Novel multi-metal systemic bactericide for HLB control

Novel multi-metal systemic bactericide for HLB control

Report Date: 06/18/2021
Project: 18-020   Year: 2021
Category: Other
Author: Swadeshmukul Santra
Sponsor: Citrus Research and Development Foundation

The effect of five multi-metal bactericides containing Cu as minor component, Cu-Mg (MM25C75M), Cu-Zn (MM25C75Z), Cu-ZnO (MM20C80Z), Cu-ZnS (MM17C83Z), Cu-Mg-Zn (MM17C17Mg66Zn) and four respective controls without Cu (i.e. coated Mg, Zn, ZnO, ZnS) was evaluated on seedlings to determine metallic uptake, movement and potential change in plant tissues. The rate of foliar application was 1600ppm for Zn and Mg and 400 ppm for Cu. Metal content in seedlings were determined 14hrs after treatment. Residues on the leaves were imaged using scanning electron microscopy. Seedlings were thoroughly washed following a UF-IFAS recommended published protocol and elemental analysis of tissue samples (leaf, root and stem) was performed. Preliminary results showed that Zn and Cu moved systemically to the root system 14 hrs post foliar application. It appears that the treatment moved through phloem vascular system. We have noticed that there is a difference in uptake and mobility of ZnO and ZnS particles within the plant vascular system. Further investigation is needed to understand the rate of uptake and metal movement. We could not reliably differentiate the movement of Mg due to the presence of large amount of Mg in untreated controls (background). Analysis of the infrared spectroscopic signature of the tissues suggested a slight change in composition for some of the formulations, but further investigation is needed to confirm. To determine the application frequency, we have initiated time-based studies. However, we experienced delay in data collection due to seedling unavailability from the CREC greenhouse facility. Additional characterization of all the above industry-grade formulations are being carried out including DLS, Zeta potential, infrared spectroscopy and nanoscale imaging. We have identified certain characterization limitations with the agri-grade material using these tools. We will report our finding in the next reporting period. Our industry collaborator on this project has provided a batch of agriculture-grade NEW Cu product containing 2% Cu for potential registration, which is being investigated within the scope of this project.          


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