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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Research Project #439524

Research Project: California Citrus Tristeza Virus Survey

Location: Crop Diseases, Pests and Genetics Research

Project Number: 2034-22000-013-013-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2020
End Date: Jun 30, 2022

Objective:
The objective of this research project is to develop a statistically valid estimate of the the incidence of citrus tristeza virus-infected citrus trees in commercial orchards in California and determine the prevalent strains of CTV. This data is needed for an Environmental Assessment and Environmental Impact Statement to support a permit for field release of genetically engineered CTV in California citrus.

Approach:
Commercial citrus orchards over 20 acres in size will be selected from 12 major citrus-growing counties and 50 hierarchical subsamples per orchard will be collected and dessicated by silica gel in the field. Samples will be transported to the lab, rehydrated and tested by broad spectrum polyclonal Citrus Tristeza Virus (CTV) and MCA13 antisera. CTV-positive samples will be subjected to strain discriminating primer/probes by RT-qPCR to determine prevalent strain(s) present. RT-PCR and sequencing of some 5' genome regions may be required to confirm genotype. The number of orchards to sample is based on the proportion of citrus acres per county. Sample transport is covered by CDFA movement permit that allows testing for pathogens except huanglongbing (HLB).