The focus 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 have moved forward to identify naturally occurring phages and to construct modified tailocins that are active against strain BT-1. Once �Candidatus Liberibacter asiaticus� (Las) is successfully cultured, the protocols developed for L. crescens can be translated to Las. We have demonstrated that the tail fibers of tailocins can be deleted and complemented. Since the R-type pyocin systems have been well studied, we have initiated studies using the R2 platform and designed fusions between N-terminal tail fiber region of the R2 and C-terminal portions of tail spike from BT-1 prophages. We have identified the BT-1 tail spike protein based on topology. We are continuing the search for naturally occurring phages active against L. crescens. Members of the Rhizobium, Agrobacterium and Liberibacter are in the family Rhizobiaceae. Because of their phylogenetic relationship, it is possible that members of the Rhizobiaceae could share receptors. Rhizobium spp., Agrobacterium spp. or L. crescens BT-1 were used as hosts for enrichments from environmental samples. Several new Agrobacterium and Rhizobium phages have been isolated and purified. Electron microscopy studies will confirm their morphology. It is our experience that growth conditions can affect the bacterial surface, and therefore in vitro testing for phage and tailocin sensitivity. The phages are currently being tested against BT-1 using several modifications of medium BM7.