The disease, spread by the Asian citrus psyllid, a small bug that was first identified in California in 2008, has no known cure, the Los Angeles Times reported. A sick tree growing in a yard in Hacienda Heights was identified as having huanglongbing on March 30.
Agricultural officials believe the disease may have come from a graft of pomelo grapefruit on the lemon tree. Now, they are trying to trace the graft back to its source and hoping to slow the spread of the disease by destroying diseased trees and mandating spraying around them.
Wingtack Wong, who helps run a family business, Temple Garden Center in El Monte, worked on the agricultural commission in Guangzhou province in China in the 1960s. That was when huanglongbin, a Chinese name that means "yellow dragon disease," arrived.
"One yellow leaf tuned into an entire yellow tree, the fruit shriveled up and slowly the rest of the trees turned yellow, and then it was all gone," he told the Times, describing the impact.