How to save the world’s orange groves

CITRUS-GREENING disease is a bacterial infection of citrus-fruit trees, spread by insects called psyllids. It was first recorded a century ago, in China, and it has since spread widely. It can be extremely harmful. Within a decade of its arrival in Florida, for example, it had wreaked $4.6bn-worth of damage and reduced yields by 74%. If its spread continues, says Georgios Vidalakis of the University of California, Riverside, who directs California’s Citrus Clonal Protection Programme, citrus fruits risk becoming niche products.