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Citrus Disease Threatens California Fruit Growers

Air Date: Week of
Nymphs of the citrus psyllid, which spreads HLB or yellow dragon disease (American Phytopathological Society)

In parts of China, citrus fruit can no long be grown, due to a disease spread by plant lice that kills the trees. That disease has been creeping across the warmer regions of the United States and recently reached California, where it is now striking widespread fear. Ingrid Lobet reports.


GELLERMAN: From the Jennifer and Ted Stanley Studios in Somerville Massachusetts, it’s Living on Earth. I’m Bruce Gellerman. An incurable disease that attacks citrus trees has devastated orchards in Florida. Since it was first detected in 1998, more than 70 million orange, lemon, lime and grapefruit trees have been infected, resulting in nearly four billion dollars in damage and the loss of 66 hundred jobs.

The disease, carried by a tiny insect, has since spread to other southern states and now to southern California, where officials are scrambling to protect the state’s precious groves and backyard trees. Living On Earth’s Ingrid Lobet reports.


LOBET: I’m standing in a tidy, middle class neighborhood in Hacienda Heights, a city in Los Angeles. I’m witnessing something you don’t see every day. Hector Verduzco is sucking insects into a glass vial.


Hector Verduzco of the California Department of Food and Agriculture removes citrus psyllids from a Hacienda Heights lemon tree for DNA analysis
(photo: Ingrid Lobet)

LOBET: Verduzco, who works for the California Department of Food and Agriculture, fixes his gaze on the newest growth on a bushy front yard lemon tree. He sucks a small tube, which pulls a small insect off the branch and into a jar.

GALINDO: Right there happens to be an adult.

LOBET: Tina Galindo spearheads the attack on this insect, the citrus psyllid, in southern California.

GALINDO: So yeah, that is an adult; you can see how small, it's about the size of an aphid. They really like to feed on the new tender growth that is coming out.

LOBET: These insects are all over Los Angeles now. Experts estimate there may be a million of them. The insects are one thing but the real problem is when they spread huanglongbing, also known as HLB or yellow dragon disease, which kills trees slowly. A few weeks ago, for the first time in California, the disease was found. Right near this house in Hacienda Heights, one of Galindo’s crews gathered an insect sample, sent it to the lab, and it came back positive.

GALINDO: It was a lemon. But it had a lot of grafts on it.

LOBET: Did you hear that? She said the infected lemon tree had a lot of grafts on it.

GALINDO: We call it a cocktail tree.

LOBET: It’s not uncommon for people to graft budding branches of tangerine or lime onto say, a lemon tree here. Sometimes neighbors trade branches. The state estimates more than half of residential properties in southern California have citrus trees. But now Galindo says she wants to get the word out that people should keep their buds and shoots to themselves.

GALINDO: For sure you don’t want to be sharing your grafts with other people in the area.

LOBET: What’s at stake is California’s two billion dollar citrus industry. Authorities say people in a quarantine zone where the disease was found should not share fruit and shouldn’t give young trees to each other, either, a message sent in this USDA public service announcement.


VOICEOVER: When you transport a citrus tree, you’re playing a very risky game with the future of all of America’s citrus. Imagine orange groves, tangerines, lemons, gone forever…

LOBET: But that message is tame compared to this one.

[Menacing music]

[VIDEO: The tree eventually dies and there is no cure for the disease…]

LOBET: This video was produced in 2009, when the citrus psyllid and HLB disease had entered Florida. Growers there warned the rest of the country to learn from their misfortune and be more vigilant.

[VIDEO: The Asian citrus psyllid has already spread HLB around Asia, India, parts of the Middle East, Belize, Mexico and south and central America…]

In California, more than half of residential lots have citrus trees. A single case of Citrus Greening disease was found here, in the city of Hacienda Heights. (Ingrid Lobet)

LOBET: To slow the spread of HLB, infected trees are destroyed. Trees that merely have the insect are sprayed with two insecticides, a pyrethrin to kill adults and the neonicotinoid imidacloprid. That gets into the plant’s system and poisons young insects as they feed.

BATKIN: Unfortunately for the organic growers, we do not have an organic certified treatment that works very well.

LOBET: Ted Batkin is president of the Citrus Research Board in Visalia, California. He also happens to be an organic grower.

BATKIN: We have to really kind of step back and say – maybe lose our organic certification for a year or so, in order to get this disease and population in control so we can survive in an organic environment.

LOBET: The alternative, Batkin says, could be much worse.

BATKIN: There are just parts of China and Asia where you just cannot grow citrus.

LOBET: Americans, Batkin says, aren’t yet feeling the full impact of the damage that’s already been done in Florida. But they will, as the supply of fruit and juice dries up.

BATKIN: We are seeing approximately a ten to 15 percent decline per year in tree health. If you kind of look at the statistics of how many oranges have been put into juice production in Florida, there is this kind of continuous decline.

LOBET: The citrus psyllid and the disease have hit Georgia, South Carolina, Texas and Louisiana, as you can hear in this LSU ag center news report.

[REPORTER: The Asian citrus psyllid has been found in 5 parishes in Louisiana, it can devastate the state’s citrus crop through transmission of a disease.]

LOBET: But so far Arizona, Mississippi and Alabama have only the bugs. They’ve remained disease free.


LOBET: Back in Hacienda Heights with the state inspectors, Dolores Escalante, comes out of her home to talk about her beautiful lemon tree.


VOICEOVER: This tree is from my native land. I’m from Yucatan, in Mexico. Some friends from there brought the seeds for this variety, so we can cook with the right ingredients. All year round it gives us lemons.


LOBET: Watching the state agents whisk away the insects they collected to send to the lab, she seems worried.


VOICEOVER: Just imagine if we have to take out this tree, after all the effort to care for it.

LOBET: And she probably speaks for growers and residents across the warmer parts of the United States where citrus grows. For Living On Earth, I’m Ingrid Lobet.



More about HLB or Citrus Greening

California Citrus Research Board

California Department of Food and Agriculture Psyllid page


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