From September through December 2016, we carried out all the control runs, and then the test runs for a high-throughput screen of compounds in the Stanford Chemical Screening facility. As of the end of December, we had screened over 115,000 compounds. As previously described, we looked at three Liberibacter transcription regulators: RpoH, VisNR, and LdtR, each with a corresponding target promoter driving enhanced GFP. To run the test, the reporter strains are grown for one day in selective media, in 384-well plates. We used minimal media to avoid background fluorescence found with rich media. At day 1, the test compounds are delivered to each well by pinning. Sealed lidded plates are grown for 17-19 hours. Each plate includes induced strains with or without test compound, uninduced bacteria (no compounds) and simple growth media. We have now screened 9 libraries, as follows. Each library name is followed by the number of unique compounds in the collection (number in parentheses). Diversity collections main screening libraries: Specs (30,106 unique compounds) Chembridge (23,865) ChemDiv (49,946) Kinase-targeted collections: ChemRX (9,706) Known Bioactive Collections: Sigma LOPAC qHTS (1,269) NIH Clinical Collection (377, tested in duplicate) Microsource Spectrum: MS Spectrum qHTS (1502) Biomol collections: ICCB (296) FDA (175) The preliminary number of inhibitory compounds is over 3600, but this number is an overestimate for several reasons. First, over 100 are simply toxic to all strains (inhibitory to growth as indicated decrease of over 50% compared to control). Second, the first pass of the screen had a very liberal interpretation of “inhibition”, asking for 30% inhibition of activity. Third, until the compounds are re-tested, it is unwise to draw any conclusions. We are presently retesting all compounds. With these cautions in mind, it is interesting to see the kinds of compounds we have found that inhibit activity of the Liberibacter protein transcriptional regulators. In our first screen Some are highly expensive chemotherapy drugs, which would not be practical for use in an agricultural situation but might provide interesting structural clues about inhibition. At the other end, we discovered inhibitory effects of some natural plant products such as certain flavonoids. We will have more precise data in the near future.