CLas-Positive ACP Confirmed in Ventura County

Brian GermanCitrus, Fruits & Vegetables, Industry

An Asian citrus psyllid (ACP) carrying Candidatus Liberibacter asiaticus (CLas) has been identified on a residential property in Ventura County. The confirmation comes from the Citrus Research Board’s Jerry Dimitman Laboratory and was reported by the Citrus Pest & Disease Prevention Program. This CLas-positive ACP sample, comprised of 12 adult psyllids from a residential citrus tree in Santa Paula’s Southwest area, was initially collected during the Multi-Pest Risk Survey on September 6. It was later confirmed as positive for CLas on September 19.

CLas-positive ACP
Adult Asian citrus psyllid on a citrus leaf.
USDA/ARS Photo by David Hall

This marks the first instance of a CLas-positive ACP being found in Ventura County. Fortunately, no Huanglongbing (HLB) quarantine zone will be established due to the detection. The California Department of Food and Agriculture (CDFA) is actively conducting surveys and collecting samples as per the ACP/HLB Action Plan. Samples will be taken from the original property and all HLB host plants located within a 250-meter radius.

Despite the concerning discovery, HLB has not been detected in any citrus trees in Ventura County as of now. The discovery does however emphasize the importance of maintaining effective control measures for ACP populations to prevent the spread of the disease. A CLas-positive ACP can often precede the detection of an HLB-positive tree.

During the initial collection on September 6, no nymphs were observed. However, in subsequent resampling efforts this week, CDFA collected 15 nymphs from the same property but on a different host plant. CDFA teams are actively conducting surveys for additional adult or nymph psyllids as part of the survey.

The CLas-positive ACP detection is unrelated to the research conducted in Southern California last year. This research was part of a program funded by the HLB Multi Agency Coordination Group and conducted by various universities. The laboratory tests in these studies differ from the federally approved testing methods required by CDFA labs, making this the first recognized CLas-positive ACP detection by CDFA.

While treatment is not mandatory for commercial growers in the affected area, local growers interested in proactive measures to protect their groves or with questions can contact Ventura County Grower Liaisons Sandra Zwaal or Cressida Silvers.

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Brian German

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Ag News Director, AgNet West