- A gnat-sized insect known as the Asian citrus psyllid has been spreading a deadly plant disease through America's citrus groves. Early attempts to contain the disease, known as huanglongbing, have failed, and it has become a major threat to the U.S. citrus industry.
- Huanglongbing is caused by bacteria in the genus Candidatus Liberibacter, which Asian citrus psyllids carry in their salivary glands. The bacteria infiltrate plants' circulatory systems, which results in blockages that disrupt the flow of nutrients from leaves to roots.
- To slow huanglongbing, scientists have imported wasps from Asia to prey on the psyllids, among many other approaches. The best long-term solution may be genetic modification, which faces a long and costly road to regulatory approval and public acceptance.
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One day in 2005, just before Hurricane Katrina blew through Florida and devastated New Orleans, Susan Halbert stood before a pomelo tree on a farm outside Miami. Something about this tree did not look right. It seemed undernourished: its leaves were sparse, and its melon-size citrus fruit was lopsided. Yet all the other plants in the garden were thriving, and the woman who took care of them had carefully tended the pomelo with a fresh layer of fertilizer. “She clearly knew how to grow plants,” says Halbert, an entomologist for the Florida Department of Agriculture and Consumer Services (FDACS).
Halbert scrutinized the tree like a detective at a crime scene, mentally ticking off every condition she could think of. She ruled out root rot, which is caused by a fungus, because the tree showed none of the characteristic signs of decay. Next, she considered a viral disease known as citrus tristeza—Spanish and Portuguese for “sadness”—which affects trees that have been grafted. (Citrus growers often raise trees not from seeds but by inserting a branch from one tree into the bark of another.) The pomelo, however, had not been grafted. Eventually Halbert got to the bottom of her list to the most devastating disease of citrus plants in the world—huanglongbing, Chinese for “yellow dragon disease.”
This article was originally published with the title The End of Orange Juice.