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Kern County citrus growers are extremely anxious about the looming threat of citrus greening disease, known as huanglongbing in China, where it originated. The illness isn't harmful to people or animals, but it kills fruit trees and has decimated the citrus industry in Florida. The disease is carried on an insect called the Asian citrus psyllid. Not every psyllid is a carrier, but the disease cannot spread without the pest, which transmits it by feeding on the liquid inside citrus leaves.

The Central Valley's citrus industry is hailing a potential breakthrough in the fight against a so-far incurable bacterial disease threatening to wipe out Kern's mandarin, orange and lemon groves.

A researcher at the University of California, Riverside has identified a naturally occurring protein compound that appears to not only treat trees infected with the disease but also immunize them against it.

The material is a peptide found in Australian finger lime trees, which naturally resist the disease. The researcher behind its discovery, UC Riverside geneticist and molecular biologist Hailing Jin, said the treatment has proved effective in the lab and in small citrus trees growing in a greenhouse.

Further testing will be required before it can be determined whether the peptide is widely effective and can be commercialized for use by local growers. It's unclear how soon that might happen but Jin said the process could take years.

The treatment's regulatory approval process could be accelerated by the Cambridge, Mass.-based company that's secured an exclusive worldwide license to the peptide, Invaio Sciences.

MOTTLED THREAT

Citrus greening disease, better known by its Chinese name, Huanglongbing, or HLB, has devastated Florida's citrus industry. It's been found in Los Angeles and Orange counties but not in the Central Valley, though people in the industry say it's a matter of time before it arrives in Kern.

Only one creature is known to carry HLB: a tiny, mottled-brown insect called an Asian citrus psyllid. The moth-like insect has been spotted all over Bakersfield and other parts of the state but no specimens carrying the disease have been found in the Central Valley.

Money for Jin's research was contributed by Exeter-based trade group California Citrus Mutual, whose president and CEO, Casey Creamer, called the discovery exciting and a potential breakthrough. But he emphasized the industry is exercising cautious optimism.

'YOU NEVER KNOW'

"A lot of things work in the lab and don't work out in the field," Creamer said. He noted other researchers are working to attack HLB using a variety of approaches, adding: "You never know what's going to work until it actually does."

He said efforts to protect the Central Valley from HLB have largely succeeded, though there's some concern that the psyllid is turning up in Ventura County despite expanded quarantine areas.

"I think we've exceeded the expectations on how long we could manage keeping it out of the commercial groves," Creamer said. "I'm still (optimistic) that we're going to be successful in this battle. The suppression of the psyllid is a sign of that."

NEXT TO WATER

Delano area-based grower Matt Fisher, a fourth-generation farmer, said he was aware of Jin's peptide and that he considers it "one of the most promising pieces of research that I've heard about and seen.

"It appears to be something that can really help us turn the corner," he said. "This HLB is, other than water, our single-greatest threat in this business."

Jin, reached by phone Friday, said she's been working to cure HLB for close to 10 years. When she learned certain wild citrus trees tolerate HLB, she focused on isolating the genes responsible.

She made of list of candidate genes and then a screening system. She had to substitute a bacterium related to HLB because the one carried by the psyllids is hard to cultivate in a lab.

GREEN, HEALTHY

The University of California, Davis contributed sets of infected sweet orange trees, lemon trees and root stalks. The ones treated with the peptide improved dramatically in experiments that extended up to 1½ years, Jin said.

"The new flesh and the new leaves are green and healthy," she said.

She said the treatment, also a vaccine, can withstand temperatures of up to 130 degrees — an important characteristic that other antibiotics fail to achieve. It enters a tree's system after being sprayed, she said.

Her hope now is the U.S. Environmental Protection Agency approves the finger lime's peptide before it's too late.

"I hope we can be fast enough before the disease … reaches the Central Valley," she said.

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