1. Please state project objectives and what work was done this quarter to address them: Objective: To test OTC alone and in combination with Streptomycin and Zn at low and neutral pH (using a stabilizing adjuvant) in a commercial citrus grove. The trial was initiated at a commercial location in SW Florida. Trees are Valencia /X-639 planted in 2017. Baseline data were collected (tree size, canopy volume, canopy health). Leaves were collected for CLas analysis. Trees were injected in June. There were 10 treatments: 1. Low pH control (acidified water) 2. Neutral pH control (adjuvant) 3. Neutral pH+Zn 4. Low pH OTC 5. Low pH STM (streptomycin) 6. Low pH OTC+ STM 7. Neutral pH OTC 8. Neutral pH OTC+Zn 9. Neutral pH STM 10. Neutral pH OTC+STMLeaves were collected again 3 days and 1 month after injection.Trees experienced severe phytotoxicity with the neutral pH adjuvant alone (and in combination with OTC and STM). Low pH OTC injections also resulted in phytotoxicity, but less severe than the neutral pH treatments. Addition of Zn to the neutral pH adjuvant reduced phytotoxicity to the level of low pH OTC. No phytotoxicity was observed for low pH STM and the low pH control. Phytotoxicity ratings were conducted for all trees to quantify effects. We also started a small-tree experiment at the SWFREC farm, injecting low pH water and neutral pH adjuvant with and without OTC for destructively sampling after harvest to study the internal injury. The same phytotoxicity was observed after injection (more for the neutral pH treatments and less for the low pH treatments). Therefore, additional research is being done reformulating the neutral pH adjuvant for scalability and to minimize plant toxicity. For this, several industry-grade ingredients (chloride-free) have been tested for compatibility and performance of dissolving OTC at near-neutral pH. 2. Please state what work is anticipated for next quarter: Trunk wound sizes will be measured. Leaves will be collected for CLas and OTC detection. New adjuvant optimizations will be tested for toxicity on young citrus trees using the chemjet injection system. Formulation uptake, visual toxicity, and SPAD measurements will be used to determine the best candidate. 3. Please state budget status (underspend or overspend, and why):The subcontract was finally set up allowing us to start spending funds.