Citrus production

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Major citrus growing regions.
Gathering oranges in Cayo, Belize.

Citrus fruits are the highest value fruit crop in terms of international trade. There are two main markets for citrus fruit:

  • the fresh fruit market
  • the processed citrus fruits market (mainly orange juice)

Most citrus production is accounted for by oranges, but significant quantities of grapefruits, pomeloes, lemons and limes are also grown.

History[edit]

While the origin of citrus fruits cannot be precisely identified, researchers believe they began to appear in southeast Asia at least 4000BC. From there, they slowly spread to northern Africa, mainly through migration and trade. During the period of the Roman Empire demand by higher-ranking members of society, along with increased trade, allowed the fruits to spread to southern Europe. Citrus fruits spread throughout Europe during the Middle Ages, and were then brought to the Americas by Spanish explorers. Worldwide trade in citrus fruits didn't appear until the 19th century and trade in orange juice developed as late as 1940.[1]

Volume[edit]

Total production and consumption of citrus fruit has grown strongly since the 1980s. Current annual worldwide citrus production is estimated at over 70 million tons, with more than half of this being oranges. According to the United Nations Conference on Trade and Development (UNCTAD), the rise in citrus production is mainly due to the increase in cultivation areas, improvements in transportation and packaging, rising incomes and consumer preference for healthy foods.

This trend is projected to change from 2000 to 2010 since the high production levels have slowed the rate of new plantings.[1]

Countries involved[edit]

Citrus fruits are produced all over the world. According to UNCTAD, in 2004 there were 140 citrus producing countries. Around 70% of the world's total citrus production is grown in the Northern Hemisphere, in particular countries around the Mediterranean and the United States, although Brazil is also one of the largest citrus producers.

In the United States, citrus fruits for consumption as fresh fruit are mainly grown in California, Arizona and Texas, while most orange juice and grapefruit is produced in Florida.[2]

China could be a major player in the orange juice and processed citrus markets, except for high tariffs on citrus that make domestic sale more profitable. Though citrus originated in southeast Asia, current citrus production is low due to lower than average yields, high production and marketing costs and problems with disease.[3]

Citrus production in most of Europe continues to decline, although the clementines produced by Spain are increasing in popularity among consumers.[4]

Top ten total citrus fruits producers 2007 (tonnes)
World's top producer in each category is given in grey
Country Grapefruit Lemons and limes Oranges Tangerines, etc.[5] Other Total
 Brazil 72,000 1,060,000 18,279,309 1,271,000 - 20,682,309
 China 547,000 745,100 2,865,000 14,152,000 1,308,000 19,617,100
 United States 1,580,000 722,000 7,357,000 328,000 30,000 10,017,000
 Mexico 390,000 1,880,000 4,160,000 355,000 66,000 6,851,000
 India 178,000 2,060,000 3,900,000 - 148,000 6,286,000
 Spain 35,000 880,000 2,691,400 2,080,700 16,500 5,703,600
 Iran 54,000 615,000 2,300,000 702,000 68,000 3,739,000
 Italy 7,000 546,584 2,293,466 702,732 30,000 3,579,782
 Nigeria - - - - 3,325,000 3,325,000
 Turkey 181,923 706,652 1,472,454 738,786 2,599 3,102,414
 World 5,061,023 13,032,388 63,906,064 26,513,986 7,137,084 115,650,545
Source: Food And Agricultural Organization of United Nations: Economic And Social Department: The Statistical Division


Oranges and orange juice[edit]

About a third of citrus fruit production goes for processing: more than 80% of this is for orange juice production. Demand for fresh and processed oranges continues to rise in excess of production, especially in developed countries([6]).

The two main players are Florida in the United States and São Paulo in Brazil. Production of orange juice between these two makes up roughly 85 percent of the world market. Brazil exports 99 percent of its production, while 90 percent of Florida’s production is consumed in the US.[2]

Orange juice is traded internationally in the form of frozen concentrated orange juice to reduce the volume used, so that storage and transportation costs are lower.[4]

Citrus canker[edit]

Main article: Citrus canker

Citrus production is often cut short in many areas by outbreaks of bacteria known as Xanthomonas axonopodis, or Citrus canker, which cause unsightly lesions on all parts of the plant, affecting tree vitality and early drop of fruit. While not harmful to human consumption, the fruit becomes too unsightly to be sold, and entire orchards are often destroyed to protect the outbreak from spreading.[7]

Citrus canker affects all varieties of citrus trees, and recent outbreaks in Australia, Brazil and the United States have slowed citrus production in parts of those countries. Citrus leafminer moths are a major concern where citrus canker exists. The openings created by citrus leafminer make the tree highly susceptible to the X. axonopodis bacteria which leads to citrus canker. Dcept CLM is an effective mating disruptant of citrus leafminer moths, impeding males to mate.[8] Dcept CLM is composed entirely of and non-toxic inert and active ingredients: it uses the sex pheromone of citrus leafminers to disrupt their mating behavior. Dcept CLM is designed to be applied manually, and a single application promotes effective population control for more than 30 weeks in the field. For the US, this product is approved for mating disruption control by the US Environmental Protection Agency.

