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DATOC Projects

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Evaluating the size of delimitation zones

Project status: 

Status

Authors:

Dr. Robin Choudhury

DATOC was asked to review available data and determine if the initial 50 m treatment radius for a single ACP detection in residential areas of generally uninfested counties is sufficient.

Final report (if available):

Proposed approach for assessing the value of CPDPD activities in Southern California

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Evaluating buffer treatments in the context of refusal rates

Project status: 

Status

Authors:

Dr. Robin Choudhury

At the April Operations Subcommittee meeting, it was requested that DATOC review available data to determine what could be gleaned from the information with regards to program efficiency and/or how buffer treatments are being done.

Final report (if available):

Overview of ACP Trap Technology Research

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Optimizing residential insecticide applications for commercial grove protection

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Insecticide Treatments in Santa Clara

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Environmental suitability of the San Joaquin Valley in relation to trap servicing interval

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Criteria for reducing the delimitation radius

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Areawide Management Strategy

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Equitable and effective transport quarantines

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Buffer treatments efficacy

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Treatment area recommendation

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Hand cleaning bulk citrus

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Transovarial transmission of CLas

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Managing transportation risk

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Recommended sampling plan

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Evaluating exposure to HLB

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Growth of disease incidence in Southern California

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Recommended grower responses to HLB

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Seasonality of Ct Values in CA plant samples

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Exposure on repeat properties

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Density of new infections

Project status: 

Status

Authors:

Dr. Robin Choudhury

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.

Final report (if available):

Early Detection Technology Guidelines

Project status: 

Status

Authors:

Dr. Robin Choudhury

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

Final report (if available):

Hot Spot Cluster Analysis

Project status: 

Status

Authors:

Dr. Robin Choudhury

Dr. Dave Bartels of the USDA has previously provided cluster maps to various groups. DATOC will be assuming responsibility for the production of these maps to provide the CPDPP committees with on-going analysis of the epidemic, to help with resource allocation decisions

Final report (if available):

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