A Devastating Citrus Disease Finally Has A New Treatment

A disease that has devastated Florida citrus and threatens California crops may finally be tamed by a new treatment discovered by scientists at UC Riverside.

The disease, known as citrus greening disease, showed up in Southern California eight years ago. It's caused by a bacterium known as CLas, also called Huanglongbing or HLB, according to the university. It spreads through an insect called the Asian citrus psyllid. When a tree is infected, its growth is stunted, it develops lopsided, green fruits, and eventually it stops producing altogether.

The Asian citrus psyllid, pictured here, spreads the bacterium that causes citrus greening disease. (Mike Lewis/UCR)

Previously, there was no cure, so growers often resorted to spraying antibiotics or chemical pesticides to prevent infection.

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"There's also other methods that are non-chemical, where they actually have to wash these oranges or lemons and remove stems and leaves from the fruit," Riverside County Agricultural Commissioner Ruben Arroyo told KPCC/LAist.

But the disease was wreaking havoc on crops anyway.

The new treatment was discovered by UCR geneticist Hailing Jin. It's a compound found to occur naturally in a citrus relative known as a New Zealand fingerling lime. Jin traced the genes that give the fingerling lime its natural immunity and discovered that one of these genes produces the compound. After testing, Jin found the trees improved within a few months when they were treated by spraying their leaves or injecting them with the compound.

UCR says the treatment is easily manufactured, safe for humans and requires application a few times a year.

HERE'S MORE BACKGROUND ON CITRUS GREENING:

• California farmers and scientists race to combat a citrus disease infecting trees (LA Times)
• California expands local quarantine to halt citrus disease spread by aphid-like bug (LA Times)

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