Citrus Greening Disease in Florida[edit]

Introductory and effects of disease[edit]

Huanglongbing (HLB), called citrus greening within the industry, is recognized as the deadliest citrus disease the Florida citrus industry has ever faced.[9] This can be attributed to the economic costs of implementing new care-taking strategies, and overall tree loss creating a loss of revenues.[10] A look at total Florida citrus growing acreage provides a tangible impression to the hardships citrus greening provides; in 2000 there was 665,529 commercially producing citrus acres, while in 2011 there were 473,086 commercially producing citrus acres in Florida.[11] Every year citrus reports indicate a continued loss of citrus production. Citrus greening is being attributed for a total output impact of -4.51 billion, and a loss of 8,257 jobs within the state of Florida.[10] The disease has now spread throughout the entire state, and affects every Florida citrus grower.[12] The disease is spread through an insect vector, the Asian citrus psyllid. The psyllid was previously introduced into Florida in 1998. At this time citrus greening was never found within the state, thus the psyllids spread was left unchecked. By the time citrus greening had reached Florida psyllid populations were well established throughout the state of Florida. The first positive case of greening disease was in August 2005, when a greening positive citrus tree was discovered in Miami-Dade County. It was at this time the entire Florida citrus industry changed its citriculture practices overnight. Intensive pesticide applications, aggressive removal of citrus greening positive trees, and the complete switch from outdoor to indoor citrus nursery operations transpired.[11]

Symptoms[edit]

Negative citrus greening tree vs Positive citrus greening tree

Symptoms of citrus greening are numerous, and can be varied in citrus trees. A tree will develop yellow shoots instead of the expected deep green colors. The disease presents itself on the leaves by giving an asymmetrical blotchy-mottle appearance. This is the key diagnosing characteristic of citrus greening. On affected limbs, fruit tend to be lopsided. The fruit will also never ripen and have a sour taste, making them unmarketable for both juice and fresh fruit productions. In later stages of infection the tree will suffer from heavy leaf drop, high percentages of fruit drop, and deep twig die back. A greening positive citrus tree’s canopies will be airy due to the defoliation the disease causes.[12] After a tree becomes infected with citrus greening it becomes uneconomical and may die within 2–5 years.[13]

Ecology of spread[edit]

Vector control of citrus greening began when the disease was first introduced in 2005. All commercial citrus growers are advised in applying two dormancy pesticide sprays. These broad-spectrum pesticide sprays are applied in winter when adult psyllid populations decline to almost exclusive overwintering adults. With this strategy, significant reductions of populations withhold for up to 6 months. This fact is crucial as it protects the spring flush, which accounts for over 70% of new leaves for the year, from the infectious psyllid attacks. The spring flush typically occurs 3 months past winter.[14] More aggressive citrus grove care-takers may employ a wide host of pesticides to try and keep psyllid populations low year round. These growers may spray pesticides up to 7 times a year rotating various pesticides to employ different modes of actions against the psyllid.[15] This is done in an attempt to prevent resistances of psyllids to the various pesticides. The spraying of pesticides is the only method of control for the citrus greening vector, the psyllid. It is impossible to kill all psyllids through pesticides, thus strategic timing of pesticide sprays are done to try and slow the gradual spread of HLB throughout the citrus grove. Unfortunately, at this time it is inevitable that a commercial citrus grove will reach 100 percent infection rates even with aggressive sprays.[16]

New care-taking strategies[edit]

Productivity of a citrus groves can be retained at pre-Huanglongbing levels through a three pronged strategy. Current research is aimed at the goal of giving the greatest yields for the lowest costs. Indeed, these lower costs are necessitated by the increased per acre cost of caretaking brought upon by Huanglongbing infection. Huanglongbing forces the commercial citrus caretaker to spray his/her block of citrus many more times a year than normal, considerably increasing costs. Per pound prices of citrus must continue increasing for citrus to remain profitable due to disease pressure.[17]

Foliar fertilizers are now being sprayed on citrus trees at considerably higher rates than before citrus greening disease. Inspiration for the mixture of foliar nutrients was drawn from a local citrus grower, Maury Boyd. Mr. Boyd was the first to try a strategy of not removing greening positive citrus trees, and instead attempt aggressive nutritional sprays. His grove was as a result the first to remain economical with a high percentage rate of greening disease infection. His spray program is under considerable research by the University of Florida’s IFAS department. Further research is still needed, and being carried out to determine which specific fertilizer compounds, and the quantities used are the most efficient.[18]

