Abstract
Isolates of Xanthomonas campestris (Pammel) Dawson pv. sesami (Xcs) were collected from various locations in Pakistan
and were characterized using several biochemical tests including; (KOH) string test, gram staining, H2S production, catalase
activity, oxidation/fermentation of glucose, oxidase activity and nitrate reduction. The isolates were positive in tests for KOH
string assay, H2S, catalase and showed negative reactions in gram staining, oxidase test and nitrate reduction while oxidative
utilization of glucose was observed. To develop biological control for the pathogen we isolated numerous bacteria from the
rhizosphere of sesame plants and screened them for antagonism against the pathogen using the zone inhibition method. Out
of 87 isolates, 9 isolates were inhibitory to the pathogen in vitro. Pseudomonas fluorescens ID-3 exhibited the highest zone of
inhibition i.e. 7.97mm. All antagonistic isolates were tested for disease control under greenhouse conditions. Four sesame
lines that were found to be moderately resistant in previous studies (i.e. 95001, 96007, 96019, and 20003) were selected for
evaluating biocontrol efficacy. The isolates were found to control the disease and reduced severity to 3% compared to
untreated plants. The isolate P. fluorescens ID-3 was considered to provide the best disease control with each cultivar.
Average biocontrol efficiency (BE) of ID-3 was 78.25% while the best BE was obtained in line 96019, i.e. 81%.
