ARI REVIEW FOR 2016-2017

isolates/strains. The molecular techniques used in the present work enabled, in addition to the differentiation of mild and severe isolates, the establishment of relationships of Cypriot isolates to universal isolates, including the severe isolates T36 and T3 from Florida, B246 from South Africa, B-CTV from India and the mild isolate 28C from Portugal. These results substantiate our belief that CTV was introduced in Cyprus with imported budwood from South Africa in the 1930´s when there was not much knowledge about viruses and more recently from other countries, as travelling became easier during the last three decades. ( L.C. Papayiannis and T. Kapari ) In vitro techniques for elimination of citrus pathogens from infected citrus plants using micrografting, chemotherapy and coldtherapy In vitro micrografting, chemotherapy and coldtherapy techniques have been using for sanitation of citrus species and varieties infected by Citrus tristeza virus (CTV) and/or citrus viroids. Several citrus tree varieties including the lemon varieties Adamopoulou, Verna, Polyphori and Lapithou, the orange varieties Navelina, Washington navel, Jaffa, Siekeriko and Aematousiki, the mandarin varieties Clasuelina, Page and Arakapas, Frappa and Bergamot were selected. Four Mexican lime (ML) trees infected by severe or mild CTV isolates from Cyprus were used. All trees were tested for viruses and viroids by biological indexing, by ELISA for CTV and CPsV, and by RT- PCR for viroids. They were all found free of CPsV, CVV, concave gum and impietratura. Thirteen trees were infected by CEVd and/or other viroids and one was infected by both CTV and viroids. The micrografting technique in vitro was used for elimination of viroids and CTV in the selected citrus isolates. Chemotherapy in vitro was tested in ML trees infected by CTV. Coldtherapy in vitro was tested in Lapithou lemon tree infected by CEVd and HSVd. Micrografted plants were re-grafted on sour orange seedlings in vivo , or were potted and those which were successfully established were transferred to the glasshouse. They were tested 6-9 months later for CTV and viroids present in meristem donor mother plants. One or more plants produced by micrografting from all mother plants were found free of CTV and/or viroids. Elimination of CTV on apical meristems was achieved by chemotherapy in vitro using 30, 40 and 50 mg/l ribavirin or 30, 40 and 50 mg/l methotrexate. Elimination of viroids by coldtherapy at 10 °C for 5 weeks was not possible, but was successful by coldtherapy at 4 °C for 5 weeks. ( T. Kapari-Isaia and L.C. Papayiannis ) 42 Plant Protection