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Citrus Resource


About Citrus


History of citrus

“Citrus” is both a common name and a genus within the family Rutaceae. The common name “citrus” may refer to fruits within the genus proper (i.e. oranges, lemons, grapefruits, and limes), but is also often used to refer to closely related fruits in other genera, such as kumquats (Fortunella). There are perhaps only three true species of Citrus: Citrus maxima (pummelo), C. medica (citron), and C. reticulata (mandarin). All other citrus known today are hybrids of these three species, even those that grow true from seed. Oranges are hybrids of pummelo and mandarin, grapefruits are hybrids of pummelo and orange, lemons and limes are hybrids of citron and an unknown species. Even kumquats are hybrids of mandarin.

Citrus is believed to have originated in the part of Asia bordered by India, Myanmar (Burma), and China. Citrus fruit has been cultivated in India and China since ancient times, and is now cultivated in warm climates throughout the world. Citron seeds have been found in Mesopotamian excavations, but it was first cultivated in Persia. Alexander the Great brought citron to Greece when he conquered the Persian Empire in 327 BC, and Greek colonists brought them to Palestine around 200 BC. Known as etrog in the Jewish tradition, the fruit has a prominent role in the autumn Feast of the Tabernacles, or Sukkot, and so the fruit followed the Jewish people as they colonized the Mediterranean. Other citrus fruits followed a similar path from Asia to southern Europe, largely brought by Arabs, who colonized the areas in the Mediterranean that were left free by the Romans. By the end of the Middle Ages, citron, sour orange, lemon, and lime were widely cultivated in Italy, Spain, and Portugal. The sweet orange did not arrive from China until the mid 1500s, but was widely cultivated in both Italy and Spain by the beginning of the seventeenth century.

Citrus cultivation in the U.S.

Citrus was brought to America by the Spanish and Portuguese, starting in the West Indies, then to Mexico, Brazil, and Florida. Catholic missionaries brought citrus plants with them to California from northern Mexico. Citrus cultivation gradually spread in both California and Florida, eventually becoming some of the dominant industries in each state. The New World (primarily Florida, California, and Brazil) is now responsible for the bulk of citrus production worldwide.

The first Florida citrus trees were planted near St. Augustine by Spanish explorers, most likely Ponce de Leon. The sandy soil and subtropical climate proved to be ideal for growing citrus, and the Florida citrus industry grew quickly in the 19th century, with production up to 5 million boxes of fruit each year by the 1890s. Demand for citrus fruit in the northeast along with rail lines that allowed shipping long distances enabled this growth. The Florida industry was devastated during the Great Freeze of the winter of 1894-1895, and production dropped to 147,000 boxes. But growers picked up and moved south, and production rebounded to pre-freeze levels within 15 years. Today, Florida is the world’s biggest producer of grapefruit, shipping it all over the world. Florida lead the U.S. in production of oranges for processing, and produces the majority of the orange juice that is consumed in the U.S.

Though citrus was first brought to the state much earlier, California citrus production was largely propelled through the introduction of the navel orange in the 1870s. Brought to Brazil from Portugal in the early 1800s, the navel orange was a mutation of the original variety that was seedless, sweet, juicy, and easy to peel. The USDA obtained cuttings of this tree and sent a few starter trees to Eliza Tibbets in Riverside to see how they would fare in the California climate. Though they required irrigation, these trees were the key to the start of the California citrus industry. One of these trees still stands and bears fruit in downtown Riverside. The industry really took off in the 1940s, following advances in large-scale irrigation technology. California is first in the U.S. in the fresh orange market, and produces a large share of the nation’s valencias, lemons, grapefruits, and tangerines.

Arizona and Texas also contribute to the U.S. citrus industry. According to historical records, citrus appears to have reached Arizona before California, but it never expanded beyond a few plantings scattered around in home gardens until the beginning of the twentieth century. The establishment of citrus cooperatives eliminated many costly transportation problems, enabling the industry to grow. Today, Arizona is second in the nation in production of lemons, third in tangerines, and also produces oranges and grapefruit. The Texas citrus industry today is comprised almost entirely of grapefruit production, and was largely made famous through the creation of several sweeter varieties of red grapefruit in the 1970s and 1980s. Texas citrus has been impacted many times by serious freezes, and so citrus cultivation is now restricted to the southern-most areas of the state.

Pests and diseases of citrus

Citrus pests and diseases pose a great threat to the citrus industry in the U.S. Citrus can be damaged by a wide variety of insect, mite, and nematode pests, but not all cause significant damage. Whiteflies and soft scales both can cause leaf curling and yellowing through their sap feeding and honeydew production. The sticky honeydew can also attract ants and promote the growth of sooty mold. Armored scales are also sap feeders, and cause similar leaf damage, but they do not produce honeydew. Fruit flies can cause damage to the fruits; the females puncture the fruit to lay their eggs, and the larvae feed on the fruit when they hatch. Moth larvae feed on leaves and are capable of defoliating an entire tree in a few days. Beetle larvae attack the roots, stems, and trunks of the trees, while the adults often feed on the leaves. Mites can attack the fruits, leaves, or buds, but are also vectors for viruses such as citrus leprosis virus. In fact, many of the most important citrus pests are vectors for disease. Aphids, psyllids, and other sap-sucking insects are often problematic more due to their ability to vector diseases than the direct damage they can cause.

There are four diseases that are currently of greatest concern to U.S. citrus. Citrus greening, also known as huanglongbing or yellow dragon disease, is one of the most serious citrus plant diseases in the world. Citrus greening is caused by a phloem-limited bacterium that is transmitted by Asian citrus psyllid (pictured above). There is not a cure for citrus greening, and it kills most infected trees within a few years. Citrus canker has struck U.S. citrus many times over the years, but it appears to now be established in Florida. Also a bacterial disease, citrus canker causes the tree to decline in health, prematurely dropping leaves and fruit, until the tree ceases fruit production altogether. It affects all types of citrus and is very easily spread. Citrus black spot is one of the most serious fungal diseases of citrus in the world. Common in subtropical regions of the world with summer rainfall, citrus black spot was detected in Florida in 2010. It leaves the fruit highly blemished and unsuitable for sale. The fourth disease, sweet orange scab, was also confirmed in the United States in 2010, this time in Texas. Sweet orange scab is a fungal disease, and it primarily causes cosmetic damage to fruit, making it unsuitable for sale in the fresh market.


Citrus Resource
June 2012