In Central Florida (Lake Placid grove), all data regarding tree height and canopy as well as canker and HLB incidence were collected. Also samples for time 0 nutrient analysis and auxin quantification were collected. Unfortunately, hurricane Ian destroyed many trees and produced a great amount of fruit drop, so Hamlin plots were harvested before we could finish our work for this year. In Southwest Florida (Duda farms) we have characterized all trees used (tree height and canopy volumes) and we started assessing HLB and canker incidence. For HLB, most of the trees we are using category 3 = 26-50% of the canopy with foliar disease symptoms, and category 4 = 51-75% of the canopy with foliar disease symptoms. Canker incidence is so far negligible. We have collected samples for leaf nutrient analysis and auxin quantification. We started treatments with the three advanced liquid Zn products (Zinkicide TMN111, FertiZink, and NuZinc Trees under treatments continue are showing greener canopies than controls. Control trees are presented some off-blooms still in September and October. These off-blooms have not been observed in the treated trees. Fruit drop is being recorded in Hamlin weekly. Unfortunately, hurricane Ian has increased fruit drop but since we are collecting data weekly, we are going to be able to reduce the fruit drop background noise and in any case, see if our treatments had a beneficial impact even under hurricane conditions in alleviating fruit drop. We have lost also some trees due to the high wind. Interestingly, all of the trees were lost in a control plot. Other treatments in the same grove with commercial Zn sulfate are showing the same effects. We do not have a clear explanation for this, but fortunately, treatments were not compromised and other trees in untreated plots are being used as new control replacements.To evaluate the oxidative properties of the FertiZink and NuZinc product formulations, Amplex Red based reactive oxygen species (ROS) assay was performed to measure the production of ROS. Neither of the formulations significantly produced ROS even at 28,000 ppm Zn. This results suggest that the formulations would not cause oxidative stress to plants upon foliar application. Dynamic Light Scattering (DLS) studies were conducted on two batches of FertiZink and NuZinc that were fresh and 1 year old at the time of evaluation. Measurements were conducted at 400ppm and 800pm Zn to replicate field spray application rate. The DLS studies of the products showed the presence of micron and sub-micron size particulates, confirming that the products are not in the nano-regime. We also noticed sedimentation of products during the DLS measurements, which resulted inconsistence readings. This inconsistency was apparent in both the 1 year old batch and the fresh batch. Assessment of the particle size will be performed through scanning electron microscopy. Work anticipated for next quarter: We anticipate that Hamlin fruit will be harvested. This has not done yet as Brix in general are around 8.2 (December 13, 2022), but slowly increasing. Treatments will continue in Valencia trees.Outreach: Alferez, F. Understanding and Managing Fruit Drop in HLB-Affected Citrus. Invited Seminar at American Society of Horticultural Science. January 12, 2023.