To those that do not study viruses, their names can be a problem. Most viruses can infect many species of plants but their names are based on the first host found infected by each virus and the type of damage caused. For example an important virus in dahlias is tomato spotted wilt virus. It was first found in tomato causing yellow spots and wilt symptoms. It does not cause the wilt in dahlias. Most viruses of dahlias come from agricultural crops. The exception is Dahlia mosaic virus (DMV) which is limited to dahlias. However, DMV is related to viruses of cauliflower, soybeans, peanut and other agricultural crops. We do not know the origin of DMV but viruses because of mutation, recombination and selection can adapt to new hosts.