Poncirus trifoliata (Trifoliate orange) and its hybrids with the genus Citrus
Poncirus trifoliata is closely related to the genus Citrus and it is monotypic just like the genus Clymenia. Even despite this, it still belongs among very important genera used for cultivation; its only representative is Poncirus trifoliata (L.) RAF. Poncirus trofoliata or also Trifoliate Orange has been cultivated in China for several thousands of years without any significant mutations and even nowadays it still remains the only representative of its genus, even though there are many variations and forms. These different forms vary in the size of their fruit (var. microcarpa), leaves and flowers, spikes, leaf patterns (golden dotted pattern on the leaves (var. punetata)) or grotesquely twisted branches (var. monstrosa). There is also a variety without any spikes and several significant varieties, of which some are described below:
Very ornamental dwarf variety known as the ‚Flying dragon is a mutation of the original Poncirus form originating in Japan. It’s distinctive with its tiny leaves organized into three-leaved form (trifoliate) joined with the plant by almost linear petioles. The plant is deciduous and has twisted, snake shaped branches decorated with curved spines. It’s supposedly hardy to -25°C (-13°F).
The fruit is small (4‑5 cm), either ball-shaped or flattened. Its rind is very thin, yellow with a few ridges. The pulp is yellow in color, soft with resin-like aroma. The fruit has 6‑8 segments and lots of seeds.
Flying dragon is idle for growing in pots and as a rootstock for tangerines, because it significantly lowers the mature height and crown size of the grafted plant, yet allows the plant to fruit early in the fourth season. Considering, that the yield calculated for one tree is higher with the classical form of Poncirus, the yield calculated for the crown size is higher with the Flying dragon variety. The fruit quality is excellent, acidic flavor is not passed on to the grafted plant and the fruit has better color. This variety is used as a rootstock in California for high density planting of lemon.
The clone ‘Monstrosa’ has twisted branches with long curved spines and very small leaves. In the past, it was labeled as C. Trifoliata var. monstrosa T. Ito. The clone ‘Hiryu’ can have purple young shoots and the fruit has a warty-like tip with a ridge at the basis.
It was bred from 'Rubidoux'. This deciduous tree grows to medium height with very wide branches and trifoliate leaves. Its flowers are small and so is the flat oily fruit (4cm in diameter), which has a thin yellow rind (oplodí žluté, hrubé, tenké...). The pulp, divided into 6-8 segments, is amber yellow with resin-like aroma and full of seeds. The clone 'Rich 7-5' has bigger flowers, smaller, more spherical fruit (3cm) with medium thick dark yellow rind decorated with several ridges. Its pulp is very soft, yellow and full of seeds.
It was bred in 1920 in a research center of the University of California in Riverside. It was named after the hill MountRubidoux, close to which the research station is localized. The tree is deciduous and grows to a medium height. It also has wide branches and egg-shaped trifoliate leaves. It is said to be hardy to -25°C. The fruit is flat, quite small (3,5-4,5 cm in diameter), weighs about 30g and has thicker yellow rind (3 mm). The pulp is amber yellow and very soft. It is divided into 7-8 segments and each segment is full of seeds. This variety is mainly used as a rootstock in California.
The fruit is smaller (usually to 5cm in diameter), usually yellow or with slight orange touch. Some poncirus varieties bare inedible fruit, other bear edible fruits with only small amount of seeds and tasty pulp with resin-like aroma. Some cultivars have little or no pulp due to many seeds (many times over 40). However it is for this seeds, that this plant is so widely cultivated.
Poncirus is very resistant to diseases (except exocortis), root fungus and also many pests. Poncirus is not as susceptible to mycorrhiza as other citruses.
It requires well drained and airy soil with lots of organic nutrients, for the best growth it requires sandy clay soils. It can also grow fairly well in heavier and wet soils, but it dislikes dry, settled, shallow, exceptionally rocky, sandy soils or soils with too high underground water level. Poncirus is very susceptible to calcium (up to 10% of active calcium), soil salinization and chlorides. The ideal for our country is pH 6,5 and lesser.
