The United States Department of Agriculture (USDA) this Thursday in Washington announced that they have grants worth $22 million available for research against citrus greening disease. The Huanglongbing (HLB), commonly known as the citrus greening disease, is a serious affliction of citrus trees with no cure. The funding will be overseen by the USDA’s National Institute of Food and Agriculture (NIFA) division. The funds will be available through the Specialty Crop Research Initiative (SCRI) and the Citrus Disease Research and Extension Program (CDRE). The pre-applications for the funding will be available on the NIFA website until 16th May, and the invited applicants will then be allowed to submit a full application detailing their research and its relevance to the citrus industry by 18th August. Citrus are one of the most consumed fruits by the youth in the United States.

The USDA has already invested more than $380 million in short-term and long-term strategies against citrus greening from 2009 till 2015. The disease was first noticed in Florida in 2005. Since then it has spread to 15 US states and almost all citrus-producing areas have been under full or partial quarantine. As a result the Huanglongbing Multi-Agency Coordination (MAC) group was also formulated in December 2013, to assure statewide cooperation and to come up with tools and strategies for citrus growers for the interim. The group has already invested $20 million in over 30 projects in the past two years. Currently, citrus producers are economically productive in the US due to the use of techniques such as thermotherapy, soil acidification, bio-control etc.

The production of citrus fruits in the US has fallen dramatically from 8 million metric tons in 2011, due to citrus greening, to half of the amount. In only one year the production dropped by 1.0 million metric tons to reach a total production of only 4.8 million metric tons in 2015. Florida accounts for 60% of the overall citrus production in the US and is the most affected area by citrus greening. California, on the other hand, produced the other 40% of the US citrus demand. As a result of the disease, import of citrus fruits from countries such as China and Egypt has been on the rise.

“Since 2009, USDA has committed significant resources to manage, research and eradicate the citrus greening disease that threatens citrus production in the United States and other nations,” said Agriculture Secretary Tom Vilsack. “Thanks to the continued, coordinated efforts between growers, researchers, and state and federal governments, we are getting closer every day to ending this threat. The funding announced today will help us continue to preserve thousands of jobs for citrus producers and workers, along with significant revenue from citrus sales.”

Citrus Greening

The citrus greening, or the Huanglongbing (HLB) disease, is also called the yellow dragon disease. Citrus greening is caused by a bacterium (candidatus liberibacter asiaticus) present in the insect called the Asian Citrus Psyllid (Diaphorina citri Kuwayama) which feeds on the leaves and stems of citrus plants and thus transmits the bacterium. The disease is believed to have first originated from China in the 1990s and there is no known cure for the disease. Once infected the tree dies out within 5 to 12 years. Infected trees have small, yellowed leaves with yellowed shoots and stunted flowering, and their unmarketable fruit is misshapen with green and yellow hues along with a bitter taste. Almost all types of citrus species are susceptible to the disease e.g., orange, sweet orange, sour orange, mandarin orange, trifoliate orange, jasmine, lime-berry, grapefruit, lemon etc.

Citrus Fruits And Vitamin C

The citrus greening disease a poses a big problem for the US diet since citrus fruits and juices account for almost half of the total fruit consumption and are essentially compulsory for health, so their absence can leave a negative impact on the well-being of the general population. Citrus fruits are a major source of vitamin C which is also known as L-ascorbic acid. The water-soluble vitamin is an essential dietary component and important for a number of processes in the human metabolism.

“Citrus is well-known for its nutrition and health-promotion values. This reputation is derived from the studies on the biological functions of phytochemicals in citrus fruits and their derived products in the past decades,” as stated by Zhiqin Zhou, a horticulture and food science expert at the Southwest University in China. “In recent years, the antioxidant activity of citrus fruits and their roles in the prevention and treatment of various human chronic and degenerative diseases have attracted more and more attention. Citrus fruits are suggested to be a good source of dietary antioxidants.”

Vitamin C is basically required by the human body for:

  • Biosynthesis of collagen (L-carnitine) to form and maintain connective tissues, cartilage, bones, teeth, wound healing etc
  • Protein Metabolism i.e., formation of skin, tendons, ligaments, and blood vessels etc
  • ATP formation (the citric acid cycle)
  • Antioxidant i.e., limits the damaging effects of free radicals in the body
  • Precursor of numerous hormones e.g., alpha-tocopherol (vitamin E)
  • Improve absorption of iron from plant sources

The recommended daily amount of vitamin C consumption for a male adult is 90 mg, while for a female it is 75 mg, with a 10 mg increase recommended during pregnancy. As mentioned before citrus fruits are an excellent source of vitamin C. For example, in a single serving of orange juice equal to ¾ cup, about 93 mg of vitamin C is present and a medium sized orange contains 70 mg of vitamin C.

Since vitamin C is such a vital part of our diet, its deficiency can lead to:

  • Anemia
  • Bleeding gums
  • Lowered immunity
  • Slow wound healing
  • Dry and rough hair and skin
  • Bruising
  • Gingivitis i.e., inflammation of the gums
  • Weakening of tooth enamel
  • Weight gain
  • Pain and swelling in joints

Acute vitamin C deficiency can lead to a critical disease called scurvy.

Studies have found that regular vitamin C consumption also decreases the risk of:

  • Cancer
  • Heart diseases
  • Cataracts
  • Age-related macular degeneration (AMD)
  • Common cold
  • Osteoarthritis
  • Asthma
  • Pre-Eclampsia