Epidemiology of Citrus tristeza virus (CTV) in Citrus Varieties Cultivated Under Plastic Net Covers

Abstract

The spread of Citrus tristeza virus (CTV), as well as the evolution of aphid species, was followed from 1997 to 2001 in two adjacent plots of 120 Marisol and Oronules early Clementines planted in 1994. One plot was covered with a plastic net in 1997 and the other remained uncovered in open field. The use of partially closed plastic net covers significantly reduces the spread of CTV but it does not prevent reinfection if there are already infected trees under the covering. The percentage of CTV-infected trees in the open field increased from 17.5% (1997) to 52.5% (2001) and from 16.7% to 30.0% under net covering in the same period. There is a relationship between old infected trees and recently infected trees but only in the same row under plastic net covering. Aphis spiraecola population is increasing to the detriment of A. gossypii in Valencia.