Poncirus has quite long vegetation period, that’s why the best results were observed in viticulture areas or protected localities at southern walls etc. In other areas is the cultivation outside almost out of question, because of the low amount of vegetation warmth. In the Czech lowlands is this amount of warmth in the period from 1.April to 7.October more than 2800°C. In areas more than 400 meters above the sea level is this amount about 2500-2600°C. This amount of vegetation warmth isn’t sufficient for annual shoots to mature. That’s why these plants are after the winter heavily frostbitten and start shooting the next spring from the roots. Matured annual shoots with finished vegetation period can withstand the frosts even below -20°C without any frostbite. The damaged trunk is usually after the winter fissured, becomes black and dries out.
Citruses grafted on Poncirus trifoliata start fruiting early and are characteristic with good quality of fruit and high yields. The grafted citruses also have improved hardiness, but during the winter, they need to be kept dormant in temperatures best ranging 0°C to 8°C. It’s an unusual case that evergreen plants prosper during vegetation grafted on a deciduous rootstock. Poncirus is also the main rootstock for Unshiu tangerines, however older plants show some differences in growth of rootstock and grafted citrus, because the rootstock’s trunk grows more vigorously and is thicker, than the grafted one. Trifoliate Orange is compatible with almost 95% of citruses. It significantly alters the grafted citruses, the plant becomes a dwarf, grafted plants have healthy and good growth and the rootstock also has varying influence on the quality of fruit and its nutrition value. Almost any influence of the rootstock on the grafted plant is positive.
As a deciduous plant, it usually becomes dormant quite early and so it also speeds up maturation of younger shoots of grafted citruses and thus improves the resistance of the whole plant to cold. That’s why it’s always wise to choose the Poncirus varieties with the shortest vegetation period possible. Poncirus rootstocks also improve the immunity and resistance to diseases and speeds up fruit ripening. If the citrus with Poncirus as a rootstock is kept in a flat, it should be put into a cold room with the temperatures of about 8°C, otherwise the leaves of grafted plants will fall of the tree and the plant recovers only scarcely. Poncirus has also proven useful as a breeding and crossing plant. Seedlings are varying in quality and aren’t similar after sowing.
Trifoliate leaves with narrow petiole fall off the tree before winter. It’s therefore very interesting, that the young Trifoliate Orange often doesn’t get rid of the leaves for winter. This interesting behavior occurs before it reaches the fruiting age. Only then, after the first fruiting, the plants begin to cast leaves for winter, because all the plant’s nutrition is put into the ripening fruit.
In conclusion, Poncirus trifoliata is a unique deciduous shrub or small tree decorated by many spines. It can easily be crossed with other plants from the genus Citrus and with this genus it has also created many remarkable hybrids (citrange, citrangequat, citrandarin, citrumelo, and many more in a wide scale of varieties).
Citrange – it is a cross between C.sinensis (L.) Osbeck x Poncirus trifoliata (L.) Raf. Citranges are resistant to almost every disease, with an exception of winter overwatering and are hardy to -15°C. One of their main characteristics is also great ability to adapt; they enhance the fruiting and the fruit’s quality. Most of the citranges are vigorously growing with great resistance to diseases and vinegar worms.
It’s a hybrid of a sweet orange 'Ruby' and Poncirus 'CRC 2552', which was bred in 1951 inCalifornia. The tree is deciduous, medium in height with wide branches and trifoliate leaves. Its fruit is medium to smaller (about 5 cm in diameter), flat, with a small neck-like outgrowth. The rind is orange, thin and smooth with essential oils. The fruit’s pulp is green, not too soft with resin-like aroma and divided into 8 segments with very little or no seeds. Even though it is used as a rootstock.
