Copper continues to be used as antibacterial/antifungal agent for citrus crop protection due to its effectiveness and affordability. However, prolonged and aggressive use of copper compounds has raised concerns due to copper accumulation in agricultural soil and development of bacterial resistance. This demands a search for suitable Cu alternatives. The goal is to develop Quaternary ammonium compound (Quat) based bactericide as an alternative to Cu compounds. Quat exhibits strong antimicrobial properties. However, direct foliar spray of Quat to plant is not practical as it causes severe phytotoxicity. Moreover, Quat is highly soluble in water, therefore exhibits poor rainfastness. This project is focused on developing Fixed-Quat formulations which will overcome phytotoxicity and rainfastness issues of Quat material without compromising its strong antimicrobial properties. A series of Fixed-Quat materials are being developed using three different EPA approved Quat materials. In this reporting period, two most promising Fixed-Quat nanogel and a Fixed-Quat nanoparticle formulations have been synthesized which remained stable for over two months. Scanning Electron Microscopy (SEM) characterization of Fixed-Quat nanogel material has revealed the formation of highly polydispersed submicron to micron size silica-gel particles. Phytotoxicity studies have been carried out on Vinca sp. (known to be highly susceptible to phytotoxicity and often used in agricultural industry as model test plants) to observe any potential plant tissue damage from Fixed-Quat materials. Phytotoxicity results (observed for 72 hours) have shown zero plant tissue damage when applied at rates as high as 900 ppm. Antibacterial studies have been conducted using in-vitro microplate alamar blue assay, bacterial viability expressed as colony forming units (CFU/mL) and growth curves using gram-negative model bacterial system, E coli. Optimized versions of these formulations showed complete bactericidal efficacy at concentrations as low as ~ 2ppm over our previously reported ~8ppm concentration. One of the Fixed-Quat nanogel materials (containing all EPA approved ingredients) has been delivered for 2014 field trials. Field efficacy will be evaluated at two different foliar spray rates.