1. Please state project objectives and what work was done this quarter to address them: The zinc formulations were obtained from TradeMark Nitrogen Inc. and Santra’s Lab to support this year’s field trial. We continued foliar sprays applied every 6 weeks at two different rates (400 and 800 ppm Zn). Trials were conducted on both Hamlin and Valencia oranges. -Tree health continued improving by foliar application of Zn and that particulate Zn fomulations improved tree health more than soluble Zn (Zinc Sulfate). We harvested Hamlin trees on January 12 in Southwest FL. We measured a significant increase in yield with Fertizink treatment (246 boxes/acre), irrespective of the dosage used, as compared to controls (191 boxes/ acre). Nuzink also increased yield (219 boxes/acre) but this difference was not statistically significant at p<0.05. These results are coincident with last season's (were we had hurricane Ian as an external factor), but then only 800 ppm Fertzink increased yield in Hamlin. Next season we will need to further determine if both concentrations have the same effect on yield, as this will be important for economics in grove management. -We also monitored fruit drop, and it was significantly reduced by 30% on average in all treatments until December in Hamlin. From December to January, fruit drop was the same in all treatments including control fruit. This suggests that in the absence of a significant increase in internal quality (internal quality was not affected by the treatments and Brix were around 9) it may be judicious to harvest in early December instead of January and increase yield even more. -We have extracted all samples for auxin analysis and we have started to determine auxin content in peel and abscission zones. - Nuzinc and Fertizink at 800 ppm Zn were evaluated to determine what percentage of Zn is soluble and insoluble. Nuzinc was determined to have 87.01% of Zn in ionic form and 12.99% insoluble Zn, while Fertizink had 99.43% insoluble Zn. These results might explain why there is a difference in performance between Nuzinc and Fertizink. -We have treated seedlings with Zinc sulfate, Nuzinc or Fertizink to measure the rainfastness, track the absorption and translocation of Zinc seven days after treatment. The tissue digestions has been performed but quantification is still pending. 2. Please state what work is anticipated for next quarter: In the next quarter we will harvest Valencia and continue auxin determination. Moreover, the difference in Zn rainfastness, absorption and translocation will be quantified. 3. Please state budget status (underspend or overspend, and why): on track