Epidemiology of sharka disease in Spain

Abstract

PPV was first detected in Spain in 1984 in Japanese plum (Prunus salicinaLindl) cv. Red Beaut and spread very quickly to other Japanese and European plums and apricot cultivars but left peach cultivars unaffected. In the years following the detection of PPV, the predominant aphid species visitingPrunusorchards in Mediterranean areas wereAphis gossypiifollowed byAphis spiraecola, the latter being the main aphid species found at present. Both species are considered to be the main vectors of PPV in Spanish earlyPrunusgrowing areas. Spatial analysis of the spread of PPV‐D in Japanese plum and apricot trees confirmed the lack of significant association between immediately adjacent trees. The observed spatial pattern of sharka suggests a lack of movement of PPV‐viruliferous aphid vectors to immediately adjacent trees and indicates their preferential movement to trees several tree spaces away. PPV‐D is the only type currently present in Spain, with the exception of a PPV‐M outbreak that was detected in and successfully eradicated from Aragón in 2002. The short‐distance spread of PPV‐M infection occurred as far as 12 m along the rows of peach trees. However, PPV‐D has not been observed to spread through peach cultivars, despite being grown in the vicinity of heavily infected plots of apricot or Japanese plum trees.