Quarterly Reports

2nd Quarter: 2021

April - June

Tracking homeowner participation in residential buffer treatments

The Operations and Science Subcommittees of the Citrus Pest and Disease Prevention Committee (CPDPC) have both regularly dedicated time to reviewing the huanglongbing (HLB)/Asian citrus psyllid (ACP) regulatory program to ensure that actions continue to be scientifically valid and cost-effective. Most recently, homeowners refusing insecticide treatments for backyard citrus on properties near commercial groves became an area of focus for the Operations Subcommittee. DATOC was asked to review treatment, refusal, and host presence/absence data to determine what could be gleaned from the information. We reviewed areas of concern in Hemet and Ventura and found that, on average, insecticides were applied to 67% of the properties with citrus within 250 m of a commercial grove. For properties which directly border a grove, this number dropped to 65%. The average lot size treated in both areas was about ¾ of an acre; the median was less than ½ an acre. The Operations Subcommittee has requested our conclusions next be presented to the Science Subcommittee for review.

Assessing the regulatory program in Southern California

A broader set of program activities has been under review by the Science Subcommittee. DATOC has been supporting this review with a variety of analyses, including environmental suitability for ACP growth in different areas, disease modeling projects, and reviews of surveyed areas and estimated disease incidence in CA. Most recently, we proposed an alternative methodology for advancing the review. Specifically, we proposed the Subcommittee utilize a two-step approach to first identify the connections between program activities and their likely benefits, and second to identify the best- and worst-case scenarios of ceasing or continuing those activities. This report was presented to the Science subcommittee in April.

Comment on the continuation of the CPDPC

At least once every four years, the California Department of Food and Agriculture (CDFA) is required to hold public meetings to receive comments from the citrus industry and the public regarding whether the CPDPC is fulfilling its intended purposes. These meetings were held in May and June 2021, and DATOC provided a written comment detailing our interpretation of how the structure of the Committee’s approach to HLB/ACP management has impacted the success of disease management efforts in the state.

Detection of CLas in different tissue types

A continuing challenge in California’s efforts to detect and eradicate HLB is the difficulty inherent in detecting a bacteria distributed heterogeneously throughout its host. To this end, DATOC was asked to provide analytical support to a Citrus Research Board-funded project led by Subhas Hajeri from the Citrus Pest Detection Program and Lucita Kumagai from CDFA; this project was designed to compare the probability of HLB detection in trees in Southern California using different tissue types, incorporating possible confounding effects such as tree size or citrus variety. The first round of this support work was completed in June

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