INVESTIGATOR: Roper, C.; Borneman, JA.; Jassby, DA.; Rolshausen, PH.; Vidalakis, GE.; Maloney, KA, N.; Liu, HA.

PERFORMING INSTITUTION:
UNIVERSITY OF CALIFORNIA, RIVERSIDE
RIVERSIDE, CALIFORNIA 92521

DEPLOYMENT OF A SPECTRUM OF BACTERICIDES TO CURE AND PROPHYLACTICALLY TREAT CITRUS HUANGLONGBING

NON-TECHNICAL SUMMARY: Our research objectives are to design and identify bactericides that can cure/suppress or prophylactically treat Huanglongbing (HLB), and to target these bactericides to the phloem where the associated bacterium, Candidatus Liberibacter asiaticus (CLas), resides. We will develop two classes of bactericides, the first based on silver and sulfur nanoparticles, the second rooted in natural product discovery, mining anti-CLas compounds produced by microbes that inhabit HLB survivor trees in Florida. The difficulty with any anti-HLB formulation is optimizing its delivery to the phloem. In all cases, delivery of the bactericides to, and within, the phloem sieve tubes to kill CLas will be of paramount importance. Thus, we will perform detailed analyses of the phloem transit routes that a given bactericide takes when introduced through common application methods (trunk injection, foliar application or root applications). We will also continue to develop a promising, new petiole/branch delivery system for use in field trees. We will explore the chemistry of bactericides to optimize uptake by the sieve tubes. Because significant amounts of phloem plugging occurs in CLas-infected trees, we will evaluate bactericide transit pathways at the whole-plant level at varying stages of infection. This work on HLB-phloem transit routes will provide important information for us and for others in the HLB research community who are evaluating delivery of materials to the phloem. We will integrate this research with a robust extension and outreach program that will be coupled with an economic cost-benefit analysis structured around adoption of these treatments into commercial citriculture.