DETECTION CHARACTERIZATION EPIDEMIOLOGY AND ERADICATION OF PLUM POX VIRUS MARCUS TYPE IN SPAIN
N. Capote, M.A. Cambra, P. Botella, M.T. Gorris, M.C. Martínez, A. López-Quílez, M. Cambra
Sharka disease caused by Plum pox virus (PPV) is widespread in a number of Spanish stone fruit-growing areas; only the common Dideron type (PPV-D) is prevalent. Systematic surveys of field and packing houses were conducted in 2002 for detection of the aggressive Marcus type (PPV-M). The focus of PPV-M was an infected cv. Royal Gem peach (Prunus persica L.) orchard in Zaragoza province (Ebro Valley, Aragón). Over three years, the virus has spread from this orchard to distant plots by means of grafting of infected plant material and to neighbouring plots by aphid transmission. Serological and molecular analyses of symptomatic trees and fruits confirmed the presence of PPV-M in these plots and segregation of the initial viral population into three serogroups and seven different haplotypes as a consequence of host/individual change or vector transmission. Not only did peach cv. Royal Gem become infected, but also cvs Calante and Gladys, in 4 orchards with a total area of 19.5 ha. Spatial analysis of the spread of infection showed a compound contagion process with long-range (up to 150 meters) and short-range movements to adjacent trees in the same row. The main aphid vectors present in the area were Aphis spiraecola Pagenstecher, A. gossypii Glover and Myzus persicae Sulz.. Experimental aphid transmission assays showed that the introduced PPV-M isolate was more efficiently transmitted to other peach cultivars from GF305 peach seedlings, rather than to P. persica cv. Gladys young trees. All tree blocks infected with PPV-M were uprooted. Eight years later (2010) no more PPV-M has been detected in commercial Prunus orchards in the area suggesting successful eradication.