Prevalence and Survival of Xanthomonas axonopodis pv. phaseoli Causing Bacterial Blight in Common Bean (Phaseolus vulgaris L.)

Bacterial blight of common bean, caused by Xanthomonas axonopodis pv. phaseoli, poses a significant threat to bean cultivation in the mid-hill regions of Himachal Pradesh. This study was conducted in 2020-2021, to assess the prevalence and severity of the disease in major bean growing localities of Solan and Sirmaur districts and to determine the survival potential of the pathogen in infected plant debris and seed under varying conditions. Survey data revealed that the disease severity was higher in the rainy season (June-sown crop), ranging from 24.2% to 58.2%, compared to the summer season (March sown crop), where it ranged from 16.2% to 29.8%. The highest disease severity (58.2%) was recorded at Karganoo in Sirmaur district. Overall, Sirmaur district exhibited greater disease intensity than Solan. Survival studies demonstrated that X. axonopodis pv. phaseoli can persist up to 12 months in infected seed, although colony-forming units (CFU) declined significantly over time. In contrast, the pathogen survived for up to 10 months in plant debris placed on the soil surface but could not be recovered beyond 6 months when buried at depths of 10 cm and 15 cm.