The focus of the project is to develop a bacteriophage (phage) and/or phage components (tailocins) system with activity against Liberibacter crescens strain BT-1 that will be a model for �Candidatus Liberibacter asiaticus�. Strain BT-1 harbors two prophages (LC1 and LC2) that we have determined are not inducible when the organism is exposed to UV or oxidative stress, which may indicate that the prophages are defective. Both of the phages are predicted to be podophages (i.e., no separate tail structure). Multiple constructs are being produced to determine the correct fusion that will produce a mature and active tailocin with activity against L. crescens. The assay system we have developed for L. crescens will be used for testing activity. Our goal is to construct tailocins with specific targeting to L. crescens by changing the C-terminal portion of the tail fiber. As a method to determine validity of the approach, we have constructed an unmarked and in-frame deletion mutant of the tail fibers of tailocin Bcep0425 and complemented in-trans with the homologous tail fiber and chaperone genes. We then constructed a series N-terminal tail fiber region derivatives (i.e. 153aa, 183aa and 243aa) of tailocin Bcep0425. When the N-terminal regions were joined with the heterologous C-terminal tail fiber regions of a known prophage we observed no activity against the new target. This is not surprising since the tail fiber structure is an elongated homo-trimers with a fibrous morphology and .-sheet topologies with unusual repetitive folds such as a triple .-helix, so it is necessary to identify the correct fusion. We will continue to make new constructs to identify the correct fusion. We are also continuing to search for naturally occurring phages of L. crescens. Rhizobium spp., Agrobacterium spp. and L. crescens BT-1 were used as hosts for enrichment with weed extracts, water and soil samples. No phages were detected for BT-1, however Rhizobium phages were isolated but showed no activity against L. crescens.