Over the last three years, visual symptom assessment and PCR amplification were used to survey the occurrence of apple proliferation (AP) disease in low-intensity orchards in Agri valley, a major cultivation area of Basilicata region. The apple trees examined, whose scion cultivars were not determined and consisted mostly of local cultivars, were more than 20 years old therefore had been exposed to insect vectors for a long time. The survey revealed that a high percentage of trees were infected reaching more than 50% in some locations. The symptoms of diseased trees were generally mild and consisted of enlarged stipules, rosettes, witches’-brooms as well as basal witches’-broom-like growth arising from large roots. However, incidence and severity of symptoms in the aerial parts of affected trees were pronounced only in trees which had been heavily pruned in the previous dormant season. Specificity of the primers used and restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA sequences employing SspI and BsaAI restriction endonucleases showed that the trees testing positive by PCR were infected by the AP agent ‘Candidatus Phytoplasma mali’. The high incidence of AP infections in low-intensity orchards in Agri valley is likely associated with inappropiate vector control. The trees examined were not or rarely treated with insecticides. On the other hand, typical AP symptoms seem to be uncommon in commercial apple orchards in Agri valley, which are treated with standard insecticide programs. Although a few AP-affected apple trees grown in a low-intensity orchard in Agri valley had previously been observed, our survey shows that the distribution of AP disease in Europe extends further south than previously thought and that the climatic conditions of southern Italy are not unsuitable for this quarantine disease.

Diffusa presenza di scopazzi del melo in impianti familiari in Val d’Agri, Basilicata

MARCONE, Carmine;
2013

Abstract

Over the last three years, visual symptom assessment and PCR amplification were used to survey the occurrence of apple proliferation (AP) disease in low-intensity orchards in Agri valley, a major cultivation area of Basilicata region. The apple trees examined, whose scion cultivars were not determined and consisted mostly of local cultivars, were more than 20 years old therefore had been exposed to insect vectors for a long time. The survey revealed that a high percentage of trees were infected reaching more than 50% in some locations. The symptoms of diseased trees were generally mild and consisted of enlarged stipules, rosettes, witches’-brooms as well as basal witches’-broom-like growth arising from large roots. However, incidence and severity of symptoms in the aerial parts of affected trees were pronounced only in trees which had been heavily pruned in the previous dormant season. Specificity of the primers used and restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA sequences employing SspI and BsaAI restriction endonucleases showed that the trees testing positive by PCR were infected by the AP agent ‘Candidatus Phytoplasma mali’. The high incidence of AP infections in low-intensity orchards in Agri valley is likely associated with inappropiate vector control. The trees examined were not or rarely treated with insecticides. On the other hand, typical AP symptoms seem to be uncommon in commercial apple orchards in Agri valley, which are treated with standard insecticide programs. Although a few AP-affected apple trees grown in a low-intensity orchard in Agri valley had previously been observed, our survey shows that the distribution of AP disease in Europe extends further south than previously thought and that the climatic conditions of southern Italy are not unsuitable for this quarantine disease.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/4011052
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