Objective 1 – Ongoing. Objective 2 – Determine the phytotoxic levels of Fe + organic acid solutions on citrus. Preliminary range experiments were started using F11 to determine the concentration where leaf burn occurs. F11 is the Japanese Fe + citric acid product developed from the patent. In discussions with the Japanese inventors (who visited Florida to see the project), we just learned that another product, F11-C, is the product that was developed from this patent specifically for citrus. Therefore, we have modified all experiments, greenhouse and field, to use F11-C rather than F11. Aichi Steel, the manufacturer of F11 and F11-C, have provided us with all the product required for the project. Objective 3 – Determine the effect of Fe2+ + organic acid solutions on HLB titer using a rapid greenhouse, HLB-infected citron, rooted shoot bud assay. Being modified. Originally, we planned on using HLB-infected citron bud cuttings because they show clear HLB symptoms, but are still able to grow. This is unlike HLB-infected grapefruit that can barely be kept alive. However, in our experiments to characterize the citron system we have been able to detect very little growth differences between HLB-infected vs healthy citron plants. This means that treatment effects on HLB-infected plants cannot be determined, only the general effects on plant growth. We are working on another system based on very young sweet orange plants and psyllid inoculation where the preliminary experiment looked very promising. The HLB effect was very strong, the requirement for a good system to test treatments. The validation experiment is now being rerun at a larger scale. If it validates, then we will use this system on the objective 3 (and objectives 4 and 5) experiments where it should work quite well. Objective 4 – See objective 3 discussion.Objective 5 – See objective 3 discussion. Objectives 6 and 7 – These are the field tests for the various ferrous iron (Fe2+) and citric acid treatments on HLB status and horticultural measures for both mature (HLB symptomatic) and nonbearing (non-symptomatic) trees. As reported in the previous progress reports, both tree classes have been measured and recorded for baseline ground data. Likewise both classes have been flown with a camera equipped UAV and aerial data has been documented and analyzed. Tree dimension data for both ground and aerial data have been correlated and display a significant degree of accuracy. In this quarter, 8 treatment applications have been performed. After the initial application, phytotoxic assessments were made for each treatment at 5 DAT and 10 DAT. Virtually all the ferrous iron (Fe2+) products with citric acid exhibited minor leaf burn whereas the chelated iron products did not cause burn. The nonbearing trees as a class are exhibiting vigorous growth and excellent health in that they do not reveal any HLB symptoms whereas the mature trees continue to exhibit moderate decline due to HLB. Neither tree classes reveal any visually discernable treatment effects.