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World of CitrusWorld of CitrusDuncan Grapefruit
Givaudan Citrus Variety Collection at UCR
https://citrusvariety.ucr.edu/crc3832 (opens in a new tab)
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J.V. da Graça, E.S. Louzada, and J.W. Sauls · Proceedings of the International Society of Citriculture · 2004
This proceedings paper reports Duncan as a seedy, white-fleshed grapefruit from a Florida seedling planted circa 1830 and named in 1892; the authors’ historical account traces later pigmented varieties to Duncan (p. 369). This is historical synthesis, not new genetic evidence.
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Robert E. Rouse, Heinz K. Wutscher, and Charles O. Youtsey · Subtropical Plant Science · 2001
Secondary historical account. Printed p. 1 reports Duncan as white-fleshed, with 30–50 seeds per fruit, and the grapefruit quality standard; it dates naming to 1892 and the seedling to about 1830.
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Robert Willard Hodgson · University of California, Division of Agricultural Sciences · 1967
Robert Willard Hodgson’s Chapter 4, “Horticultural Varieties of Citrus,” pp. 431–591. The Duncan grapefruit subsection reports that Cooper, Reece and Furr (1962) established that the Bowen variety used in some early Florida citrus breeding was Duncan. This is Hodgson’s secondary report, not a direct citation to the 1962 study. The passage does not identify all material ever called Bowen or Bowman.
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Slow Food Foundation
https://www.fondazioneslowfood.com/en/ark-of-taste-slow-food/duncan-grapefruit/ (opens in a new tab)
Secondary Ark of Taste profile. It attributes the Duncan seedling to about 1830 near Safety Harbor and naming/introduction to 1892. Describes white flesh, many seeds (up to 60 in a fruit), smooth pale-yellow medium-thick rind, and November–May ripening depending on location, without a reported trial or sampling method. It states Duncan × Dancy origin for Minneola and describes Marsh as Duncan offspring; these are profile claims, not verified pedigrees.
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A.C. Saville, A. Krings, T. Kahn, M.D. Trice, and A.J. Redford · USDA APHIS PPQ CPHST; North Carolina State University · 2011
https://idtools.org/citrus_id/index.cfm?packageID=1179&entityID=8489 (opens in a new tab)
Citrus ID, Edition 2 (October 2011); Duncan entry. The compilation cites Hodgson (1967) and Chiefland Budwood Facility (2010). The facility note names clones F-56-33/F-57-19 and reports 30–70 seeds, clustered fruit, and November–May season; no sample method is supplied. Hodgson’s quoted fruit/tree description and cold-resistance reputation are secondary claims, not measurements from this entry.
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Growing Fruit
https://growingfruit.org/t/duncan-grapefruit/10130 (opens in a new tab)
Community discussion with separate dated posts: Steve333 (25 Mar 2017) recalls shipped Florida fruit as yellow-fleshed, very sweet, and seedy; fruitility (27 Mar 2017) reports a young Duncan tree near Houston died after an unquantified cold blast; Spin (4 Oct 2019) reports his wife tasted a slice from a neighbor’s fruit and describes it as juicy and non-bitter. Spin’s own recently planted tree was not the tasted specimen. No trial conditions or measurements are reported.
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mrtexas · Citrus Growers Forum (read-only archive) · 2013-03-22
http://citrusgrowersstatic.chez.com/web/viewtopic87a6.php (opens in a new tab)
Grower mrtexas reports tasting seedy Duncan fruit grown in southeast Texas. He contrasts fruit tasted roughly a month earlier as somewhat tart with a later tasting he compares to remembered late-season Duncan fruit from Bradenton, Florida; the timing is recollected and subjective. He also reports topworking his golden grapefruit tree with Duncan budwood from a seedling and bearing source and getting three fruit that year from the seedling-source wood. No measured chemistry or controlled comparison.
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Jeff Klinkenberg · Times newspaper feature (reproduced in Citrus Growers Forum archive) · 2009-01-02
http://citrusgrowersstatic.chez.com/web/viewtopic28a1.php (opens in a new tab)
Forum topic 28a1 reproduces a newspaper feature credited to Jeff Klinkenberg, Times Staff Writer, dated Jan. 2, 2009. The article profiles Bill Burchenal’s Odessa-area grove and reports that he had recently planted 150 Duncan trees within a 15,000-tree grove. Journalistic profile, not a trial.
