We have now completed the field portions of the studies proposed, as well as of a follow-up study to confirm the results of both of the first studies. The field study of delivery of oxytetracycline (OTC) has now been published in the journal Antibiotics (Killiny et al., 2020). Overall the results conclude that:
1. OTC moved systemically, though a significant portion was trapped in the leaves into which it originally came in contact.
2. Most foliarly applied OTC was lost. This was determined by comparison with injection.
3. No adjuvant delivered greater quantities of OTC than water with no adjuvant.
4. Only injection reduced polulation of HLB-causing Candidatus Liberibacter asiaticus (CLas).
COVID-19-related delays in supplies have delayed quantification of streptomycin, though we now have assurances that the supplies will be delivered before the start of 2021. In the meantime, OTC quantification from the follow-up study, and CLas quantification are progressing for the follow-up study and the streptomycin-specific study. We anticipate publication of results within the 4 remaining months of the project.
Killiny, N., Hijaz, F., Gonzalez-Blanco, P., Jones, S. E., Pierre, M. O., & Vincent, C. I. (2020). Effect of Adjuvants on Oxytetracycline Uptake upon Foliar Application in Citrus. Antibiotics, 9(10), 677.