/acre) for the trial. Plans for Next QuarterThe team will continue with data collection and reporting on the progress of the project.