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u/Ok_Competition_447 · Reddit, r/Tiki
https://www.reddit.com/r/Tiki/comments/115v70d/duncan_white_grapefruit/ (opens in a new tab)
Poster reports taking a grapefruit from a Savannah residence; homeowner identified the backyard tree as Duncan. The poster reports saving seeds and getting a few sprouts, but gives no count or method. White grapefruit preference for cocktails is personal opinion. Cultivar identity is homeowner-reported, not independently verified; page displayed only “4y ago,” with no exact date.
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D-Grower · The Tropical Fruit Forum · 2019-12-26
https://www.tropicalfruitforum.com/index.php?topic=35799.0 (opens in a new tab)
Community topic started by D-Grower on 26 Dec. 2019, with later posts by mikkel (5 Feb. 2020) and D-Grower (7 Feb. 2020). D-Grower offers Florida seeds and asserts seed-grown fruiting in about five years if conditions suit and cold hardiness to zone 8, without defining a temperature, exposure, or method; this is a grower/seller statement. mikkel reports tasting one first Duncan fruit, a separate informal account. D-Grower’s report of similar fruit across seed-grown generations is personal observation and does not verify tree identity.
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Terra Mater Gardens · YouTube
https://www.youtube.com/watch?v=oiJNOu4ZHZA (opens in a new tab)
Summary from transcript: English auto-generated captions exported from the 2:05 video. Narration describes Duncan fruit as nearly round, with smooth light-yellow rind and very pale-yellow, juicy, seedy flesh, and describes a large, spreading, vigorous tree. No observation specimen, location, date, or measurement method is given. General cultivation advice is not a documented trial. The narration’s historical account is uncited and conflates cultivar origin with grapefruit history; do not rely on it to replace cited historical accounts.
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THE URBAN HILLBILLY · YouTube · 2022-01-10
https://www.youtube.com/watch?v=U7tX_hWZFKk (opens in a new tab)
Summary from transcript: English auto-generated captions from the 7:10 video. Informal tasting of fruit presented as Duncan; the narrator contrasts it with a baseball-sized fruit from a prior video but says that earlier fruit had been picked up from the ground, so specimen continuity is uncertain. The transcript reports partial seed counts and an estimate of 40–50 seeds in one grapefruit, plus subjective juiciness. A “maybe a five” sugar-content comment has no defined scale and is not a validated measurement. No location, maturity date, or test method is stated.
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Ana Paula de Moraes; Walter dos Santos Soares Filho; Marcelo Guerra · Springer · 2007
https://pubmed.ncbi.nlm.nih.gov/17295131/ (opens in a new tab)
Chromosome Research 15(1), 115–121 (2007); DOI 10.1007/s10577-006-1101-2. The PubMed abstract reports sequential CMA/DAPI staining and rDNA-FISH for six grapefruit, two pummelos and one tangelo. It places Duncan Grapefruit in the group reported to have two CMA-positive C-type and six D-type chromosomes, with four reported 45S rDNA sites. Two chromosomes carried 5S rDNA across the accessions. Full text was not available in the inspected publisher view. These marker patterns are not a ploidy determination, full chromosome count, shared cultivar identity or proof of this cultivar's parentage.
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Edward O. Olson and G. H. Godfrey · Rio Grande Valley Horticultural Club · 1953
http://www.subplantsci.org/wp-content/uploads/2016/02/v07-1953.pdf (opens in a new tab)
Table 2, printed p. 28, reports counts for seedlings in Substation 15 plots inoculated in 1950: cotton-root-rot deaths in 1951 and 1952, and seedlings alive in September 1952. Counts are not percentages; the table gives no per-row denominator. The paper cautions that freeze injury, other diseases, and planting-date differences complicated comparisons.
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F. E. Gardner and G. E. Horanic · Proceedings of the Florida State Horticultural Society · 1959-06-13
https://journals.flvc.org/fshs/article/download/101309/97253/130008 (opens in a new tab)
Table 1, printed p. 83, reports adjusted and unadjusted cold-injury ratings and trunk circumference for named rootstocks under Valencia orange tops. The 10-year-old planting was at Weirsdale, Florida; injury followed winter 1957–58 freezes and ratings were made June 18, 1958. The study-specific ratings are comparative rootstock results, not traits of the rootstock variety as a scion or a temperature threshold.
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