High School High School Society and the World

Citrus Greening Part One: Fruit Crisis

Enjoy that glass of orange juice for breakfast while you can.

Image from Pexels

Over past decades as genetic engineering developed, the technology soon merged into the field of agriculture: affecting countries worldwide, especially in the US. Genetically modified crops are more tolerant against harsh environments, insects, and other toxins.

In Florida, a disease is spreading, not to humans, but to plants. This disease, Huanglongbing, as known as Citrus Greening, is caused by bacteria and psyllids such as Asian Citrus Psyllid that damages the plant’s tissues. Plants, especially orange trees, are widely affected. A psyllid feeds on healthy trees and injects the bacterium into the phloem, the vascular tissue that conducts and transports sugar and nutrients, of orange trees. (1)

mature Psyllids on trees
Mature psyllids feeding and laying eggs on trees (Image from ANR)

There is no cure for the disease: the bacteria is inside the vascular system of the plant, making it extremely difficult for scientists to access. The orange trees that are affected go from producing sweet, juicy, and delicious oranges to making sour, bitter, and misshapen ones. (2)

Color Transformation
Before and After Citrus Greening (Image from National Academics Press)

In Florida, this disease has devastated farmers, forcing them to leave one hundred thousand acres of orchards behind. From 240 million boxes of oranges in 2004, Florida’s orange production has plummeted to 70 million boxes last year in 2017, which is the lowest in decades (3). Additionally, other fruits such as grapefruit, lemons, and limes are affected (2).

This outbreak is devastating and in order to save Floridian citruses, this problem has to be solved. According to Nature.com, this disease has decreased U.S. orange production by half over past decades and based on a research article, Florida citrus industry is estimated to have a $9.3 billion economic impact for the state (4 & 5). As this crisis forces farmers in Florida to quit growing citruses, the price of oranges and relevant products, including orange juice, is increasing over time. Gradually, citrus greening has spread throughout Florida beginning in 2005. Clearly shown in the picture, nearly every single tree in South Florida has been infected by the citrus psyllids. Moreover, citrus greening has already affected commercial fruit industries in Thailand, Vietnam, Saudi Arabia, parts of Africa, and South America (5).

022009 grow
Spreading of Citrus Greening in Florida (Image from Huffington Post)
Citrus Greening World Wide (Image from National Academics Press)

Since this disease has affected about 80% of the trees in Florida and is spreading in the world, researchers in the state and across the world are trying to find effective ways to save this crisis. First, to stop the spreading of this disease, the USDA (United States Department of Agriculture) has enforced laws and regulations to prevent people from moving fruit trees and their branches to other locations without permission. (2)

Some farmers are trying out groves with mesh netting that shields the trees from infection. Arnold Schumann, a faculty member who works in the facility in Lake Wales, Florida, states that screened enclosure is an easy and effective way to protect citrus trees from greening. However, the problem is, this could be unaffordable for orange farmers who lost money due to greening (6). According to National Academics of Sciences Engineering Medicine, the huge industry Citrus Research and Development Foundation (CRDF) has invested almost 90 percent of its funds to research this disease (5). In 2017, South Garden Citruses, one of the world’s largest orange juice manufacturers, was approved by the USDA to begin genetically testing citrus trees (2). By genetic engineering the plants, farmers no longer have to use expensive and harmful pesticides, and this opens a gateway for long-term solutions.

Screened Enclosure (Image from National Public Radio)

This article is revised from my research project over the past year. Part two will be out soon.


(1) “Citrus Greening.” USDA APHIS | Research Facility Annual Summary Report, http://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/citrus-greening/citrus-greening-hp?utm_campaign=crosby-2017&utm_source=hungrypests-com&utm_medium=redirect&utm_keyword=/the-threat/citrus-greening.php.

(2) Voosen, Paul. “Can Genetic Engineering Save the Florida Orange?” National Geographic, National Geographic Society, 14 Sept. 2014, news.nationalgeographic.com/news/2014/09/140914-florida-orange-citrus-greening-gmo-environment-science/.

(3) CBS. “Florida Farmers In Crisis Over Citrus Greening Disease.” CBS Miami, CBS Miami, 26 Oct. 2016, miami.cbslocal.com/2016/10/26/florida-farmers-in-crisis-over-citrus-greening-disease/.

(4) Ledford, Heidi. “Geneticists Enlist Engineered Virus and CRISPR to Battle Citrus Disease.” Nature News, Nature Publishing Group, 16 May 2017, http://www.nature.com/news/geneticists-enlist-engineered-virus-and-crispr-to-battle-citrus-disease-1.21997.

(5) “Read ‘Strategic Planning for the Florida Citrus Industry: Addressing Citrus Greening Disease’ at NAP.edu.” National Academies Press: OpenBook, 2010, http://www.nap.edu/read/12880/chapter/4#18.

(6) Allen, Greg. “After A Sour Decade, Florida Citrus May Be Near A Comeback.” NPR, NPR, 4 Dec. 2016, http://www.npr.org/sections/thesalt/2016/12/04/503183540/after-a-sour-decade-florida-citrus-may-be-near-a-comeback.

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