This project has two objectives: (i) Assess the performance of new grapefruit cultivars with certain rootstocks in the IR district; and (ii) Evaluate the influence of UFR and other recent rootstocks on grapefruit, navel, and mandarin in the IR in comparison to legacy/standard rootstocks. There are four trials: Trial 1) 18 grapefruit cultivars on three rootstocks; Trial 2) 32 rootstocks with `Ray Ruby’ grapefruit as the scion; Trial 3) 31 rootstocks with ‘Glenn F-56-11′ navel orange as the scion; and Trial 4) 31 rootstocks with `UF-950 mandarin as the scion.There are now 4,900 trees in the grove. The final 90 grapefruit trees on UFR-8 rootstock are growing slowly in the nursery and are expected to be planted in February or March 2022. In August 2021, leaf and soil samples were collected from each experimental plot to properly manage fertilizer requirements. Controlled-release, polycoated fertilizer was applied appropriately in early November 2021 based on lab results. All trees were treated biweekly with appropriate agrochemicals to manage canker, Asian citrus psyllid, mites, and citrus leafminers.Tree height, tree width in cardinal directions (E-W/N-S), and trunk diameter were measured on the three middle trees in each experimental plot in October 2021 to quantify canopy volume and tree size. Some scion/rootstock combinations are exhibiting significant differences in canopy volume. In Trial 1, `Pummelette UF-5-1-99-2′ grapefruit on US-942 is 5.6X larger (11.2 m3) than `US 1-83-179’ grapefruit hybrid on sour orange (2.0 m3). In Trial 2, grapefruit on UFR-15 is 2.6X larger (8.9 m3) than on 46×20-04-6 (3.4 m3). In Trial 3, navel orange on US-802 is 1.8X larger (5.3 m3) than on Willits, UFR-16, and UFR-1 (2.9 m3). In Trial 4, mandarin on US-942 is 2.6X larger (6.2 m3) than on 46×20-04-6 (2.4 m3). Many trees are developing vigorous canopies despite HLB symptoms. Results will be presented at the annual Florida Citrus Show in January 2022 in Fort Pierce, FL. Visual HLB symptoms are apparent on approximately 25% of the total tree canopy volume for most of the plots. However, trees look vigorous and maintain a bright green foliage. Leaf samples from Spring flush were collected in September 2021 and sent to Southern Gardens Labs for quantifying CLas titer. The ct values ranged 35-40 (CLas-free >32). Leafminer damage was substantial during the summer months but decreased recently with cooler temperatures. Nevertheless, tree growth has not been significantly adversely affected by these pests due the biweekly application of agrochemicals.Trees are bearing their first fruits, and we expect to collect this information in the first quarter of 2022, which will serve well to establish potential yields and marketability as well as HLB damage. Long-term evaluation is needed to identify the most promising scions and rootstocks to determine their profitability and capability of meeting grower and market needs.The Citrus Horticulture Lab organized the annual drive-through Millennium Grove Field Day on 14 October 2021 to showcase the results to growers and stakeholders. More than 50 attendees coming from local and neighboring counties (St. Lucie, Okeechobee, Polk) toured the grove, received an explanatory handout, and met with personnel involved in the project.