Abstract:
Studies on 'Management of bacterial wilt of solanaceous vegetables using microbial
antagonists' was conducted at the College of Horticulture, Vellanikkara during 2000-
2002. The major objective was to find out effective microbial antagonists against bacterial
wilt ofbrinjal, chilli and tomato.
Estimation of population of R. solanacearum showed the maximum in Vellanikkara
than Ozhalapathy. The total rnicroflora was higher in Ozhalapathy than Vellanikkara and
resistant varieties of the three crops recorded better association of microflora than
susceptible ones.
In in vitro evaluation , rhizosphere organisms isolated from the low wilt incidence
area (Ozhalapathy) exhibited better antagonism against R. solanacearttm than those isolated
from Vellanikkara. Among them, fungi were more effective than bacterial and actinomycete
antagonists. The major fungal antagonists belonged to Trichoderma spp. and Aspergillus
spp. T. viride (Ozhalapathy), T. pseudokoningii (forest soil) and Aspergillus niger
(Eruthyampathy) were the most effective ones against R. solanacearum. Among the
bacterial antagonists, P. aeruginosa and B. subtilis (Vellanikkara) were promising one. All
commercial antagonists viz. T. viride, A. niger (Varanasi), A. niger (AN 27) T. harziamtm, B.
subtilis and P. fluorescens were also effective against R. solanaeearum. Of the culture
filtrates tested, T. virens and.E. subtilis (commercial) showed the maximum inhibition of the
pathogen. The antagonists which were found most effective in laboratory condition
performed well in pot culture studies also. Among the different methods of application of
antagonists adopted, either seed treatment + soil drenching or root dipping were effective in
reducing the wilt incidence and in delaying the wilt appearance. Use of antagonists in highly
susceptible varieties did not give a promising control of bacterial wilt under field condition.
In field trial, using a moderately resistant variety Mukthi, antagonists showed some effect in
controlling bacterial wilt indicating that, an integrated effect by combined use of host
resistance and microbial antagonists can provide a better control of bacterial wilt pathogen
in the field.
