47-560: The oroblanco , oro blanco , or sweetie ( Citrus grandis Osbeck × C. paradisi Macf. ) is a citrus hybrid , resulting from a cross between an acidless pomelo and a Marsh grapefruit . Its fruit is oblate and mostly seedless , with a thick rind that remains green long after it has already matured. It has a sweet, mild taste, and lacks the bitterness generally associated with grapefruit. It requires less heat to grow than other varieties of grapefruit and are harvestable sooner. Oroblancos grown in moderate climates tend to yield
94-559: A bitter taste due to their naringin content. The fruit's Brix / acid ratio, which contrasts a fruit's levels of sweetness and acidity, is considerably higher than those of other grapefruit varieties; in California, it is required to have a ratio of at least 10:1. By comparison, Marsh grapefruit tested in Australia were found to have a ratio of 4.5:1. Its aroma is "citrusy" and "floral". Prior to its release, researches planted oroblanco trees in
141-447: A decline of nearly 79 percent. Pomelo The pomelo ( / ˈ p ɒ m ɪ l oʊ , ˈ p ʌ m -/ POM -il-oh, PUM - ; Citrus maxima ), also known as a shaddock and from the family Rutaceae , is the largest citrus fruit . It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit . It is a natural, non-hybrid, citrus fruit, native to Southeast Asia . Similar in taste to
188-622: A different host. Aphids are the main vector by which CTV is transmitted. Initially the United States had as vectors only Aphis gossypii (melon-and-cotton aphid), A.spiraecola (green citrus aphid), and the black (or brown) citrus aphid Toxoptera aurantii . These aphids transmit the virus much less efficiently than Toxoptera citricida , the oriental citrus aphid. Toxoptera citricida had been found in East Asia and South America, and had slowly made its way up through Central America and
235-406: A diseased plant. The Mexican lime will develop highly predictable symptoms. Symptoms on the leaves begin as clear veins that turn corky, which is then followed by chlorosis and cupping of the leaf. Particularly severe strains may result in stunting, and stem-pitting may also occur. Alternatively CTV can be indicated by the presence of aggregates of cross-banded inclusion bodies in the phloem of
282-422: A leathery, dull green upper layer, and hairy under-leaf. The flowers — single or in clusters — are fragrant and yellow-white in color. The fruit is large, 15–25 cm (6–10 in) in diameter, usually weighing 1–2 kilograms (2–4 pounds). It has a thicker rind than a grapefruit, and is divided into 11 to 18 segments. The flesh tastes like mild grapefruit, with a little of its common bitterness (the grapefruit
329-414: A mild CTV strain at least four to six months prior to propagation. They should then be kept in a greenhouse , under aphid-free conditions. It is also recommended that nurseries of young plants grown for propagation should be kept vector-free. Top-grafting with pre-inoculated buds onto interstock trees infested with severe CTV is not effective, because the tree has little protection against the disease. It
376-721: A mild climate, a cold and humid climate, and a desert climate to analyze its production in different settings. They found that the specimens produced in the hotter climate were of a lower quality, and that those in the colder climate were excessively acidic. They thus determined that mild, inland climates were optimal for oroblanco growth. The oroblanco needs less heat than a standard grapefruit to sweeten and are harvestable sooner than other grapefruit varieties. Oroblancos have been cultivated in California , Florida , Israel , and Australia . In California, their harvest season can last from late November to March. In Australia, where they are grown in
423-600: A naturally occurring hybrid of the pomelo and the mandarin; however, genome analysis shows that it is actually a backcrossed hybrid between a pomelo and a sweet orange, which is why 63% of the grapefruit's genome comes from the pomelo. The bitter orange is a hybrid of wild type mandarin and pomelo; in turn, the lemon is a hybrid of bitter orange and citron , i.e. cultivated lemons have some pomelo ancestry. In addition, there has been repeated introgression of pomelo genes into both early cultivated hybrid mandarins and later mandarin varieties, these last also involving hybridization with
470-488: A relevant vector. The main cultural practice that increases the severity of the CTV is when the citrus trees are grafted onto the sour orange rootstock. Using CTV infected budwood for grafting can transfer the CTV from the original tree to the new one. When CTV was first discovered quarantine was the best management strategy, now quarantining only works for areas where a small amount of trees are infected. The other approach that
517-516: A resurgence in popularity after growers in Israel began growing the fruit. After branding the fruits "Sweeties" and "Golden Sweeties" and advertising their green peels and sweet flavor, Israeli growers found a large market of buyers for the oroblanco in Japan, where it became a success. Exports of the fruit from Israel and Australia to Southeast Asia also started around the same time. This led to an renewal of
