Descriptions are given for the most important Florida grapefruit cultivars which are listed below in alphabetical order. A summary of grapefruit cultivars characteristics can be found in Table 1.
'Burgundy' is a patented cultivar arising from 'Thompson'. This cultivar is commercially seedless and has a much deeper and more uniform red flesh color than either 'Redblush' or 'Thompson'. The red flesh color holds late into the season, as opposed to that of 'Redblush' and 'Thompson' which tend to fade as the season progresses. 'Burgundy' does not attain good eating quality until April-May or later and it was originally planted as a late-maturing type. Only a few hundred acres of 'Burgundy' have been planted and it is not likely that it will become a popular commercial cultivar due to the late date of maturity.
'Duncan' ( Plate 2) is the oldest grapefruit cultivar grown in Florida and is believed to have originated as a seedling about 1830 near Safety Harbor at the site of the original grapefruit planting established by Count Odette Phillipe. Many other selections of seedy, white-fleshed grapefruit have been made and cultivar names given them. However, virtually all seedy,
white-fleshed grapefruit are marketed as 'Duncan' since there are no major differences among these cultivars. 'Duncan' fruit are large, oblate, pale to light yellow in color, and may contain up to 60 seeds. The buff-colored flesh is tender, juicy and of excellent flavor. Its sections are firm and 'Duncan' is the standard of excellence for processing as grapefruit sections. Seediness precludes its use as a fresh-market fruit.
'Flame' grapefruit ( Plate 3) was selected from 'Henderson' (a Texas cultivar) seedlings planted in 1973 at the A. H. Whitmore Foundation Farm near Leesburg. Fruit are commercially seedless, with internal color almost as deep red as that of 'Star Ruby' and blush comparable with 'Ray Ruby' but less than 'Star Ruby'. Flesh color of 'Flame' is noticeably darker than 'Ray Ruby' throughout the harvest season. Preliminary data suggest good internal and external quality but no yield data are currently available for this cultivar. 'Flame' grapefruit is suggested for trial use in Florida.
'Foster' ( Plate 4), a limb sport of 'Walters', is the first pink-fleshed cultivar on record. However, its popularity was short lived due to the 1924 release of 'Thompson', a seedless pink-fleshed cultivar. Fruit are medium to large, very seedy and have a pink peel blush. 'Foster' has not been planted to any appreciable extent in Florida for many years.
'Marsh' ( Plate 5), also known as 'Marsh Seedless' and 'White Marsh', arose as a chance seedling planted near Lakeland about 1860. Soon after its introduction, 'Marsh' became the grapefruit cultivar most widely planted in Florida, and throughout the world, a status it has retained to this day. The medium-sized fruit are oblate to spherical with a medium-thin light yellow peel. The buff-colored flesh is juicy and of excellent quality, but sugar and acid levels may be slightly lower than 'Duncan'. Fruit contain 6 or fewer seeds making 'Marsh' particularly well-suited for fresh consumption. Fruit hold well on the tree but may acquire a bland flavor late in the season.
'Ray Ruby' ( Plate 6) was first observed growing in a Texas grove of 'Redblush' grapefruit. 'Ray Ruby' is comparable to 'Redblush' in many respects. Juice and seed content, flesh texture and maturity date are similar for these two cultivars. However, internal color holds better late in the season for 'Ray Ruby', and greater blush is usually noted for this cultivar than for 'Redblush'. Texas trials suggest that yields and growth characteristics are similar to 'Redblush'. However, no yield data are available for 'Ray Ruby' in Florida where it is recommended only for trial use.
'Redblush' ( Plate 7) and 'Ruby' are both believed to have originated as limb sports of 'Thompson' and are, for all practical purposes, indistinguishable and should be considered identical. 'Ruby' and 'Redblush' were discovered in separate Texas groves in 1929 and 1931, respectively. The name 'Redblush' is very descriptive of this fruit and has become the preferred cultivar name although 'Ruby', 'Ruby Red' and 'Red Marsh' are sometimes used. Fruit are very similar to 'Thompson' differing primarily in the intensity and distribution of red pigmentation in the fruit. Red flesh color is much deeper than for 'Thompson' and a crimson blush, not found in 'Thompson' often develops in the peel. A number of bud sports with red flesh color and peel blush have arisen over the years, but they are indistinguishable from the original mutation. Fruit are of excellent quality, although sugar and acid content may be slightly lower than 'Thompson'. Although fruit quality tends to increase through April, some fading of flesh color occurs late in the season. Seedlessness, high quality and excellent coloration of 'Redblush' have placed this cultivar in great demand.
'Star Ruby' ( Plate 8) originated from the seed of 'Hudson' (a seedy pink-fleshed cultivar), treated with gamma rays at Texas A&M University and was released in 1970. Short internodes, profuse branching and a compact habit of growth characterize this cultivar. The medium-sized, seedless fruit have exceptional red flesh color and a distinctively smooth, thin peel with a pronounced red blush. Sugar and acid content are higher than that of 'Redblush'. Flesh is firm, uniform in color, and of excellent quality. Furthermore, juice is deeply colored, even late in the season and may have potential for enhancing the color of pink grapefruit juice. However, 'Star Ruby' is more difficult to grow in Florida than most other grapefruit cultivars. Foliage is often chlorotic. Trees are easily damaged by some herbicides and are susceptible to foot rot. Propagation of 'Star Ruby' in Florida peaked during the 1984-85 season and has since declined, presumably because of cultural problems associated with this cultivar.
'Thompson' ( Plate 9), also known as 'Pink Marsh', arose as a limb sport of 'Marsh' near Oneco, Florida. In 1924, 'Thompson' was introduced by a local nursery and, being the first pigmented seedless grapefruit cultivar, became quite popular. However, other seedless cultivars with superior flesh and peel color were soon discovered and planted in favor of 'Thompson'. Fruit characteristics are essentially identical to 'Marsh' with the exception of the pink flesh color. Sugar and acid levels may be lower than 'Marsh', but not meaningfully so. Fruit hold well on the tree, but flesh color fades as the season progresses.
