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.
Keywords: Bioagents, cabbage, chitinase polyphenoloxidase,
peroxidase, phenols, and Xanthomonas campestris pv.
campestris.
Cabbage (Brassica oleracea L.) is one of the important vegetable crops
cultivated word wide (Gopalakrishnan and Rashmi, 2013). In Egypt, its commercial
cultivation is governed by various factors among which diseases play an important
role. Cabbage is an excellent source of Vitamin-C (44%) and other mineral
nutrition’s, containing more than 20% of the daily value for each of these nutrients
per serving (Terefa, 2017). The crop is attacked by a variety of pathogens both in the
nursery and the field. Black rot, caused by the bacterium Xanthomonas campestris
pv. campestris (Pammel) Dowson (Alvarez, 2000), is one of common and the most
dangerous diseases of cabbage.
The bacteria cells are gram-negative, short rods with rounded ends, bacterial
(Xcc) colonies were round with entire margins, slightly raised, shiny, butyrous in
consistency and light yellow in color on nutrient dextrose agar medium (Pammel,
1895). Bhide (1948) found that on NDA media the bacterium formed round colonies |
