Copper bactericides have been used since decades for the control of bacterial plant pathogens. Repeated use of copper bactericides against bacterial spot (BLS) xanthomonads has led to spread of the copper resistance trait in the pathogen population. Transfer of copper resistance genes via large conjugative plasmid has been a well characterized mechanism in spread of copper resistance in BLS pathogens. We recently identified copper-tolerant Xanthomonas perforans strains that contained chromosomally-encoded copper resistance genes on a genomic island. Interestingly, the structure of this island differs from the previously reported chromosomal island of X. vesicatoria strain XVP26. In this study, we investigated the transfer potential of chromosomally-encoded copper resistance genes from copper-tolerant X. perforans strains to the copper sensitive X. perforans strains under in vitro and in planta conditions. Co-infiltration of copper-tolerant and copper-sensitive strains into tomato leaves failed to obtain copper-tolerant transconjugants in the sensitive background. However, dip-inoculation of the mixture of copper-tolerant and copper-sensitive strains allowed us to obtain copper-tolerant transconjugants of sensitive strains. This observation indicates that transfer of chromosomally-encoded copper resistance genes was successful during epiphytic colonization of pathogen.