ETIOLOGY, EPIDEMIOLOGY, MOLECULAR CHARACTERIZATION AND INTEGRATED DISEASE MANAGEMENT OF TIP OVER DISEASE OF BANANA CAUSED BY Pectobacterium carotovorum subsp. carotovorum (Jones 1901) Hauben et al., 1999
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Date
2018-03
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University of Horticultural Sciences , Bagalkot
Abstract
A survey carried out in major banana growing districts of Karnataka to know
the incidence of tip over disease of banana during 2015-16 revealed that the severity
of disease was fo und to be more in tissue culture raised plantlets. The incidence of tip
over disease ranged from 0.40 to 99.27 per cent in the field. Banana plantations of one
to six months age were found to be more susceptible for infection. The tip over/ tip rot
disease symptoms included initial yellowing, browning and rotting of the unopened
leaves that progressed upward in the pseudostem destroying leaf bases causing
rhizome rotting and later decay of the plant with disagreeable odour. The
pathogenicity of Pectobacterium carotovorum subsp. carotovorum (Jones 1901)
Hauben et al., 1999 as well as Klebsiella variicola was proved in banana and
pathogen characters were studied and it was confirmed that Pectobacterium
carotovorum subsp. carotovorum and Klebsiella sp. were the causal agents of tip over
disease of banana. The disease incidence decreased progressively with the increase in
the age of the crop. Maximum temperature and average humidity were positively
correlated with the disease development. Maximum growth of Pectobacterium
carotovorum subsp. carotovorum was noticed at temperature of 32ÂșC and a pH of 7.0
under in vitro conditions. The pathogen was found to survive in all the seventeen
tested host species. Molecular characterization of Pectobacterium carotovorum subsp.
carotovorum were done using 16S rRNA and complete sequencing of the ten isolates
of the pathogen was undertaken and the sequences were deposited in national gene
bank.
Under in vitro conditions PM-2A (bacterial bio-agent), kokum (botanical) and
bronopol were found to show inhibitory effect against Pectobacterium carotovorum
subsp. carotovorum. Compatability studies under in vitro conditions did not show any
inhibitory effect against the pathogen, hence under field conditions treatments were
drenched individually. Among the field experiments, Bronopol @ 500 ppm + Copper
hydroxide @ 2gm/lit exhibited maximum inhibitory effect when drenched
sequentially for 4 times at 15 days intervals, where as in the second plot experiment,
streptocycline @ 500ppm+ copper hydroxide @ 2000ppm has shown maximum
inhibitory effect with higher fruit yield and net returns. Red banana, Yelakki bale and
Hanuman genotypes exhibited resistant reaction to Pectobacterium carotovorum
subsp. carotovorum under artificial inoculation conditions where as Grand Naine bale
and Rajapuri bale genotypes recorded highly susceptible reaction.
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