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 USDA replicated rootstock trials are active. For February-April 2024, tree survival, cropping and juice data was collected from eight Valencia rootstock trials. Juice analysis of frozen samples was conducted for early trials from the 2023-24 season. Renovation of the fruit processing lab at USHRL was initiated, and will involve installation of a new autotitrator, refractometer, spectrophotometer, and data management system that will greatly improve workflow and increase the capacity to process fruit samples. During this quarter, planting of stored seed began on candidate SuperSour rootstocks that will be used for morphology and SSR assessment of trueness-to-type from seed for selections tentatively considered for release over the next three years. Additional work on trueness-to-type assessment and salinity tolerance of new rootstocks was also continued. Cooperative work was continued to assess US rootstocks for resistance/tolerance to citrus nematode, sting nematode, and other traits.Release of new rootstocks. New rootstocks will be officially released by USDA for commercial use when justified by superior performance in multi-year replicated field trials. The most promising USDA rootstock selections are provided to the FDACS-DPI program for shoot tip grafting and disease testing in advance of potential release. The two newest USDA rootstocks, US SuperSour 4 and US SuperSour 5 released in September 2023, were propagated for planting in upcoming demonstration plantings and field trials. Plans are also being made to include these newest rootstocks in the next phase of CRAFT. Eight other promising new USDA rootstocks are planned to provide to DPI for STG and testing in 2024, in preparation for possible release in future years.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. About 230 hybrid seedlings from 2023 high priority crosses are being grown in the greenhouse this quarter for preliminary evaluation and further testing.Propagate hybrids. About 1500 trees for two new stage 2 rootstock trials with 35 advanced selection SuperSour rootstocks and Valencia scion continue growing in the nursery, with a plan for field planting in June 2024.Establish replicated field trials. No new trials were field planted this quarter, but two are planned for planting in the next quarter.Tree care in trials. Periodic care was applied in the 30 field trials to maintain tree health and productivity, and manage weeds. Two young rootstock trials are being grown with IPCs. One rootstock trial is being used for a comparison of tree performance of different rootstocks with and without OTC injection.2. Please state what work is anticipated for next quarter:For the coming quarter, work will focus on processing brix, acid, and color for about 5000 juice samples from rootstock trials in the 2023-24 season, continuing propagation of trees for future trials, collection of data on tree size and health in trials, and care of existing trees in trials. Two new Valencia rootstock trials with the advanced SuperSour selections are planned for field planting in the next quarter. Data analysis of tree performance in the 30 trials is underway, to evaluate SuperSour candidates for official release in 2025-26, and to compare performance among commercially available rootstocks. Cooperative work continues to evaluate USDA rootstocks for tolerance/resistance to sting nematode, citrus nematode, salinity, cold hardiness, nursery performance, and other traits. Work continues to coordinate with other laboratories in mapping of important rootstock traits that will facilitate more effective citrus breeding in the future.3. Please state budget status (underspend or overspend, and why):The budget is on schedule and spent out all second-year funds at the end of the second year of the project. Work is progressing as planned.