Since 2018, the Science Subcommittee has wrestled with how to determine whether Citrus Pest and Disease Prevention Division’s (CPDPD) regulatory activities are, or are not, supported by data, and how to judge if, when, or how activities should be restructured. We present here an process that could be utilized to move the discussion forward.

DATOC was asked to review available methods of ACP trapping and recent research on the subject.
After discussions with the DATOC expert panel/review of the literature, we could not recommend any new technology for immediate utilization by the CPDPD, but there were a few options that could be tested experimentally.

An informative briefing providing context for a 2020 decision to cease treatments in certain areas of Santa Clara.

In the fall of 2020, the ACP-detection trapping program in the San Joaquin Valley was operated on a bi-weekly schedule, although the CDFA Action Plan dictates a monthly schedule. DATOC was requested to provide input on whether the program should shift to a monthly schedule or amend the Action Plan to indicate that bi-weekly trapping should be continued.

DATOC was asked to explore how the procedure for applying insecticides in residential areas (“buffer zones”) surrounding commercial groves under area-wide ACP control programs might be improved.

DATOC was requested to provide a report summarizing research done on Early Detection Technologies which was funded by the Citrus Research Board and HLB-MAC. The report is to include explanations of each technology, economic concerns, diagnostic accuracy, and more.

DATOC has been requested to analyze CDFA's program activities combating HLB in Southern California for efficiency and effectiveness.

This report proposes that the delimitation radius for tree surveys around an HLB+ tree be reduced from 400m to 300m. This change is suggested based on the geographic distribution of all trees confirmed to be positive for huanglongbing by March 2020, based on a methodology previously used by the CPDPC to make operational decisions.

DATOC has produced guidelines for citrus growers who choose to use an EDT (for example, detector canines) to screen their groves.

Residential buffer zones around commercial citrus can be treated by CDFA with insecticides to suppress Asian citrus psyllid populations only if 90% of growers in that region apply insecticides within a designated 3-week window. While useful, this threshold created logistical difficulties and a new criterion for treatment was explored.

The goal of this analysis was to understand how likely it is for a site with 1 HLB-positive tree to develop another HLB-positive tree in the future.

As a part of DATOC's report on exposure to CLas in Southern California residential areas, DATOC was asked to evaluate exposure over smaller geographic scales. We also evaluated the changes in infection density in the most recent detections.

There is no evidence thus far for seasonal patterns of Ct value variability from CA CLas+ plant samples.

DATOC compiled available research to help the CPDPC advise growers on how they should respond to an HLB find in or near their commercial grove. This was the basis of the "Best Management Practices in Response to Huanglongbing in California Citrus", approved by the CPDPC and published on CitrusInsider.org.

An analysis of the growth rate in new detections of HLB in Southern California, to help determine if a threshold has been reached beyond which current management practices are unfeasible.

The CDFA action plan previously called for sampling 25% of an orchard should HLB be found within 400m. Best available evidence indicated that would be inefficient. DATOC suggested an evidence-based replacement plan, which was approved in March 2019.

The industry should utilize geographically regulated areas to restrict ACP dispersal.

Analysis of transportation risk of CLas+ ACP between bulk citrus quarantine zones in California

A report released in December 2018 on vertical transmission of CLas from ACP parent to progeny.

Field cleaning by hand has not been shown to reduce the number of psyllids in bulk citrus bins or the potential risk of moving psyllids when the fruit is moved.

The DATOC expert panel feels strongly that the find of a single Asian citrus psyllid (ACP) in an area which is not generally infested and eradication is still being attempted should trigger a treatment area around the detection that is never less than a 400 m radius.

An analysis of critical factors which determine the efficacy of areawide buffer treatments mitigation of ACP/HLB risk for commercial groves.

Examination of the possibility to define a rigorous meaning for the word "exposed", as used in the California agriculture code, in relation to HLB