Hybrid of sweet orange 'Ruby' and poncirus 'CRC 2552' originating from California, bred in 1951 and released to public in 1987. The tree itself is deciduous and medium high with very wide branches covered with small trifoliate leaves. It is resistant to nematodes (roundworms) and also to weaker cold. The fruit is smaller to medium (5 - 6,5 cm), spherical with an average weight of 120 g. The rind is yellow, very thick and tough with essential oils. The pulp is amber yellow, not too soft with resin-like aroma and divided into 11 – 12 segments, totaling 10 seeds a fruit. It seems to be a promising rootstock, mainly used for navel oranges in California; the quality of the fruit is the same as with the rootstock 'Carrizo'.
It’s a hybrid of sweet navel orange Washington and poncirus CPB 4-5019, bred in 1909 by E.M.Savage in Carrizo Springs, Texas, finally named in 1938. It’s almost undistinguishable from the variety ‘Troyer’ and even has the same origin. It gained popularity in Florida and already beats the ‘Troyer’. ‘Carrizo’ was bred as a zygotic seedling, the difference between Troyer and Carrizo is in the resistance to the phytophora and Radolphus similis. Furthermore it is tolerant of viral diseases, tristesa, root rotting and xyloporosis.The tree is erect with wide branches and trifoliate leaves in the shape of egg. But its root system is shallow. Carrizo is also fairly cold tolerant and passes this characteristic on the grafted citruses. The fruit is small (about 4cm), ball-shaped, with a tough, thick orange rind. Carrizo fruit’s pulp is very soft and light orange with resin-like aroma. It is divided into 10 segments that include very little seeds.
Carrizo belongs to very popular rootstocks, but there’s a confirmed incompatibility with the lemon variety ‘Eureka’, orange ‘Roble’ and in Florida with tangor ‘Murcott’.
Hybrid of sweet orange 'Ruby' and poncirus, bred in 1913 by Dr. W. T. Swingle in Florida. The tree is deciduous and medium to high, with wide branches decorated by thorns that are however absent on branches carrying fruit. Leaves are mostly trifoliate.
It requires overwintering in a cold and is supposedly hardy to -15°C. The fruit is medium or small, about 5 cm long in diameter, slightly flattened and similar to the tangerines. Sometime’s there’s also a small navel in the fruit. With the soft, smooth or slightly pebbled (similar as poncirus) dark orange rind is this citrange better colored than the variety 'Coleman'. Its pulp is green to amber yellow, very soft, acidic and slightly bitter at the same time with resin aroma. There are a total of 10-12 segments and a very little seeds. This citrange is also used as a rootstock.
This hybrid of sweet orange ‘Ruby’ and Poncirus was bred in 1913 by Dr. W. T. Swingle in Florida and took name after an American head of department of agriculture J. Sterling Morton.
This citrange is medium in height, has shorter, not too wide branches with thorns, almost evergreen tree. Its leaves are dark green, trifoliate and simple on the same branch and much larger than those of Poncirus. Both the blossoms and buds are white and big (6 cm) and smell really well. The fruit is medium in size (6,5 - 7 cm in diameter), the largest fruit grows to the size of 7,5 cm in diameter, weighs 450 g and has a spherical shape, slightly flattened with a calyx. Morton’s rind is orange, thinner and not very tough, slightly pebbled and easier to peel with essential oils. The pulp is between yellow and orange, very soft, juicy and usually acidic with wonderful aroma. There usually aren’t any seeds inside the fruit. The membranes among 10 - 13 segments are slightly bitter. The fruit resembles oranges in size, yet taste like grapefruits. Usually, it ripens in the November. Morton’s fruit is used for jams and is undoubtedly the tastiest citrange fruit.
It also is suitable as a good rootstock, not well known though, and is considerably hardy. In hard frosts of -15°C only 8% of all the young shoots were frostbitten. The name ‘Morton’ is sometimes used to refer to a new cultivar, but it isn’t recognized, therefore this name is used only as a synonymic name.
