DELAY OF ONSET OF LEAFROLL SYMPTOM EXPRESSION IN Vitis vinifera ’LIEMBERGER’ FROM RIBAVIRIN-TREATED IN VITRO CULTURES

Ribavirin added at a concentration of 10 mg/L or more to in vitro cultures of Vitis vinifera ’Liemberger’ infected with grapevine leafroll delayed the onset of symptom expression by an average of 50 days. At the concentrations tested, the effect was independent of drug concentration and a 30-day treatment was as effective as a 90-day treatment.Key words: Ribavirin, tissue culture, grapevine leafroll