Identifying possible sources of genetic variability is significant in the case of Citrus dwarfing viroid (CDVd) which has been proposed as a dwarfing agent for highdensity citrus plantings.In order to mimic the natural conditions of the field, a natural CDVd isolate (CMC) was used as an inoculum source for long-term and short-term bioassays in different citrus host species including both rootstock and grafted citrus species.