Survey estimates of the incidence and diversity of Citrus tristeza virus in California

Surveys were conducted to assess Citrus tristeza virus (CTV) in California. Orchard surveys in central California during 2009 to 2013 estimated CTV incidence from 0.05% to 2.9%. Similar surveys in Ventura, Riverside, San Bernardino, and San Diego Counties in 2020-22 estimated CTV incidence from 6.3% to 34.9% while CTV was rarely found in the other five counties surveyed. T30 comprised over 95% of CTV detected alone or in mixtures with other strains in southern California and constituted 59% of 550 CTV accessions maintained in Tulare, California. VT, RB, and S1 genotypes were also found but T36 was rarely detected. No evidence of CTV-induced economic damage was noted except for occasional CTV quick decline on sour orange rootstock.