It’s a very productive, well growing shrub, quite cold tolerant and very attractive and decorative. Rusk is evergreen and semi-deciduous very compact and wide tree, growing to medium heights, with trifoliate leaves and thorns. It was bred in Florida in 1897 by Dr. W. T. Swingle and Dr. H. J. Webber by crossing the sweet orange 'Ruby' and Poncirus, put into the fields in 1905. It’s named in honor of the first USA head of the department of agriculture, M. Rusk. This citrange is very hardy, supposedly to -15°C and is told to be also hardy enough to grow naturally in Czech gardens.
Its flowers and buds are white, bigger than oranges and aromatic. The fruit is however small (3,5-4,5 cm), flat with over falling basis and weak, pebbled, bitter, red to orange rind. Rusk’s pulp is dark orange, very tender and soft, juicy, but also bitter and aromatic. The inner part of the fruit is divided into 10-11 segments and has in average 4-5 seeds. Of all the citranges, this is the most yielding one. Its fruit resembles oranges the most of all citranges as well and are tasty to eat. The juice contained in juice sacks is acidic and is used along with the juices of other citruses in beverages. This citrange is rarely used as a rootstock, mainly because of a very low amount of seeds contained in the fruit.
Hybrid of a sweet orange 'Ruby' and Poncirus, bred in 1913 by Dr. W. T. Swingle in Florida. Evergreen and partially deciduous robust shrub with thorns resistant to frosts of -13°C. Rustic has dark green trifoliate leaves, larger than those of Poncirus, and dense crown. The rind is pebbled and the pulp green to yellow, acidic and bitter at the same time with lesser quality than other citranges. It usually has about 24 seeds a fruit, rarely none at all. Rustic is mainly grown for its ornamental value and is excellent rootstock for tangerines and oranges.
It’s a hybrid of sweet orange 'Washington' and Poncirus 'CRC 252' bred in 1909 by E. M. Savage in California, named in 1934 after A. M. Troyer, on whose field it fruited for the first time. Soon after that it became very popular (not in Florida) as an important rootstock just as it was a popular variety for growing. It took popularity from a very similar citrange - 'Carrizo', but nowadays Carrizo takes this popularity back (with an exception of Israel and Australia).
This deciduous tree is erect, more vigorous than Poncirus with lots of thorns on the branches and its leaves are dark green, mostly trifoliate and usually egg shaped. It is said to be hardy to -10°C, but it’s sensitive to high amount of calcium in the soil, salinization of the soil and exocortis. It is fairly resistant to phytoftora, but tolerant of viral diseases, tristesa, root rotting but not nematodes. Regular Zinc and Mangan additives are necessary,
The fruit has different shapes, they are small to medium in size (5,5 6- cm) with average weight 90 - 100g. Its shape is almost spherical; the rind is dark orange, smooth, sometimes even pebbled, very aromatic and not very thick. The pulp is yellow, juicy, but extremely acidic and slightly bitter, some fruits are even edible. There’s also resin aroma and the fruit is divided into 9-10 segments with up to 30 seeds, some of them partially undeveloped. It ripens in November or December. The seedlings are from 95 % nuclear and are an excellent rootstock for oranges and tangerines. It is also possible to graft grapefruits successfully as well, but it doesn’t accept grafting with the lemon 'Eureka'. Citruses grafted in Troyer have quality fruits, early ripening and good yields.
Citrumelo – is a cross of C.paradisi Macf. x Poncirus trifoliata (L.) Raf. Citrumelo is semi-vigorous in growth and very adaptive. Citruses grafted on citrumelo start to fruit somewhat later than on citranges, but it’s a very perspective rootstock, aspiring to be the best rootstock. It’s resistant to exocortis, influences the fruit quality only positively and in the latter years offers extremely high yields of fruits. Frost hardiness of the citrumelo is fairly high, it’s said to withstand the frosts of -15°C.
As the name suggests, this citrumelo was bred in Batumi at the Black Sea in Russia. The flowers are pink and resemble the Poncirus flowers with its shape. The leaves are trifoliate.
