In this reporting period, nine different variants were included for the optimization of T-SOL. These variants involved three different Zn chelating agents and three different concentrations of a plant surface permeability enhancer (with respect to metallic Zn). Interaction of metal chelating agents with Zn was characterized by UV-Vis and FT-IR spectroscopy which suggested binding of metal ions with the chelate functional groups (such as carboxyls, hydroxyls and amines). Microplate Alamar blue assay was used to determine the minimal inhibitory concentration (MIC) of the different variants of the T-SOL. The antibacterial efficacy of T-SOL variants with the chelating agents (1, 0.5 and 0.1M with respect to the metallic Zn) were screened against Escherichia coli and Xanthomonas alfalfae. The MIC of the T-SOL variants (all three chelate concentrations) was found to be in the range 80 ppm � 160 ppm (metallic zinc) for both E. coli and X. alfalfa. Interestingly, the MIC of the T-SOL prepared with agriculture-grade Zinc source was found to be 40 ppm (metallic zinc) for all the nine T-SOL variants when screened against both X. alfalfa and P. syringae suggesting that the antibacterial efficacy was not affected by the source of zinc. Preliminary trunk injection study has been initiated with T-SOL which contains a plant tissue permeable compound (inert) using a 2 Gallon size citrus plant. No noticeable phytotoxicity was observed after a week of injection of about 4.0 mL T-SOL (1000 ppm metallic Zn) formulation. In the coming reporting period, optimization of the synthesis protocol of T-SOL with agriculture-grade chemicals will be performed and their antimicrobial efficacy and phytotoxicity studies (foliar spray and trunk injection) will be conducted to narrow down the most effective T-SOL variant that can be later taken to green house and field trial studies.