P-042 - RejuAgro A: A Sustainable and Effective Antimicrobial for Managing Citrus Canker and Huanglongbing

The citrus industry faces severe challenges from citrus canker and Huanglongbing (HLB), leading to significant yield losses, particularly in Florida. The 2024 EPA ban on streptomycin (STR), a key antibiotic used in disease management, has heightened the urgency for effective and sustainable alternatives. This study evaluates RejuAgro A (RAA), a novel antimicrobial derived from Pseudomonas soli 0617-T307, for citrus disease control. Multi-year, multi-site field trials demonstrated that foliar applications of RAA at 20–30 µg/ml significantly suppressed Xanthomonas citri subsp. citri, the pathogen responsible for citrus canker, achieving efficacy comparable to STR at 1200 µg/ml. Additionally, greenhouse trials showed that RAA at 20 µg/ml markedly reduced Candidatus Liberibacter asiaticus (CLas), the causal agent of HLB, while promoting new growth in infected trees. Field trials confirmed that RAA, when applied as a foliar spray at 20–30 µg/ml, effectively mitigated HLB severity to levels similar to STR. Greenhouse and field assays of trunk-injected RAA demonstrated promising disease suppression, with efficacy comparable to oxytetracycline. The high efficacy of RAA at lower concentrations results from multiple mechanisms, including direct antibacterial activity and plant defense induction. RAA’s physicochemical properties such as pKa 7.76 and a low log K_ow contribute to its superior translocation and retention on plant surfaces compared to STR. These findings position RAA as a promising solution for citrus disease management, supporting long-term industry sustainability.