| 0 | PI 539828 | 'SWINGLE' | Citrus sp. | Florida, United States | RIV | | | 1977 | DEVELOPED | 1907 | | | | | Cultivar | This is definitely Swingle. USDA-DCS GH 316. Origin FF-9-22-55 Leesburg USDA Foundation Farm, Florida...(WP Bitters, 12/02/1979) USDA Foundation Farm, Leesburg, Florida, Block 9, Row 22, Tree55. Is supposed to be clonal (budwood) source of CPB 4475. Per letter of J. Carpenter Feb. 8, 1974 to Carl Sierra, Calif. State Div. of Plant Industy. (RK Soost, 07/1985) It certainly appears that there was some concern about getting the correct bud source of 'Swingle' back in the 1970s. Note: Referenced letter of JBC to CDFA is not on file to present knowledge. There are currently three (apparently redundant) accessions of 'Swingle' maintained at the Repository: the current accession PI 539828/RCRC 3771, PI 539844/RCRC 3767, and PI 539824/RCRC 3341. Apparently PI 539844/RCRC 3767 and PI 539828/RCRC 3771 were received from the same source (USDCS) at slightly different times and were given different CRC numbers (which were assigned differently in the 1970s than they are now). It appears that PI 539844/RCRC 3767 was received about a year later than PI 539828/RCRC 3771 and was planted into the Citrus Variety Collection without any sort of indexing, or possibly it was indexed without receiving a VI number. In any case, it appears that PI 539844/RCRC 3767 and PI 539828/RCRC 3771 are the same genotype and derived from the same source and as such are definitely redundant. Although 'Swingle' was originally hybridized by Swingle in 1907, experimentation with it as a rootstock did not begin until about four decades later. Trials were planted in Florida by personnel from the Subtropical Horticulture Laboratory in Orlando and in Texas by USDA personnel including Bill Cooper, Ed Olson, Heinz Wutscher. To Heinz Wutscher must go much of the credit for developing 'Swingle' into the widely used rootstock that it is today. The early development work is summarized in the Release Notice, Hutchison (1974), Anonymous (1974), Wutscher (1979), Castle (1987), and Castle et al (1988, 1989). These sources summarize the superior attributes of 'Swingle' as being resistant to tristeza and Phytophthora foot rot, blight, cold, and citrus nematode. However, in some cases, trees budded onto 'Swingle' that were infected with 'severe' strains of exocortis or cachexia remained stunted and produced a bud union crease. 'Swingle' is moderatlely salt tolerant but is not adapted to heavy clay soils or calcareous soils. 'Swingle' was observed to be particularly well adapted for use with grapefruits and in some cases 'Lisbon'-type lemons. These attributes lead 'Swingle' to become the mostly highly utilized rootstock in Florida (Stover and Castle, 2003). However, as older trees on 'Swingle' became available to observe, some limitations became apparent (Castle and Stover, 2000; Stover and Castle, 2003; Castle and Stover, 2001). In addition to those noted above associated with soil conditions, trees on 'Swingle' were observed to decline decline on specific Flatwoods and Ridge soils and when Phytophthora was present in combination with Diaprepes; some apparent incompatibilities with specific scions also appeared. Nontheless, 'Swingle' is considered one of the 'standard' rootstocks to be considered for planting in many situations or trials. (RRK, 01/2008) | 1434764 | PI 539828 |
| 1 | PI 539678 | 'Sunki' | Citrus ×aurantium L. var. chrysocarpa (Hassk.) ined. | California, United States | RIV | | | 1956 | DEVELOPED | 1983 | | | | | | "The sunki, suenkat or sunkat of South China, which is the sour mandarin C. reticulata, var. austera) of Swingle's classification...is a medium-small, upright tree with distinctive pale-green leaves. The fruit is medium-small, oblate and markedly depressed at both ends, and with basal furrows. The rind is very thin, loose, and light yellowish-orange, with a smooth, shiny surface and prominent oil glands. The rind is strong and spicy with a distinctive aroma. The flavor is acid, the fruit never becoming edible. Seeds are medium-large, plump, polyembryonic, and have pale-green cotyledons. "C. sunki is considered to be native to China and is said to be a widely employed rootstock in China and Taiwan." (Hodgson, 1967, pp 525-526) "Differs from the sweet mandarin orange in having smaller fruits with intensely acid pulp. The type of this variety is the sour mandarin called sand#252;n kat in Cantonese, propagated from seed in the Swatow region of Kwantung, where it is commonly used as a rootstock for grafting. G.W. Groff in 1918, in a manuscript report covering his work on citrus done in China under Swingle's supervision for the former Bureau of Plant Industry of the U.S. Department of Agriculture, described the sand#252;n kat as follows: "'Fruits slightly depressed-globose, 2.9-3.3 cm long, 3.3-3.6 cm diam., with smooth, loose peel about 4 mm thick, capucine yellow (Ridgway, pl. 3) when ripe; oil glands small, round, far apart, fragrant; segments 9, easily separated; segment walls thin, tender, white; core 6-8 mm diam., soft; pulp deep chrom yellow (Ridgway, pl. 3), composed of small, short, pulp-vesicles, clinging together but irregularly arranged and easily broken; juice reddish yellow, very sour; seeds about 9, rounded at one end, pointed at the other, showing white parallel lines from base to tip; leaves lanceolate-elliptical, blades 6.8 X 2.5 cm, rather acutely cuneate at the base and narrowed to a blunt apex, with about 10 pairs of lateral veins; petioles nearly wingless.' "This variety is widely grown about Swatow, China, where it is used as a rootstock upon which to graft the Ponkan or mi-tong-kan ("honey pot orange") and other famous varieties widely exported from Swatow. "Probably some of the other sour mandarins called kat by the Cantonese are forms of this variety. Some of the so-called kat varieties with large fruits, which as they ripen may become sweet enough to eat, are probably hybrids between the variety austera and the sweet mandarin, C. reticulata, or the sweet orange, C. sinensis." (Swingle, 1943, p 415; Swingle and Reece, 1967, pp 381-382) A small sour mandarin. (EM Nauer, 03/1987) Sunki is widely used as a rootstock in China but has not had extensive evaluation in other areas. It is tolerant of tristeza and xyloporosis but susceptible to exocortis. Sunki is reported to be susceptible to Phytophthora but has survived well in some trials. It is also said to be tolerant of blight-like diseases in Brazil. Trees propagated on Sunki are reported to be highly salt tolerant, moderately cold hardy, and only slightly susceptible to chlorosis on calcareous soils. Trees on Sunki have been reported to be smaller than standard in China and Texas but large in Florida and California. Fruit yield and quality are at least equivalent to trees on sour orange or Cleopatra mandarin. Sunki is polyembryonic but has a higher proportion of zygotic seedlings than many other rootstocks. (Summarized from Wutscher, 1979, p 251; Castle, 1987, pp 373-374; Castle et al, 1993, p 25) This is the "standard" accession of 'Sunki'. A recently received selection is RRUT 444. (RR Krueger, 07/09/2009) | 1434614 | PI 539678 |