Vector control of the psyllid, which is the sole means for citrus greening to spread is now done routinely. Before citrus greening disease was introduced, commercial citrus growers did not have to spray pesticides targeting insects. Current research is aimed at pesticide application timing, and pesticide choice for efficacy.[19]

After the introduction of citrus greening disease, all commercial nurseries, where new young trees are purchased, were relocated indoors and a bud wood registration program was enacted. Previously young citrus trees were grown outdoors before disease pressure became an issue. This is to certify that Florida grove owners are able to purchase clean citrus trees for the planting of citrus groves. A greening positive young citrus tree will never reach maturity, even with intensive sprays.[11]

These three keystone citriculture practices vector control, foliar nutrition, and certified young trees make up the new best management practices for commercial citrus growers against the citrus greening disease fight.[11]

References[edit]

  1. ^ a b H. John Webber (1967). History and Development of the Citrus Industry. University of California Division of Agricultural Sciences. 
  2. ^ a b USDA Foreign Agricultural Service. "USDA - U.S and the World Situation: Citrus" (pdf). 
  3. ^ Cheju Citrus Research Institute, Korea. "Citrus Production in Asia". Asian Studies on the Pacific Coast. Archived from the original on 2006-10-07. 
  4. ^ a b Thomas H. Spreen. Projections of World Production and Consumption of Citrus to 2010. 
  5. ^ Includes tangerines, mandarins, and clementines.
  6. ^ Vange Salem
  7. ^ Gottwald, T.R, Graham, J.H. and Schubert, J.S. (2002). Citrus canker: The pathogen and its impact. Online. Plant Health Progress doi:10.1094/PHP-2002-0812-01-RV
  8. ^ Anonymous 2013. Online. Dcept CLM: For the mating disruption control of citrus leafminer, Phyllocnistis citrella
  9. ^ Shen, W; Crevallos-Crevallos, J; Nunes da Rocha, U; Arevalo, H; Stansly, P; Roberts, P; H.C. van Bruggen, A (2013). "Relation Between Plant Nutrition, Hormones, Insecticide, Applications, Bacterial Endophytes, and Candidatus Liberibacter ct Values in Citrus Trees Infected with Huanglongbing". Eur J Plant Pathol (137): 727–742. 
  10. ^ a b Hodges, A; Spreen, T (2012). "Economic Impacts of Citrus Greening (HLB) in Florida, 2006/07-2010/11". IFAS: 1–6. 
  11. ^ a b c d Hall, D; Richardson, M; El-Desouky, A; Halbert, S (2012). "Asian Citrus Psyllid, Diaphorina Citri, Vector of Citrus Huanglongbing Disease". Entomol. Exp. Appl. (146): 207–223. 
  12. ^ a b Gottwald, T; Graca, J; Bassanezi, R (2007). "Citrus huanglongbing: The Pathogen and Its Impact". Plant Health Progress (10): 1094. 
  13. ^ Croxton, S; Stansly, P (2013). "Metalized Polyethylene Mulch to Repel Asian Citrus Psyllid, Slow Spread of Huanglongbing and Improve Growth of New Citrus Plantings". Pest Manag Sci (70): 318–323. 
  14. ^ Stansly, P; Arevalo, H; Qureshi, J; Jones, M; Hendricks, K; Roberts, P; Roka, F (2013). "Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing". Pest Manag Sci (70): 415–426. 
  15. ^ Tiwari, S; Mann, R; Rogers, M; Stelinski, L (2011). "Insecticide Resistance in Field Populations of Asian Citrus Psyllid in Florida". Pest Manag Sci (67): 1258–1268. 
  16. ^ Croxton, S; Stansly, P (2013). "Metalized Polyethylene Mulch to Repel Asian Citrus Psyllid, Slow Spread of Huanglongbing and Improve Growth of New Citrus Plantings". Pest Manag Sci (70): 318–323. 
  17. ^ Stansly, P; Arevalo, H; Qureshi, J; Jones, M; Hendricks, K; Roberts, P; Roka, F (2013). "Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing". Pest Manag Sci (70): 415–426. 
  18. ^ Stansly, P; Arevalo, H; Qureshi, J; Jones, M; Hendricks, K; Roberts, P; Roka, F (2013). "Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing". Pest Manag Sci (70): 415–426. 
  19. ^ Stansly, P; Arevalo, H; Qureshi, J; Jones, M; Hendricks, K; Roberts, P; Roka, F (2013). "Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing". Pest Manag Sci (70): 415–426. 

External links[edit]