1. Please state project objectives and what work was done this quarter to address them:Objective 1. Collect field performance data from replicated rootstock field trials and release new rootstock cultivars as justified by superior performance in multiyear field trials.Collect field performance data. Thirty-one USDA replicated rootstock trials are active. For the current quarter, canopy health data was collected from all trials, and for the ten bearing trials with Valencia scion, fruit yield and fruit quality data was also collected from about 4500 experimental units (replications). Juice quality evaluations continued on samples from other trials with early maturing scions.During this quarter, seedlings of a select group SuperSour rootstocks with outstanding performance were grown for assessment of trueness-to-type from seed in preparation for cultivar release for commercial use.Preparation for release. The most promising USDA rootstock selections that may be released in the next 2 years were previously provided to the FDACS-DPI program for shoot tip grafting and disease testing. Those have been completed in the DPI program and are currently available for commercial nursery propagation, following the decision for official release by USDA.Release of new rootstocks. New rootstocks will be officially released by USDA for commercial use when justified by superior peformance in multi-year replicated field trials. The rootstocks US-1688 and US-1709 have been proposed for release, and are in the second stage of approval by USDA. It is anticipated that these rootstocks will be named US SuperSour 4 and US SuperSour 5, and will be released and commercially available sometime in 2023.Objective 2. Create hybrid rootstocks that combine germplasm from parental material with good rootstock traits and HLB tolerance, propagate the most promising of these hybrids, and establish replicated field trials with commercial scions.Create hybrids. Selected new crosses were completed in this quarter with twenty high-priority parental combinations based on the most recent information about heritability of important rootstock traits. Fruit set was scored and will be followed until harvest of the hybrid seed.Propagate hybrids. Budded trees in the nursery for a rootstock trial with a new high-quality scion continued to be grown and developed for field planting in 2023. New rootstocks with the most superior performance were selected from stage 1 trials and liners propagated, in preparation for budding of trees with Valencia in summer of 2023. It is anticipated that these trees will be ready for field planting of two new rootstock field trials in spring 2024.Establish replicated field trials. No new field trials were planted this quarter.Tree care in trials. Periodic care was applied in the 31 field trials to maintain tree health and productivity, and manage weeds.2. Please state what work is anticipated for next quarter:For the coming quarter, work will focus on completing the juice quality analysis from the Valencia field trials, collection of tree size and canopy health data from all the trials, continuing propagation of trees for future trials, and care of existing trees in trials. Greenhouse and laboratory work will also continue with focus on assessment of trueness-to-type from seed for the most promising rootstocks using SSR methodology.3. Please state budget status (underspend or overspend, and why):Budget is on schedule to be spent out by the end of the first year. The project was fully staffed, and work is progressing as planned.