The most widely used tests use primers and probes based on the 16S ribosomal RNA (rRNA) gene. The 16S rRNA-based tests to detect the three species are species-specific and must be performed sequentially. In this article a qPCR diagnostic test useful for the detection of all species of Liberibacter infecting citrus is described. In addition, the degenerate genus-specific primers and probe successfully detected ‘Ca. Liberibacter solanacearum’, a psyllid-transmitted pathogen associated with disease in tomato, carrot, and potato.