Citrus greening is "the most serious threat that the Florida citrus industry has ever faced," according to the U.S. Department of Agriculture. The bacterial disease, which tends to turn fruit green after ripening, is spread by the Asian citrus psyllid insect. The devastating disease has infected an estimated 80 percent of Florida's citrus trees, and it has contributed significantly to the 60 percent reduction in the state's harvest of oranges and grapefruit since its peak in the late 1990s.
Now there may a way to fight back. Southern Gardens Citrus has engineered a version of the Citrus tristeza virus to attack the bacterium that causes citrus greening. The virus has been modified to carry a defensin protein found in spinach. When citrus greening bacteria come into contact with the protein, it kills them by perforating their cell walls, causing their contents to leak out. The company inoculates against the bacteria by grafting branches containing the genetically enhanced virus onto other trees. The virus then flows into the trees' vascular system, where it encounters and kills the bacteria.
In February, Southern Gardens Citrus applied for a permit for the environmental release of the virus. The Department of Agriculture is expected to allow Florida citrus growers to start using the virus in early 2019, according to Politico.
Florida growers hope that since the genes of the trees themselves are not being changed, anti-science groups will not damn the oranges and grapefruit from inoculated trees as Frankenfruit. But the public comments posted at Department of Agriculture's website suggest the bioluddites are not about to stand down.