1. Please state project objectives and what work was done this quarter to address them: The overall objective in this proposal is to explore whether FANA oligonucleotides, which are synthetic RNA-based synthetic molecules that mimic DNA and inhibit bacterial gene expression can be used to mitigate CLas in infected trees.The first objective of this project is to s screen FANA antisense oligonucleotide targeting CLas for efficacy in a field trial. Treatments were applied to 10-year-old, CLas-infected Valencia trees of a standard size and CLas titer. FANA ASOs complementary to two CLas essential genes F(ANA-L and FANA-H), a scramble sequence control (FANA-SC), oxytetracycline (Fireline) and insecticide-only treatments are were applied to 15 trees in 1-acre plots, replicated five times in a randomized complete block design. Treatments are applied using microinjection of dosages determined in our previous greenhouse assays.Prior to treatment 1 (T1), four leaves were removed from each tree, two from each side of the apex of the tree and two from each side of th20%e base of the canopy, to determine initial CLas titer (T0). PCR of these leaves and leaves collected post treatment was conducted during Q2 of this project to monitor the effect of the FANA ASOs on the CLas titer of each tree. Pathogen titers in trees before treatment was determined using a quantitative real-time PCR (qPCR) assay. Trees were uniformly infected with mean Ct (qPCR cycle threshold) values ranging from 24 to 25. Oxytetracyline (Fireline) was initially the most effective in preventing increases in CLas titers, followed by FANA L. CLas titers increased 2 d following all other treatment applications. The percent increase in CLas Ct value was greatest in the FANA-H and insecticide-only treatments. Sample processing is still underway to assess the effect of treatments on tree infections7, 30, and 60 d after treatment applications. We expect that the treatments will take time to move throughout the trees and reduce CLas infection. The second objective is to evaluate FANA antisense oligonucleotide targeting CLas in order to reduce vector transmission. Single females from uninfected laboratory cultures were caged on young leaf growth (flush) of treated or control infected trees for oviposition. Each treatment was replicated ten times on individual trees. Due insufficient survival of ACP in March 2022, this experiment was carried out in May-June2022 and is still underway. Adult psyllids have been collected from trees and are being process to assess acquisition. F1 adults will be collected in late June to assess acquisition during nymph development and to use in inoculation assays. 2. Please state what work is anticipated for next quarter: Objective 1:Samples from first round of treatment applications through day 60 will be processed during quarter 3. A second round of treatments will be applied at the end of quarter 3. Objective 2: Results of acquisition assay #1 with P1 and F1 adults will be next quarter. Inoculation assays will also be completed in Q3, with samples collected for CLas detection. If rootstocks are used for inoculation, plants will be held for development of CLas infection and symptom development. 3. Please state budget status (underspend or overspend, and why): Our budget is on track for the project. FANA treatments, which are the largest portion of the budget, have been purchased for the experiments. Micorinjectors and research plot charges have also been spent. Remaining budget will be spent to process samples, ACP assays, and on personnel.