Role of Antibiosis in Control of Cabbage Black Rot Caused by Xanthomonas campestris pv. campestris

Abstract

Two different antagonists, Bacillus subtilis, Pseudomonas fluorescens and Tango fungicide, were contemplated against cabbage black rot caused by Xanthomonas campestris pv. campestris (Xcc) in vitro and in vivo. P. fluorescens was the most efficient bioagent in repressing of the pathogenic bacterium took after Bacillus subtilis. The fungicide Tango was the most potent one in hindering the development of the causal bacterium in vitro more than other bioagents. Field experiments during 2014 and 2015 seasons have shown that spraying cabbage plants with the tested bioagents and the fungicide four times resulted in a significant decrease in severity caused by natural infection by the pathogen with a significant increase in yield component. The fungicide was potentially functional than the other bioagents. Tango was the most effective treatment for decreasing the severity of the disease and increasing the produced vegetative components. Meanwhile, the bioagent B. subtilis was the lowest in potential and other treatments recorded intermediate figures. Vitamin-C and total phenols content as well as the activity of peroxidase, polyphenoloxidase and chitinase in cabbage leaves infected by X. c. pv. campestris were greatly low levelled in infected leaves of compared with uninfected or the tested bioagents and fungicide resulted in a considerable increase in these contents compared with the infected leaves.