It’s a hybrid of grapefruit 'Duncan' and Poncirus bred in 1907 inFlorida by Dr. Walter Tennyson Swingle (the citrumelo carries his name in honor of his work) that was officially released only in 1974.
This deciduous tree is medium high with many wide branches and covered with normal sized trifoliate leaves. Its yields are very high, but the tree is less hardy, than the citranges. However some sources state that the hardiness of this particular citrumelo could be somewhere close to -15°C. Citrumelo ‘Swingle 4475’ is not sensitive on tristesa, exocrtis, xyloporosis, root rotting or nematodes.It stands well to overwatering, but dislikes too high soil salinization and high soil pH.
The fruit is medium sized (6,5-7,5 cm) with average weight 120 g. Its shape is elliptic or similar to that of pears; it has a ridge at the base. The rind is dark yellow, slightly pebbled, rough and about 9-10 mm thick. The pulp is amber yellow to light orange with soft, juicy and acidic taste and resin aroma. Each fruit has approximately 9-10 segments and few seeds.
It is an exceptionally good rootstock for grapefruit, that’s why it was spread so fast in the past. Grafted citruses are fruiting as well and with such a quality, as if they were grafted on ‘Troyer’, ‘Carrizo’ or Citrus aurantium. Slight difference is in ripening of the fruit, when the citruses grafted on ‘Swingle 4475’ start getting the right ripe color later, than with other rootstocks. The orange variety 'Valencia' reaches only smaller heights and has smaller fruit than on the other rootstocks, another incompatibility is said to be with the tangor 'Murcott' and orange variety 'Roble'. Also the lemon graft of variety ‘Eureka’ doesn’t grow well. Regarding the grapefruit and shedok, fruit quality of grafted citruses is excellent. This citrumelo is not adviced for tangerines and their hybrids because of the incompatibility. It isn’t popular rootstock in Mediterranean or Israel.
It’s a hybrid of grapefruit 'Duncan' and Poncirus bred in 1907 inFlorida by Dr. Walter Tennyson Swingle (the citrumelo carries his name in honor of his work) that was officially released only in 1974.
This deciduous tree is medium high with many wide branches and covered with normal sized trifoliate leaves. Its yields are very high, but the tree is less hardy, than the citranges. However some sources state that the hardiness of this particular citrumelo could be somewhere close to -15°C. Citrumelo ‘Swingle 4475’ is not sensitive on tristesa, exocrtis, xyloporosis, root rotting or nematodes.It stands well to overwatering, but dislikes too high soil salinization and high soil pH.
The fruit is medium sized (6,5-7,5 cm) with average weight 120 g. Its shape is elliptic or similar to that of pears; it has a ridge at the base. The rind is dark yellow, slightly pebbled, rough and about 9-10 mm thick. The pulp is amber yellow to light orange with soft, juicy and acidic taste and resin aroma. Each fruit has approximately 9-10 segments and few seeds.
It is an exceptionally good rootstock for grapefruit, that’s why it was spread so fast in the past. Grafted citruses are fruiting as well and with such a quality, as if they were grafted on ‘Troyer’, ‘Carrizo’ or Citrus aurantium. Slight difference is in ripening of the fruit, when the citruses grafted on ‘Swingle 4475’ start getting the right ripe color later, than with other rootstocks. The orange variety 'Valencia' reaches only smaller heights and has smaller fruit than on the other rootstocks, another incompatibility is said to be with the tangor 'Murcott' and orange variety 'Roble'. Also the lemon graft of variety ‘Eureka’ doesn’t grow well. Regarding the grapefruit and shedok, fruit quality of grafted citruses is excellent. This citrumelo is not adviced for tangerines and their hybrids because of the incompatibility. It isn’t popular rootstock in Mediterranean or Israel.
Citremon – is a cross of C. limon (L.) Burm. f. x Poncirus trifoliata (L.) Raf. Citremon is used as a rootstock in a few citrus growing localities. The frost tolerance of citremon is somewhere between -10 to -15°C, but it strongly varies with different soil types.
