The overall objective of our project is to develop a detection system for bacteriophage (phage) and/or phage components (tailocins) using Liberibacter crescens strain BT-1. We have accomplished that goal and used it to screen potential phage, tailocins and microbial compounds for activity against the model bacterium L. crescens BT-1. Since Liberibacter is a member of the Rhizobiaceae we have recently taken the approach that phylogenetically related microorganisms can share common surface components, such as phage receptor sites. Analysis of major outer proteins of �Candidatus Liberibacter spp.�, that are known to be expressed in planta and in the vector, identified several proteins that could potentially act as adsorption sites for phage and/or tailocins. Bioinformatics and structural analyses indicated that there is ~40% identity and ~61% homology of OmpA and TolC outer membrane proteins between Rhizobium spp., Agrobacterium spp. and Liberibacter spp. Therefore, our strategies has been to search for naturally occurring phages active against Rhizobium spp. and/or Agrobacterium spp. that may also show activity against Liberibacter spp. We have isolated a bank of three Agrobacterium spp. and 15 Rhizobium spp. phages. The Agrobacterium phages exhibit differential activity among Agrobacterium spp. hosts, as do the 15 Rhizobium phages, which indicates a diversity of receptor sites. One particular Rhizobium phage, R2phi3LR, forms plaques on both Agrobacterium spp. and Rhizobium spp. hosts, which is indicative of common receptor(s). As expected, the efficiency of plating for phage R2phi3LR was reduced 1000X when Rhizobium propagated phage was titered on Agrobacterium and vice versa. All purified phages are being increased to conduct plant studies that will evaluate the potential activity of the phages against �Candidatus Liberibacter spp.�.