Inside Santa Barbara’s fight to save citrus trees

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The Asian Citrus Psyllid. Photo: CDFA


There’s a pest attacking California’s citrus. The Asian citrus psyllid (ACP) is a tiny, flying insect that transmits a bacterial disease called huanglongbing, or HLB. It’s also known as citrus greening disease, and it’s fatal for citrus trees.

To protect against these insects and avoid the mass citrus die-off Florida has experienced, the California Department of Food and Agriculture has begun implementing a statewide treatment program. It involves applying two insecticides:

  • Tempo, a contact insecticide for controlling the adults and nymphs of ACP, will be applied from the ground using hydraulic spray equipment to the foliage of host plants.
  • Merit, a systematic insecticide for controlling the immature life stages of ACP, will be applied to the soil underneath host plants.

Currently in Santa Barbara County, the CDFA is treating any citrus tress within a 400 meter radius of commercial citrus farms. That includes a large part of Carpinteria and smaller sections of Montecito and Santa Barbara.

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According to Victoria Hornbaker, citrus program manager for the CDFA, it can take up to five years for the disease to manifest itself in a tree. That means that some trees in the county may already be affected.

“This could essentially wipe out all of your commercial citrus in Santa Barbara,” she said. “If an ACP lands and feeds, it will contract the bacteria. Then, that ACP will fly to another tree and feed there, and spread that bacteria from its mouth parts into the other tree.”

Because of this, the CDFA has transitioned from responding to individual finds to creating “psyllid management areas,” 400 meter buffer zones surrounding commercial citrus.

The program is voluntary. If homeowners and residents don’t want the CDFA to treat their property, they can opt out of the program by contacting the department. Beekeepers are especially worried. The Environmental Protection Agency recently found at least one neonicotinoid insecticide is harmful to bees when ingested. According to Hornbaker, the insecticide is applied to the soil rather than the foliage, meaning bees are unaffected. Many beekeepers, however, argue that if the insecticide makes its way into the roots and up into the entire plant, it can still make its way into the bee.

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A citrus tree affected with HLB. Photo: CDFA

“It’s hard to gauge the worth of one agricultural commodity over another one,” she said. “I think it’s worth doing what we can to protect citrus and protect pollinators at the same time.”

The CDFA does not offer the option to treat organically. “I understand that some people are uncomfortable with conventional chemicals,” Hornbaker said, but she hopes those who opt out will decide to treat their property themselves with whatever method makes them comfortable.

If the disease creeps into the county Hornbaker said the department will be very aggressive in its response.

“Trees with HLB will be pulled out of the ground and destroyed to protect neighboring trees,” she said. “At that point, we may take mandatory action to treat for the ACP populations, like we’re doing in Los Angeles County.”

What do beekeepers think? Listen to our interview with Don Cole, a Santa Barbara beekeeper.