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#1732851201519564-505: A sweet grapefruit, the pomelo is commonly eaten and used for festive occasions throughout Southeast and East Asia. As with the grapefruit, phytochemicals in the pomelo have the potential for drug interactions . The pomelo tree may be 5–15 meters (16–50 feet) tall, possibly with a crooked trunk 10–30 centimeters (4–12 inches) thick, and low-hanging, irregular branches. Their leaf petioles are distinctly winged, with alternate, ovate or elliptic shapes 5–20 cm (2–8 in) long, with
611-430: A thick, smooth peel which is very slow to transition from green to yellow; in fact, the rind only turns yellow weeks after the fruit has already matured. A consequence of its thicker rind is less edible flesh. It has a thick white pith and a large hollow core, and is oblate . Once mature, the fruit weigh roughly 400–500 grams (14–18 oz), and have a diameter of about 9 centimetres (3.5 in). A 2020 study found that
658-428: Is a hybrid of the pomelo and the orange). The enveloping membranes around the segments are chewy and bitter, considered inedible, and usually discarded. There are at least sixty varieties. The fruit generally contains a few, relatively large seeds, but some varieties have numerous seeds. The physical and chemical characteristics of pomelo vary widely across South Asia. The pomelo is significant botanically as one of
705-404: Is a non-hybrid variety; Banpeiyu may be another. Citrus tristeza virus Citrus quick decline virus Hassaku dwarf virus Lime dieback virus Citrus tristeza virus ( CTV ) is a viral species of the genus Closterovirus that causes the most economically damaging disease to its namesake plant genus, Citrus . The disease has led to the death of millions of Citrus trees all over
752-427: Is also known to infect Aeglopsis chevalieri , Afraegle paniculata and Pamburus missionis of the citrus subfamily Aurantioideae , as well as Passiflora gracilis which belongs to an entirely different lineage of rosid plants . CTV is distributed worldwide and can be found wherever citrus trees grow. Symptoms of CTV infection are highly variable and depend on several factors including host, virulence of
799-401: Is less efficient, it tends to have higher populations and thus can still transfer the virus fairly well. T. aurantii has been shown to only transmit certain strains of CTV. Of the three lesser efficient aphids, A. gossypii has a 78% transmission efficiency, while A. spiraecola and T. aurantii are between 0-6%. There is laboratory evidence that the psyllid Diaphorina citri may also be
846-410: Is limited to the phloem tissues of its host. It is transmitted semi-persistently by vectors that penetrate the phloem to extract sap, mostly the aphid species that colonize the crop. The brown citrus aphid is considerably more efficient at transmitting the virus than are other aphids that infest citrus. In Florida, it has been shown to be from six to twenty five times as efficient as Aphis gossypii ,
893-591: Is native it is commonly eaten as a dessert, sprinkled with salt or dipped in a salt mixture, or made into salads. In the Philippines, a pink beverage is made from pomelo and pineapple juice . The fruit may have been introduced to China around 100 BCE. In East Asia, especially in Cantonese cuisine , braised pomelo pith is used to make dishes that are high in fibre and low in fat. The pomelo, while not itself toxic, can cause adverse interactions similar to those caused by
940-489: Is necessary to spray nursery plants and young trees with insecticide occasionally, to control aphids. This should retard any re-infection with the virus. A biological approach has been to bring in a parasitoid wasp from Asia that naturally controls A. spiraecola . This approach was stopped when T. citricida arrived due to it not being a parasite of the more important aphid. There is a natural parasite of aphids in Florida in
987-424: Is recommended. The production of virus-free trees by shoot-tip grafting or heat treatment is very important. If it is possible to keep the field permanently free of CTV, the planting of virus-free trees is practical. In areas where it is difficult to find a virus-free field, preinoculation with a mild CTV strain protects trees against infection with a severe strain of CTV. Bud-stock trees should be inoculated with
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#17328512015191034-548: Is slow to transition from green to yellow, leading consumers to believe it was still unripe. Many of the trees planted were removed or had different grapefruit varieties grafted onto them. It was exported to Australian growers in 1990 and released there the same year, distributed by the Australian Nurserymen’s Fruit Improvement Company. It failed to gain popularity there as well, leading to many of those trees being removed. The oroblanco later saw
1081-567: Is susceptible to citrus tristeza virus ; a common symptom of CTV in oroblancos is stem-pitting, which stunts tree growth and leads to fruit of small size and low quality. It is also susceptible to fruit fly infestations. The oroblanco was first created as the result of a cross between an acidless pomelo ( C. grandis Osbeck ) and the Marsh grapefruit ( C. paradisi Macf. ) carried out in April 1958 by Robert Soost and James W. Cameron , geneticists at
