May 12th, 2013 by Michael Ricciardi
The State of Florida’s $9 billion annual orange crop is under serious threat from ‘citrus greening’ disease (also known by its Asian name huanglongbing); some citrus farmers are calling it the worst threat to their crop in over half a century.
The disease is caused by a bacterium called Candidatus Liberibacter asiaticus, which, as the name indicates, was brought here via imported plants from various points in Asia. Most all plant-infecting bacterial diseases need an agent, or ‘vector’, to spread them; in this case, the vector is a tiny, sap-sucking insect called the Asian citrus psyllid (Diaphorina citri), which travels from tree to tree, infecting them as it goes.
There are other diseases that infect citrus fruit, such as canker disease, but this disease ends up killing the entire tree. Trees infected with the bacterium often take several years before they show symptoms: leaves turn yellow and then fall off, then the fruit fails to ripen and falls to the ground prematurely, and, eventually, the tree itself dies.
In an interview with the NY Times, long-time citrus grower Vic Story observed:
“We have got a real big problem. It’s definitely the biggest threat in my lifetime, and I’m 68. This is a tree killer.” [quote source]
There is no know cure for the disease which also infects other citrus fruit crops like grapefruit and lemons. The bacterium’s impact on citrus crops is so severe that in 2003 it was classified as a ‘bio-terror’ weapon, according to a report in The New Yorker.
To date, the disease has spread to all 32 of Florida’s citrus growing counties. But greening disease has also been reported in several other States including Texas, California and Arizona. Beyond the US, China, Mexico and Brazil (the world’s dominant producer of oranges) are also experiencing infestations.
According to a report from the University of California, Davis, Division of Agriculture and Natural Resources, between 1985 and 2003, there were 170 cases of the Asian citrus psyllids intercepted at US ports. As one can surmise, there were plenty of other infected plants that slipped through. No numbers for total intercepted (infected) plants are available from the last 9 years.
In the same NY Times article, US Senator Bill Nelson commented:
“The industry that made Florida, that is synonymous with Florida, that is a staple on every American breakfast table, is totally threatened. If we don’t find a cure, it will eliminate the citrus industry.”
In April, The USDA estimated an 11% decline from October 2012 in its forecast of Florida’s orange crop output for this year. Adding to this troubling projection, Florida’s rainfall in 2013 has been 40 to 70% lower than the past 30 year’s average.
One should probably expect the price of orange juice to increase by year’s end.
Efforts to Combat the Disease
Florida citrus growers have currently contributed some $60 million to establish a research center to combat the disease.
Additionally, the Florida legislature recently approved an $8 million research fund, and, all the way across the country, Washington State University has initiated a $9 million project to develop genetically altered psyllids that are resistant to infection from the citrus greening-causing bacterium.
Also: Coca-Cola, which owns Minute Maid, has announced its intent to invest $2 billion to plant 25,000 acres of new orange groves in the Sunshine State.
For more information on the Asian citrus psyllid, visit its wikipedia page.
Some source material for this post came from the Live Science / Yahoo News story ‘Incurable Disease Threatens US Citrus Crop’ by Marc Lallanilla
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