Biological control of foot rot of black pepper with antagonstic bacteria from rhizosphere
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Date
1998
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Department of Plant Pathology, College of Agriculture, Vellayani
Abstract
An attempt was made at the Department of Plant
Pathology, College of Agriculture, Vellayani to screen and
identify antagonistic soil bacteria with potentiality to suppress
Phytophthora capsici, the incitant of foot rot or quick wilt of
black pepper. Bacteria were isolated from the rhizosphere of
wild pepper plants, pepper plants in disease free plantations,
healthy plants in diseased pepper plantations, pepper plantations
where organic farming is practiced, undisturbed forest soils and
vermicompost. Population of bacteria in the various 50ils and
vermicompost showed great variability ranging from 13.67xl04 to
168xl04 cfu g-1. High population of bacteria was recorded from
the rhizosphere soils of healthy plants in diseased pepper
plantation of Pepper Research Station, Panniyur and wild pepper
plants in virgin forest of Punnamala region of Silent Valley.
Of the 194 isolates, only 15 isolates showed antagonism
to P. capsici in vitro. Three isolates B5, B7 and Bl3 were
highly effective in in vitro inhibition of sporangial production
by the pathogen and disease suppression in rooted cuttings of the
susceptible pepper variety, Karimunda. Isolate B13 was found to
be the most ideal candidate with the ability to reduce mortality
of pepper plants and foliar blighting and to provide continued
protection for a longer period. The isolate was effective as
cell free filtrates also and was found to produce
small
quantities of the enzyme, cellulase. Isolate B5 also reduced the
disease in pepper plants. The live cells and cell free filtrate
of this isolate afforded good foliar protection against
P. capsici. The isolate B7 was found to have a dual role
disease suppression and growth promotion. All these isolate~ had
good survival in the rhizosphere of pepper plants with population
of 104 to 105 cfu g-l soil. The effective isolates were gram
positive, aerobic,
sporulating, rods with ability to produce
catalase and were found to conform to genus Bacillus.
Description
PG
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Citation
171238