Completed Projects

Criteria for reducing the delimitation radius

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.

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Operations SubCo

Completed:

Project Team

Early Detection Technology Guidelines

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

Origin:

Internal Deliberations

Completed:

Project Team

Areawide Management Strategy

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.

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Operations SubCo

Completed:

Project Team

Density of new infections

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.

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Operations SubCo

Completed:

Project Team

Exposure on repeat properties

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.

Origin:

CPDPC

Completed:

Project Team

Seasonality of Ct Values in CA plant samples

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

Origin:

Internal Deliberations

Completed:

Project Team

Recommended grower responses to HLB

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.

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Outreach Subco

Completed:

Project Team

Growth of disease incidence in Southern California

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.

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Operations SubCo

Completed:

Project Team

Recommended sampling plan

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.

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Internal Deliberations

Completed:

Project Team

Equitable and effective transport quarantines

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

Origin:

CPDPC

Completed:

Project Team

Managing transportation risk

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

Origin:

CPDPC

Completed:

Project Team

Transovarial transmission of CLas

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

Origin:

CPDPC

Completed:

Project Team

Hand cleaning bulk citrus

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.

Origin:

Internal Deliberations

Completed:

Project Team

Treatment area recommendation

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.

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Internal Deliberations

Completed:

Project Team

Buffer treatments efficacy

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

Origin:

Internal Deliberations

Completed:

Project Team

Time series analysis of ACP

The presence of ACP in California has been tracked by various programs and projects for several years. This analysis will construct a time series for various California regions since the start of these activities.

Origin:

Internal Deliberations

Completed:

Project Team

Evaluating exposure to HLB

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

Origin:

CPDPC

Completed:

Project Team

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DATOC is sponsored by the Citrus Research Board and the California Citrus Pest and Disease Prevention Program.