APPLICATION OF THERMO- AND CHEMOTHERAPY IN VITRO FOR ELIMINATING SOME VIRUSES INFECTING Prunus sp. FRUIT TREES

Thermotherapy and chemotherapy in vitro were applied to eliminate Apple chlorotic leaf spot virus (ACLSV) and Prunus necrotic ring spot virus (PNRSV) from myrobalan (Prunus cerasifera var. divaricata Borgh.), PNRSV from ‘Empress’ plum (Prunus domestica L.) and Prune dwarf virus (PDV) from ‘Early Rivers’ sweet cherry (Cerasus avium (L.) Moench.) plants. ELISA assays conducted one year after therapy indicated that thermotherapy in vitro was highly effective for PNRSV and ACLSV elimination but it was not an efficient method for obtaining PDV-free ‘Early Rivers’ sweet cherry. Virazole® (Ribavirin) at concentration 25-100 mg l was effective in eliminating ACLSV from myrobalan and PNRSV from ‘Empress’ plum shoots but this therapy was not successful in eliminating PNRSV from myrobalan and PDV from ‘Early Rivers’ sweet cherry shoots. Combination of thermotherapy with Virazole® treatment at concentration 50-100 mg l enabled to eliminate PDV from ‘Early Rivers’ sweet cherry shoots and PNRSV from majority of treated shoots of myrobalan and ‘Empress’ plum. The higher concentrations of Virazole® (50-100 mg l) were phytotoxic for treated shoots, especially in case of ‘Empress’ plum.