1128-640: Is typically between 19.2 and 19.3 kb long and consists of a single strand of (+)-sense RNA enclosed by two types of capsid proteins. The size of its genome makes CTV one of the largest RNA viruses known. The CTV genome contains 12 open reading frames , which could encode at least 17 proteins . CTV infects several species of the plant genus, Citrus , including sour orange ( Citrus aurantium ) and any Citrus grafted onto sour orange rootstock , key lime and Seville orange ( C. × aurantifolia ), Hassaku and sweet orange ( C. × sinensis ), grapefruit ( C. × paradisi ), and mandarin ( C. reticulata ). CTV
1175-484: The Daily Value ), with no other micronutrients in significant content (table). The flesh and juice are edible, and the rind is used to make preserves , or may be candied. In Brazil, the outer part of the rind is used for making a sweet conserve , while the spongy pith of the rind is discarded. In Sri Lanka, it is often eaten as a dessert , sometimes sprinkled with sugar. In large parts of Southeast Asia where pomelo
1222-614: The University of California, Riverside . The cross resulted in seven cultivars , of which six were triploids and one was a tetraploid. In 1962, these seven cultivars were planted in fields in Riverside ; later, trees were also planted at research stations in Exeter , Santa Ana , and the Coachella Valley to test its production in differing climates. Of the cultivars planted, one labelled 6C26,20
1269-476: The temperate , subtropical , and tropical zones, harvest can last anywhere from February to December, depending on the region and how much heat is received. Its yield size may vary; during seasons of heavier yields, the average size of the fruit decreases. The tree of the oroblanco quickly grows tall and spreads outward, requiring an allowance of more than 20 feet horizontally when cultivated, and usually begins to yield fruit within five years of being planted. It
1316-482: The Caribbean Islands. By 1993 it had reached Cuba, and in 1995 it was found in Florida. The aphids require at least 30 to 60 minutes of feeding to acquire the virus, and remain viruliferous for at least 24 hours after. T. citricida is much more efficient than the other aphids, and it can transmit CTV strains causing severe stem pitting or decline that the other aphids cannot vector. Even though A. spiraecola
1363-405: The diseased plant. Other diagnostic procedures include electron microscopy , double-antibody sandwich enzyme-linked immunosorbent assay (DAS- ELISA ), tissue-print ELISA, and PCR -based assays. These methods identify signs of the virus, such as its microscopic structure (electron microscopy), the presence of its proteins’ antigens (ELISA) or the presence of its RNA (PCR). CTV is a virus that
1410-543: The first symptoms are noticed. In this case the infected tree will also show a bulge above the bud union and honeycombing on the inner face of the original sour orange root stock bark. The decline may also be quick, resulting in host death just days after the first symptoms are noticed. Stem-pitting is another symptom of CTV that manifests in most host types under the proper conditions, and especially in Citrus trees grafted onto sour orange rootstock. The host will develop pits in
1457-408: The fruit retained many of the compounds found in grapefruit including terpenes and polyphenols . The flavor of the oroblanco is mild and sweet. As it descends from an acidless pomelo, it lacks the bitterness generally associated with grapefruit, although it does attain an acidic aftertaste if grown in colder environments, or if eaten earlier in the growing season. Its rind and membrane also possess
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1504-598: The gall midge family Cecidomyiidae that attempts to keep aphid levels down, however due to the influx in aphid population it has not been able to keep populations down. CTV is the most economically important and damaging virus of citrus trees. It can be spread quickly and do damage not only by killing trees with sour orange rootstock, but also by stem pitting normal citrus trees. It has killed more than 80 million trees worldwide, mainly in South Africa since 1910, Argentina (10 million) and Brazil (6 million) since 1970, and
1551-455: The grapefruit with a wide range of prescription drugs . These occur by the inhibition of cytochrome P450 -mediated metabolism of prescription drugs including for example some anti-hypertensives , some anticoagulants , some anticancer agents , some anti-infective agents , some statins , and some immunosuppressants . The seeds of the pomelo are monoembryonic , producing seedlings with genes from both parents, but they are usually similar to
1598-556: The highest-quality fruit. The hybrid was first created by two geneticists at the University of California, Riverside , James W. Cameron and Robert Soost , in April 1958. It was later released to growers in 1980, who rapidly adopted it. It initially struggled in American markets, but had a resurgence in popularity after growers in Israel began advertising its sweet taste and green color to consumers in Japan , China , and Southeast Asia . It
1645-509: The island in the late 1640s). From there the name spread to Jamaica in 1696. The fruit is called jambola in varieties of English spoken in South Asia , and jabong in Hawai'i. Raw pomelo flesh is 89% water, 10% carbohydrates , 1% protein , and contains negligible fat . A 100-gram reference amount provides 159 kilojoules (38 kilocalories) of food energy , and is rich in vitamin C (68% of
