Spread of citrus tristeza virus in central California

Authors: Yokomi, Raymond - Ray; Sisterson, Mark; HAJERI, SUBHAS - Central California Tristeza Eradication Agency

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2020
Publication Date: 12/30/2021
Citation: Yokomi, R.K., Sisterson, M.S., Hajeri, S. 2021. Spread of citrus tristeza virus in central California. Phytopathology. 110:S2.1. https://doi.org/10.1094/PHYTO-110-12-S2.1.
DOI: https://doi.org/10.1094/PHYTO-110-12-S2.1

Interpretive Summary:

Technical Abstract: Citrus tristeza virus (CTV) in California is regulated by a State Interior Quarantine where, in abatement districts, roguing of CTV-infected trees occur based on reactivity to MCA13, a strain-discriminating monoclonal antibody. To determine the efficacy of this program on spread of MCA13 isolates, CTV surveys were conducted in abatement plots with mandatory aphid control and non-abatement plots under normal pest management practices. In abatements plots, incidence of CTV from 2008 to 2018 increased by an average of 3.9%, with only two MCA13+ trees detected. In contrast in non-abatement plots, incidence of CTV increased by an average of 4.6%, between 2015 and 2018. Increase in non-MCA13 isolates was eleven times greater than that of MCA13 isolates and were more randomly distributed suggesting primary spread. In contrast, MCA13 isolates were more aggregated suggesting some secondary spread had occurred. These results suggested that spread of MCA13 isolates was limited by a combination of tree removal and aphid vector suppression. Trees with MCA13 CTV were comprised mostly of VT genotypes with some mixtures with T30 genotypes. Despite the presence of VT strains, all CTV-infected trees were asymptomatic.