Ventura County detects first infected Asian citrus psyllid
By Ching Lee Citrus growers in Ventura County re- main vigilant after agricultural officials confirmed the region’s first finding of an insect pest carrying the huanglongbing bacteria, which kills citrus trees. The discovery is a concern because Ventura County remains the state’s top producer of lemons and grows other cit- rus fruits. The infected Asian citrus psyllid, which authorities confirmed on Sept. 19, was found in a residential citrus tree in the southwestern area of Santa Paula, ac- cording to the California Department of Food and Agriculture. It tested positive for Candidatus Liberibacter asiastius, the pathogen associated with huan- glongbing, or HLB, also known as citrus greening disease. Though the fatal disease has not been detected in any of the county’s citrus trees, finding an infected psyllid, which transmits the disease when it feeds on the plant, oftentimes is a precursor, “as it’s assumed the psyllid is actively feeding and/or breeding on nearby citrus plants,” said Keith Okasaki, CDFA regulatory manager for the Citrus Pest and Disease Prevention Division. HLB symptoms can often take a couple years to manifest after
the tree is infected, he added. “Hot trees are throughout San Diego, Orange and LA (counties), so it’s com- ing, if not already here,” said Ben Faber, University of California Cooperative Extension farm advisor for Ventura and Santa Barbara counties. Not every infected psyllid finding has resulted in trees testing positive for the disease. Okasaki noted in early 2021, an infected psyllid was found in the Fallbrook area of San Diego County, and that imme- diate area has yet to see an HLB-positive plant sample. However, a positive plant sample showed up in the Oceanside area later that year. “The frequency of this occurrence can vary and is not a sure thing for every case,” Okasaki said. Confirmation of an HLB-infected tree would trigger a mandatory 5-mile quar- antine around the find site. There is no known cure for HLB, which can kill a citrus tree within five to eight years. All commonly grown citrus variet- ies are susceptible. The only way to protect citrus trees from the disease is to prevent spread of the HLB pathogen by controlling populations of the vector and destroying infected trees. Since its discovery in Florida in 2005,
An adult Asian citrus psyllid, left, and yellow nymphs feed on a citrus tree’s leaves and stems, leaving behind a white, waxy substance. Psyllids carrying the huanglongbing bacteria can kill citrus trees.
HLB has decimated the Sunshine State’s citrus production, which has dropped by 90%, according to the U.S. Department of Agriculture. Considering the pest is now well es- tablished in Southern California, Ventura County grower Will Pidduck said finding one carrying HLB in the region comes as no surprise. “It’s not shocking by any means,” he said. “I’m surprised they hadn’t found one sooner. There’s just so many psyllids around. I think we’ve all been somewhat expecting it.” For now, Pidduck said it has been
business as usual on the farm, with lemon harvest completed for the year. As such, farms are not moving any fruit until winter harvest starts. He said growers continue to monitor their groves and apply foliar treat- ments to keep psyllid populations down, which have worked for years to prevent the disease from spreading to California commercial orchards. California confirmed its first finding of the Asian citrus psyllid in 2008 in San Diego County. HLB was first detected in Los Angeles County in 2012 and has since been found in Orange, Riverside, San
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October 4, 2023 Ag Alert 3
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