Botanical-Based Strategies for Controlling spp. in Cotton and Citrus: In Vitro and In Vivo Evaluation.

Citrus canker, caused by subsp. , and bacterial blight, caused by subsp. , results in substantial economic losses worldwide, and searching for new antibacterial agents is a critical challenge. In this study, regional isolates AE28 and RQ3 were obtained from characteristic lesions on and , respectively. Essential oils extracted by steam distillation from the fresh aerial parts of and exhibited complete (100%) inhibition of bacterial growth in vitro at a concentration of 1000 ppm, as determined by diffusion tests. To evaluate the potential of these essential oils for controlling -induced diseases, in vivo assays were conducted on lemon leaves and cotton cotyledons inoculated with the regional AE28 and RQ3 strains. Two treatment approaches were tested: preventive application (24 h before inoculation) and curative application (24 h after inoculation). Preventive and curative treatments with essential oil significantly reduced citrus canker severity, whereas essential oil did not show a significant reduction compared to the control. In contrast, regardless of the treatment's timing, both essential oils effectively reduced bacterial blight severity in cotton cotyledons by approximately 1.5-fold. Gas chromatography-mass spectrometry (GC-MS) analysis identified geraniol and citronellol as the major components of essential oil, while limonene and t-cadinol were predominant in . These findings highlight the promising potential of botanical products as bactericidal agents, warranting further research to optimize their application and efficacy.