Incidence and distribution of ‘Candidatus Phytoplasma prunorum’ and its vector Cacopsylla pruni in Spain: an approach to the epidemiology of the disease and the role of wild Prunus

Abstract

‘Candidatus Phytoplasma prunorum’ is the causal agent of the European stone fruit yellows (ESFY) disease. This phytoplasma affects wild and cultivated species of Prunus to different degrees, depending on their susceptibility. ‘Candidatus Phytoplasma prunorum’ is present in the four regions of Spain surveyed in this study (Aragon, Catalonia, Extremadura and Valencia) with a variable incidence. Results showed that ‘Ca. Phytoplasma prunorum’ was detected in all of the cultivated Prunus species studied, except P. avium and P. dulcis, and was widespread in Spain. The most affected species was P. salicina, with symptoms including early bud break and blooming, leaf curling and yellowing, collapse, and a major decrease in production. In some plots in the Baix Llobregat area of Barcelona province (Catalonia), the incidence of ESFY on P. salicina was as high as 80%. The insect vector, Cacopsylla pruni, was present in all four of the regions studied, with the highest captures in yellow sticky traps in Catalonia on P. mahaleb and in Extremadura in peach orchards. In Baix Llobregat, large populations of C. pruni were present on infected P. mahaleb bushes, and with high infection rates. This was a key factor in the local pathogenic cycle that caused a major ESFY outbreak in the nearby P. salicina orchards. In the Ebro valley (Lleida and Aragon) and Valencia, the surveys showed very low incidences of the disease and low C. pruni populations.

Cacopsylla pruni in Poland and its significance as a vector of ‘Candidatus Phytoplasma prunorum’

“…The C. pruni occurrence was observed in plum orchards primarily in the spring (March-May), but not in the summer (June-July). Similar results were obtained in the studies conducted in other countries, e.g., in France and Spain (Labonne, Lichou, 2004;Thébaud et al, 2009;Sabaté et al, 2015).…”

“…prunorum', the degree of infection by this pathogen can be estimated at between 1.9% and 5.3%, or, if we also include specimens collected from blackthorn (53) and coniferous plants (1), the infection rate was between 1.5% and 4.2%. These values were lower than those obtained for C. pruni in the apricot orchards in Moravia, or in stone fruit orchards in several regions of Spain, where the rate of infection in the spring period reached tens of percent (Fialová et al, 2004;Sabaté et al, 2015).…”

“…Ph. prunorum' has been found in the countries of the Mediterranean Basin (Thébaud et al, 2009;Cieślińska, Morgaś, 2011;Steffek et al, 2012;Sabaté et al, 2015).…”

Transmission of ‘Candidatus Phytoplasma pyri’ by naturally infected Cacopsylla pyri to peach, an approach to the epidemiology of peach yellow leaf roll (PYLR) in Spain

“…Consequently, it would seem that adults of C. pyri only feed occasionally on peach, especially in autumn when the insects fly out to overwinter and stop temporarily in nearby peach trees. Other potential vectors were discarded because they were found in very low numbers or not infected by this phytoplasma, including C. pruni that was not captured in this study or previously in this area (Sabaté et al ., ). The percentage of pear psyllids carrying the PD phytoplasma showed a seasonal trend through the year, which coincides with the seasonal detection of ‘ Ca .…”

“…Furthermore, the frequency of ESFY appearance on Prunus persica in Lleida is very restricted, C. pruni is not present and ‘ Ca . Phytoplasma pyri’ is in almost every pear orchard (Garcia‐Chapa et al ., ; Sabaté et al ., ). All the infected peach trees were positive for ‘ Ca .…”