According to the United States Department of Agriculture (USDA), citrus greening or yellow dragon disease, is believed to be a bacterial disease which originated in China in the 1900s. It is spread by two species of psyllid insects, including Asian citrus psyllids. There are three strains of the bacteria; however, it is not harmful to humans. Still, it will be devastating for the future of citrus crops if it cannot be stopped.
Yellow dragon disease first hit Florida’s citrus growers in 2005. The New York Times reports this year they’ve harvested the worst crop to date with some groves losing up to 40% of their crop. “The long and short of it is that the industry that made Florida, that is synonymous with Florida, that is a staple on every American table, is totally threatened,” Senator Bill Nelson told the New York Times.
Other than tree removal, there is no effective control once a tree is infected and there is no known cure for the disease. Infected trees may produce misshapen, unmarketable, bitter fruit. Citrus greening reduces the quantity and quality of citrus fruits, eventually rendering infected trees useless. In areas of the world affected by citrus greening, the average productive lifespan of citrus trees has dropped from 50 or more years to 15 or less. Once infected, trees in the orchard die within 3 – 5 years and require removal and replanting.
Not only has this yellow dragon disease adversely affected Florida’s citrus crop, it has also been detected in California and may be headed to Hawaii. Hawaii is at risk due to the large population of the non-native Asian psyllid, a gnat-sized insect, which has been detected on the island of Maui. Once a psyllid becomes infected, it remains infected for life. The only way a psyllid becomes infected is when it feeds on an infected tree. As long as no infected citrus plants are brought into Hawaii, their citrus crop should remain safe.
Citrus greening has also been reported in countries in Africa, Asia and South America. To date, it has not been reported in the citrus-producing regions of Australia or the Mediterranean countries.