1692-416: The most efficient vector found in the state before the introduction of the brown citrus aphid prior to 1995. This efficiency is enhanced by the narrow host range of the brown citrus aphid and its tendency to produce winged forms in order to colonize new growth. A. gossypii has a much wider host range, including hundreds of plant species in Florida, and the transmission of the virus is blocked when it feeds on
1739-446: The particular virus strain, and environmental conditions. The three most common groupings of symptoms are decline (quick and slow), stem-pitting, and seedling yellows. Decline is generally exhibited with sweet orange, mandarin, or grapefruit when they are grafted on infected sour orange rootstock. This decline includes chlorotic leaves and general dieback of the infected tree. Decline may be slow, lasting several months to years after
1786-631: The same meaning. An alternative possibility is that the Dutch name derives from Portuguese pomos limões 'citrus fruit'. The specific name maxima is the female form of the Latin for 'biggest'. One theory for the alternative English name 'shaddock' is that it was adopted after the plant's introduction into Barbados by a 'Captain Shaddock' of the East India Company (apparently Philip Chaddock, who visited
1833-522: The sweet orange. Pomelo genes are thus included in many types of cultivated Citrus . According to the Oxford English Dictionary , the etymology of the word 'pomelo' is uncertain. It may be derived from Dutch pompelmoes . The Dutch name in turn has uncertain etymology, but is possibly derived from Dutch pompel 'swollen' or pompoen 'pumpkin', combined with limoes 'lemon, citrus fruit', influenced by Portuguese limões with
1880-408: The three major wild ancestors of several cultivated hybrid Citrus species, including the bitter orange and the grapefruit ; and less directly also of the lemon , the sweet orange , and some types of mandarin . The sweet orange is a naturally occurring hybrid between the pomelo and the mandarin , with the pomelo the larger and firmer of the two. The grapefruit was originally presumed to be
1927-479: The tree they grow from and therefore pomelo are typically grown from seeds in Asia. Seeds can be stored for 80 days at a temperature of 5 °C (41 °F) with moderate relative humidity. Citrus maxima is usually grafted onto other citrus rootstocks outside Asia to produce trees that are identical to the parent; high-quality varieties are propagated by air-layering or by budding onto favored rootstocks. Dangyuja
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1974-561: The tree's cultivation in the United States , with trees being planted in California and Florida . Israel also found buyers for oroblancos in China ; 3,000 tons of the fruit were exported there by Israel in 2018. Regardless, oroblanco yield still trails behind that of the more popular Marsh grapefruit, and despite its resurgence, it continues to decrease in popularity in California, falling from 1,105 acres of oroblancos in 2004 to 233 acres in 2024,
2021-453: The trunk and stem. This results is decreased tree vigor and reduced fruit yield. This is typically caused by the more virulent strains of CTV. The third major symptom of CTV infection is seedling yellows. This tends to occur on sour orange, Natsudaidai , lemon and buntan . Symptoms include yellowing of foliage and general dieback. CTV is classically diagnosed by graft-inoculating a Mexican lime ( Citrus aurantifolia ) with tissue from
2068-550: The world and has rendered millions of others useless for production. Farmers in Brazil and other South American countries gave it the name "tristeza", meaning sadness in Portuguese and Spanish, referring to the devastation produced by the disease in the 1930s. The virus is transmitted most efficiently by the brown citrus aphid . CTV is a flexuous rod virus with dimensions of 2000 nm long and 12 nm in diameter. The CTV genome
2115-665: Was adopted after T. citricida came to the U.S. was destroying any tree in which the budwood was not free of CTV. This is a more drastic measure but must be done due to how fast T. citricida can spread the virus. If there is any CTV in the area, avoid grafting trees on sour orange rootstock and instead graft on tristeza-tolerant rootstock. Since the virus has been in Asia a long time they have used rootstock from trifoliate orange , Sunki , and Shiikuwasha ( C. × depressa ) for many years. Some hybrids, such as Troyer citrange or Swingle citromelo , show promise as resistant root-stock. Also, using scion varieties tolerant to stem pitting
2162-537: Was exported to growers in Australia in 1990, where it was also commercially unsuccessful. The oroblanco is a triploid citrus hybrid , resulting from a cross between an acidless pomelo ( C. grandis Osbeck ) and the Marsh grapefruit ( C. paradisi Macf. ). Its fruit is seedless with pale yellow flesh and is slightly less juicy than other grapefruits, though it does have a juice content of roughly thirty percent. Rarely, it contains small, aborted seeds. It has
2209-627: Was selected and designated "oroblanco", meaning "white gold" in Spanish . The oroblanco was commercially released to growers in 1980, with the patent belonging to the Regents of the University of California . A separate cultivar from Soost and Cameron's cross in 1958 was also released under the name " melogold " in 1986. Following its release, the oroblanco was rapidly adopted by growers. However, it proved unpopular in American markets due to its thick peel, which
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