The overall aim of this project is to develop and evaluate soft nanoparticles (SNP) to deliver natural biocides to the phloem of HLB infected trees by foliar and/or bark application. In the last quarter (July ‘ Oct ’14) the efficacies of formulations of all three EOs employed (EO-A, EO-B and Thyme oil) were evaluated through multiple methods. Subsequent to a careful selection of formulations based on efficacy against L. crescens, phytotoxicity and EPA registration of surfactants used, preparation of selected formulations have been scaled up. Currently, tests to assess efficacy of the formulations in HLB infected citruses via a bud graft technique at undergoing at Indian River Cirrus and Education Center, Ft. Pierce. Normally about six months are required for the assay to give results. To investigate the penetration of formulations into citrus leaves, dye doped microemulsion formulations have been prepared and applied by foliar application. From a number of oil soluble dyes, formulations were initially developed with fluorescein and Nile Red dyes. However, upon application to plants and successive dilution in the leaf, significant background interference was observed in the form of auto-fluorescence of chlorophyll and other leaf components (red region). Presently, new dyes have been selected between blue and green fluorescence. Formulations have now been developed with the new dyes like Bodipy 505/515, Vybrant DiO etc. which show fluorescence in 475-525 and 550-650 nm range. Leaf penetration experiments will begin in the upcoming weeks. In another approach we are aiming to developing methods for detection of EO transport to the phloem. Duncan grapefruit and Valencia orange plants have been acquired in order to do so. As an additional impact, zebra chip disease on tomato and potato caused by Ca. Liberibacter solanacearum (CLso) a close relative of CLas was identified as a rapid disease surrogate. The assays were all done at Texas A&M University. Some SNP formulations were successful in relieving zebra chip symptoms on tomato plants in a period of 30 days. QPCR tests are currently being conducted to get a quantitative evaluation.