Citremon ‘Kovac’ is a high, very vigorous deciduous tree with spherical crown and trifoliate leaves. Its fruit is medium sized (5,5-7 cm),pear shaped with a ridge at the base. The rind is dark orange and not very thick and the pulp is amber yellow, soft with resin aroma. There are 8-9 segments and few seeds.
This deciduous tree is very high and vigorous with a spherical crown and trifoliate leaves. The fruit is medium sized (5,5-7 cm) and has a pear shape with a ridge at the base. The rind is dark orange and not too thick. Its pulp is very soft, amber yellow and has a resin aroma. There usually are 8-9 segments and a bunch of seeds.
Citrandarin – is a hybrid of C.reticulata Blanco x Poncirus trifoliáta (L.) raf. Citrandarin is very perspective hybrid with very tasty fruits ideal for growing in areas with viticulture. Its hardiness is somewhere between -15°C to -20°C.
Presumably a Czech variety, its branches are twisted like in the case of Flying Dragon and the leaves and blossoms are small. This varieties frost hardiness is supposed to be -15 to -20°C. It grows twisted and is overhanging, therefore it’s difficult to use for grafting.
Newly bred variety, the tests haven’t been finalized yet. It is a cross of tangerine variety 'Changsha' and Poncirus. It grows well and fast, has only simple leaves and is significantly hardier than the citranges 'Rusk' and 'Morton'. Its flowers are small, comparable to those of tangerines. B. Voss says about 15 clones labeled HRS and a capital letter, of which the clone 'HRS-899 J' is supposedly hardy to -15°C and the clone 'US 899 F' has much more vigorous growth.Its leaves mono-, di- and trifoliate and it’s a little bit hardier.
Newly bred variety, the tests haven’t been finalized yet. It is a cross of tangerine variety 'Changsha' and Poncirus. It grows well and fast, has only simple leaves and is significantly hardier than the citranges 'Rusk' and 'Morton'. Its flowers are small, comparable to those of tangerines. B. Voss says about 15 clones labeled HRS and a capital letter, of which the clone 'HRS-899 J' is supposedly hardy to -15°C and the clone 'US 899 F' has much more vigorous growth.Its leaves mono-, di- and trifoliate and it’s a little bit hardier.
It’s a hybrid of tangerine variety 'Cleopatra' and Poncirus that originates in The Republic of South Africa. This tree is very wide growing to medium hights. It is a deciduous tree with trifoliate leaves that is being used mainly as a rootstock.
Citradia – is a cross of C. aurantium L. x Poncirus trifoliáta (L.) Raf. Citradia is quite badly widespread when compared to citranges and citrumelos, but it also stands well behind in characteristics. It’s cold hardiness is about -10°C.
This deciduous tree is quite vigorous with a spherical crown and trifoliate leaves. Its fruit is small or medium (3,5-6,5 cm) and the fruit’s rind is very strong, dark orange and full of essential oils. The pulp is orange, very soft with resin aroma and 6-10 segments with only very little seeds. It’s mostly used as a rootstock.
Trifeola -
hybrid, cross of tangelo Mineola x Poncirus trifoliata
This is a cross of Shaddock 'African' and Poncirus 'Rubidoux'. Its fruit is medium in size (7 - 8 cm) and weigh 220 - 230 g in average. The rind is yellow to orange quite thick; the pulp has approximately 15 seeds.
Another very interesting group of citruses are hybrids of all the varieties above crossed again with either genus Citrus (mostly C. sinensis, Fortunella) or again with Poncirus trifoliata. Varieties that are a result of these crosses have fairly good cold hardiness and their fruit has very good quality. In most of these cases the resulting varieties are idle for growing in areas with viticulture with occasional frost protection. These varieties are hardy from -8 to -18°C.
