Comparative Study of Biological Control Agents against Common Bacterial Blight Disease in Dry Beans

Özet

Bean (Phaseolus vulgaris) is widely grown crops with high nutritional and commercial value that are staples on several continents. However, common bacterial blight (CBB), which is caused by Xanthomonas axonopodis pv. phaseoli is one of the most critical seed-borne destructive diseases of beans, having a major adverse effect on dry bean production, resulting in yield and quality losses. This study was conducted to examine the efficacy of biological control agents and a copper-based treatment in managing CBB under in vitro and in planta controlled conditions. In this study, various bacterial treatments, including Bacillus subtilis (Bs), Pseudomonas fluorescens (Ps), and a mixed treatment (Bs+Pf), were tested and compared to copper hydroxide (Ch) and control treatments. Disease incidence, disease severity index, and plant growth parameters such as plant height, number of leaves, root length, and weight, were evaluated to determine the effectiveness of each treatment. According to the results, there was a significant difference among treatments (p<0,01), as Bs demonstrated efficient in vitro inhibition (34.00 mm) and achieved 71% disease control in the in planta study. In the in planta study, the mixed treatment of Bs+Pf was the most significant among all treatments, reducing CBB to 10.33 and controlling the disease by 83.94%. Additionally, it inhibited the pathogen in vitro with a zone of inhibition measuring 23.66 mm. In comparison, Pf and the Ch control achieved 58.00% and 65.80% disease control, respectively. The mixed treatment yielded the greatest plant height (71.33 cm), while Bs produced the highest number of leaves (69.00) and the longest root length (19.00 cm). These findings underscore that integrating beneficial bacterial strains, particularly the combination of Bs and