1. Developing a culture medium for Liberibacter asiaticus through comparative multiomics analysis with its closest cultured relative, L. crescens: Determined the optimal pH for the growth of L. crescens in M15 defined medium is 5.92, whereas in BM-7 is 6.5. Liberibacter crescens grows well in a pH range of 5.8 to 6.2. This is close to the pH of citrus phloem which is between 5.0 and 5.74, (Killiny. 2017). The level of Ca. L. asiaticus in the citrus phloem might be associated with the pH. During the culture of L. crescens, the pH of the medium rises dramatically. We are concerned that this rise may be limiting growth. As a result, we are conducting experiments to learn the source of the pH rise so that it can be mitigated. Chemically defined medium paper accepted for publication in Frontiers in Microbiology (Cruz-Munoz et al. 2018). Using several media based on M15 for culturing for Ca. L. asiaticus. In addition, various insect cell media are being tried. A cell line of the Asian citrus psyllid has been developed to determine whether Ca. L. asiaticus can be co-cultured with the insect cells. 2. Monitoring of citrus groves for non-target antibiotic resistance prior to and after application of streptomycin and oxytetracycline. A high throughput approach for the rapid assessment of streptomycin resistance has been developed and is now being tested with soil samples for citrus groves. Samples have been collected from four sites for this purpose. Streptomycin resistant bacteria have been isolated from these groves to test the efficacy of this method. To date, about 12% of soil bacteria appear to be resistant to streptomycin. More work is needed to test the level of streptomycin resistant levels in the pathogen in groves where streptomycin is being used compared to sites where it is not being use. 3. Developing second-generation antimicrobial treatments for citrus greening disease. A new antimicrobial Presto-Blue assay was developed for L. crescens on M15 defined medium. This approach was shared with representatives from Bayer who are developing their own high throughput assay against L. crescens. The new defined medium will greatly reduced the cost these assays and they should be more reproducible than BM-7 medium. We have learned that the undefined ingredients of BM-7 medium are quite variable among the manufacturers. 4. Phosphate utilization as a strategy for HLB-disease management A greenhouse experiment is in progress to determine whether foliar phosphate fertilization can recude citrate levels in phloem. Citrate is a preferred nutrient for Liberibacter. Phosphate fertilization is expected to reduce those levels in phloem sharply, thereby starving the pathogen. The phosphate foliar treatments are provided three times per week in the citrus macrophylla seedlings. Cruz-Munoz, M., Petrone, J. R., Cohn, A. R., Munoz-Beristain, A., Killiny, N., Drew, J. C., & Triplett, E. W. (2018). Development of chemically defined media reveals citrate as preferred carbon source for Liberibacter growth. Frontiers in Microbiology, 9, 668. Killiny, N. (2017). Metabolite signature of the phloem sap of fourteen citrus varieties with different degrees of tolerance to Candidatus Liberibacter asiaticus. Physiol. Mol. Plant Pathol. 97, 20-29. doi: 10.1016/j.pmpp.2016.11.004