Resistance of almond cultivars to Plum pox virus (sharka)

Sharka, a disease caused by Plum pox virus (PPV), mainly affects some Prunus species, including apricot, peach and plum, and to a lesser degree, sweet cherry and sour cherry. In almond, different PPV isolates have been transmitted experimentally to the ‘Aï’ cultivar. In this study, the resistance of 10 almond cultivars to a Dideron PPV isolate was evaluated in controlled conditions by grafting the cultivars on to inoculated GF305 peach rootstocks. The results demonstrated a high level of resistance to PPV in all the almond cultivars assayed. They did not show any symptoms and were ELISA and RT‐PCR negative, despite the strong symptoms observed in their GF305 rootstocks. The implications of these results for the dispersion of PPV, and the potential role of almond as a source of resistance to PPV in other Prunus species such as peach, are also discussed.