Four different rootstocks were cultured, namely Prunus mahaleb L., Gi-Sel Al (P. fruticosa Pall.X P. avium L.), Damil (P. dawyckensis Sealy) and Tabel (Edabriz). Plants were inspected for symptoms from mid-April through mid-May. Leaf samples from Prunus mahaleb and Gi-Sel Al were collected in the middle of May for ELISA and sap transmission tests. Damil and Tabel were not tested because they had already been certified. Meristems from both axillary and terminal buds were cultured in spring (May), summer (July-August) and autumn (September-October).