Citrangequat -
hybrid, cross of Cumquat and Citrange
It was bred in USA, in 1909 as a cross of oval cumquat F. margarita (Lour.) Swingle and citrange. It has the same origin as 'Telfair' and fruited for the first time in Thomasvill. Considering the size of the fully edible fruit, it’s no wonder, that it has been gaining popularity. Of all the citrangequats, this is the mist yielding variety.
This evergreen tree is very robust and erect with many thorns. Its leaves have many different shapes, most of them are trifoliate, but there are also many simple leaves and the petiole is quite narrow. The fruit have the shape and size of chicken egg (3-5 cm), sometimes more spherical, sometimes more flattened. They usually are in such amounts, that the branches bend towards the ground. This citrangequat’s rind is slightly wavy and very thin. The pulp is very juicy, acidic before ripening and sweet after ripening. There’s only very little seeds in the fruit (2-6).
Thomasvill is considerably hardy (up to -12°C), it can be grown in the ground with adequate protection, but for our region it still remains the best choice for cold greenhouses. Thomasvill blossoms again after the late spring frosts. It is also used as a rootstock for cold overwintering and growing dwarf varieties.
It was bred by crossing cumquat 'Nagami' and citrange 'Rusk' and it originates in USA. It fruited for the first time in Sinton, Texas and was described by Dr. W. T. Swinglem in 1923. This variety is very attractive, medium high in maturity and grows quite widely. It’s also cold hardy, very ornamental and almost without any thorns. The leaves are mostly simple. Sinton’s fruit is small (3cm), spherical or oval in shape. The rind is usually dark orange, thin, smooth and full of essential oils. The pulp has light orange color and is surprisingly dry, very acidic and the taste is similar to that of limes. Fruit’s flesh is divided into 6-8 segments with thin membranes and is almost seedless.
Segetrange -
hybrid bred in the 2nd filial generation of C.sinensis x Poncirus trifoliáta
This segetrange is a cross of orange tree and Poncirus in the 2nd filial generation. It is an erectly growing evergreen shrub with dark, narrow, very thin leaves similar to those of tangerines. Its petiole is extremely narrow, almost linear and the whole plant seems very ornamental and decorative. It blossoms very richly and the fruit of the Clementine size and navel orange shape. Sometimes the navel is the dominant element. The pulp is very tasty, similar to that of Clementine, very juicy. The influence of Poncirus cannot to be found in the fruit, which is almost completely seedless.
Sanford F2 Curafora is ideal for climates with winter temperatures of -12°C, it can even be planted in colder regions with adequate protection. Annual fertilizing supports the development of blossoms and fruits and many times the better the plant is fertilized, the more blossoms it will make. That’s why it is necessary to reduce the amount of fruit on the tree.
One Sanford F2 Curafora grown in Hamburg went through -24°C in 1995/96, but it was well mulched and several leaves and branches survived. The plant grew 40cm the next season.
This tree has a fruit very similar to grapefruit and so are other characteristics of this plant. Its hardiness could be compared to the hardiness of Satsuma. The fruit is a little bit more acidic than the grapefruit, but extremely juicy. And ripens in November.
USA 119 -
it is a cross of C.sinensis 'Succory' with a hybrid C.paradisi ‘Duncan’ x Poncirus trifoliata
USA 119 was bred in 1980 in selection of the USDA (United States Department of Agriculture) in Florida. The orange variety 'Succory' was crossed woth a hybrid of grapefruit 'Duncan' and Poncirus (citrumelo).
The tree is very robust and vigorous with very dense crown and round leaves (mono-, di- and trifoliate). The leaves have distinctively serrated extremely hardy leaves. The fruit usually crack after sudden and radical humidity changes (higher humidity is better).
USA 119 is the best hardy variety with the most quality fruit that ripens in November. They resemble medium sized oranges (6,5 7- cm) and weigh 160-170 g. Their rind is orange and about 3 mm thick. Its pulp is sweet and juicy, usually containing about 5-6 seeds.
It is possibleto grow it in the ground in our climate with adequate protection, it should withstand frosts as low as -12°C.
