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World of CitrusWorld of CitrusUS SuperSour 4
Kim D. Bowman · HortScience / American Society for Horticultural Science · 2023-11-28
https://doi.org/10.21273/HORTSCI17466-23 (opens in a new tab)
Table 1 identifies SS4 parentage as a Florida Hirado seedling × Cleopatra and lists release year 2023. The article gives SS2–SS5 a collective 2000–2006 cross range, not an individual SS4 cross year. Its 2014 Picos/St. Lucie Valencia trial includes SS4; trial yields are Valencia scion results, not fruit or yield intrinsic to the rootstock.
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Kim Bowman · Citrus Research and Development Foundation · 2024-05-15
https://citrusrdf.org/fmuploads/2024-04_21-008_Bowman_PR.pdf (opens in a new tab)
Page 1, Objective 1, “Release of new rootstocks,” states that US SuperSour 4 and US SuperSour 5 were “released in September 2023” and propagated for upcoming demonstration plantings and field trials. This is the project report’s release-status account; it supports September 2023 at month precision, with no day stated, not a specific trial outcome.
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Caroline Tardivo; Sailindra Patel; Kim D. Bowman; Ute Albrecht · HortScience / American Society for Horticultural Science · 2025-05-16
https://doi.org/10.21273/HORTSCI18529-25 (opens in a new tab)
The abstract and Table 1 (p. 933) identify US-1688 as SS4. Table 3 (p. 935) reports 54 seeds per fruit from open-pollinated SS4 source-tree fruit at the USDA A.H. Whitmore Foundation Farm, Leesburg, Florida (nine fruit per rootstock). Table 4 reports seed germination 91%, seedling survival 96%, visual similarity 89% (50 seedlings), and SSR true-to-type 0% (24 tested seedlings). Table 3's printed 8.0 cm length and 3.0 cm circumference are omitted from observation claims because the dimensions appear inconsistent. A separate Fort Pierce trial reports 34.2 kg Valencia scion fruit/tree for SS4 in 2022–23; same-site/scion/planting context may overlap Bowman 2023 and is not an independent replicate. US-1709/SS5 is not tested.
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Ariel Singerman; Kim Bowman; Danelle Seymour · Citrus Industry (sourced from UF/IFAS Citrus Magazine) · 2026-01-07
https://citrusindustry.net/2026/01/07/study-shows-performance-new-rootstocks/ (opens in a new tab)
The article analyzes Valencia scions in the 2014 USDA Picos Farm, Fort Pierce trial (640 trees/ha; 50 rootstocks). It reports US SuperSour 4 among the two highest-performing rootstocks, with 638 lb solids/acre and a $2,307/acre cumulative revenue difference versus sour orange in 2022 dollars at 10% interest. The reported six-season analysis concerns the grafted Valencia crop and the same 2014 Picos cohort discussed in Bowman 2023, not a separate trial; the article's relative trial years are not mapped to calendar years.
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