A deadly plant disease, huanglongbing (HLB), has been spreading throughout the U.S.’s citrus groves from Florida to California over the past decade, costing farmers and others billions of dollars. Some worry it may wipe out the American orange juice industry. Although scientists are trying to slow the spread of this disease, there may not be an easy solution, Anna Kuchment writes in a feature article published in this month’s Scientific American.
HLB is caused by bacteria carried in the salivary glands of the Asian citrus psyllid, a gnat-size, invasive insect. As the psyllid feeds on leaves, the bacteria infiltrate the plant’s circulatory system and lead to blockages that disrupt the flow of nutrients from the leaves to the roots. As a result of this bacterial invasion, first detected in the U.S. in 2005, HLB has cost the state of Florida alone $4.54 billion and more than 8,200 jobs.
Scientists are trying various approaches to slow HLB’s spread, including importing wasps from Asia to prey on the psyllids, which has had some success in Florida and California. Yet many think the best long-term solution will be genetic engineering, and scientists have already inserted HLB-resistant genes from spinach plants into citrus trees. Some are now experimenting with genes that would repel the insects, though any genetic modification would require adequate regulatory approval and public acceptance, Kuchment notes, leading to concerns that a solution may not arrive in time to save the citrus industry in the U.S.