Vismax®:A novel peptide-based therapeutic for mitigation of citrus diseases, including HLB

Vismax®:A novel peptide-based therapeutic for mitigation of citrus diseases, including HLB

Report Date: 12/19/2023
Project: 20-015   Year: 2023
Category: Other
Author: Michelle Leslie
Sponsor: Citrus Research and Development Foundation

1. Please state project objectives and what work was done this quarter to address them: Objective: Determine whether Vismax® treatment promotes resistance to other [than HLB] major citrusdiseases, specifically Phytophthora root rot and citrus canker. Demonstrate that Vismax® treatment of greenhouse-inoculated trees reduces disease severity and/or incidence. Work: Dr. Megan Dewdney (U. Florida IFAS CREC) and her team have performed Phytophthora root rot greenhouse cone-tainer and Rhizotron trials, in order to evaluate rates of drench-applied Vismax® in combination with and comparison to Foliar-applied Vismax® for their ability to promote resistance to phytophthora root rot in susceptible orange seedlings by comparing dry structural and fibrous root masses, scoring roots and foliage for visible evidence of Phytophthora infection, and measuring Phytophthora incidence at root tips. Plant measurements and scoring of disease symptoms is complete for the Spring 2023 and Fall 2023 Phytophthora cone-tainer trials, and preliminary analysis indicates that both soil drench and foliar applications of Vismax® improve root health. Also with Dr. Dewdney, a series of citrus canker trials were intiatied to further explore the effects of Vismax® application timing, rate, and method (root drench vs. foliar) on canker disease progression in a susceptible orange vareity. Data has been collected and is currently being analyzed.  This past quarter, Vismax® received full US EPA section 3 registration as a biochemical pesticide with a new active ingredient, Flg22-Bt Peptide. A supplemental distribution label was subsequently granted in the state of Florida to Nutrien Ag Solutions under the product name, Aura Citrus, for applications targeting citrus greening/HLB and citrus canker. 2. Please state what work is anticipated for next quarter: Two successful Phytopthora cone-tainer trials were completed in 2023. In Q1 2024, statistical analyses will be conducted for the trials with both individual and combined data sets. The Rhizotron trial is a more detailed and labor-intensive trial that enables root observaton throughout the duration of the trial, giving more data about the timing and level of protection provided throughout disease progression. Data collection and statistical analyses of the Rhizotron trial will be completed in Q1 2024. For citrus canker trials, the number and severity of lesions are being analyzed. Together with field trials results, this data will inform grower recommendations for applying Vismax® as a preventative treatment for citrus canker in susceptible oranges. 3. Please state budget status (underspend or overspend, and why): The project is at budget, and is on track to be completed by the end of the NCE period (Feb 29, 2024).


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