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STUDIES ON CERCOSPORA LEAF SPOT OF OKRA (Abelmoschus esculentus L.)

KrishiKosh

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Title STUDIES ON CERCOSPORA LEAF SPOT OF OKRA (Abelmoschus esculentus L.)
 
Creator SURAJ, P
 
Contributor SUBBA REDDY, C
 
Subject STUDIES, CERCOSPORA, LEAF, SPOT, OKRA
 
Description The fungus causing leaf spot of okra was isolated and
identified as Cercospora abelmoschi (Eill. and Ev.) relative
efficacy of different methods of inoculation was worked out. Host
range studies, suitability of media, effect of pH, temperature and
light regimes during incubation on growth and sporulation of the
fungus were studied. Effect of weather parameters on disease
development and efficacy of various fungicides for the
management of the pathogen in the field were investigated.
Among the four inoculation methods employed,
atomization of spores and mycelial suspension technique was
found to be the most effective one.
The disease started as minute light olivaceous speck,
which enlarged to form angular sooty spots bounded by the vein.
The margins of the leaf spots were neither clearly marked nor
surrounded by any halo. Defoliation and stunted growth of the
plant resulted in poor yield due to severe infection.
Among the eight plants selected for the host range
studies only the natural host developed symptoms.
Potato dextrose agar was the most suitable medium for
the mycelial growth of fungi whereas, carrot leaf extract agar
found to be most suited for sporulation of the fungus. Maximum
growth of the fungus in terms of mycelial dry weight was recorded
at pH 5.0. The optimum temperature for mycelial growth and
sporulation in culture were 25°C and 30°C respectively.
Inoculation of the fungus under light for 6 h followed by 6 h
incubation in darkness resulted in sporulation.
All the weather parameters studied influenced the
incidence of leaf spot disease. The disease incidence increased
consistently with increase in relative humidity, maximum
temperature and sunshine hours. The incidence had negative
correlation with the minimum temperature and rainfall.
Studies on the field evaluation of the fungicides against
pathogen showed that, copper oxychloride (0.3%) was the most
effective fungicide showing minimum per cent disease severity
followed by carbendazim (0.1%), propiconazole (0.2%), propineb
(0.1%) and hexconazole (0.2%). mancozeb (0.25%) and
thiophanate methyl (0.2%) were relatively less effective.
 
Date 2016-08-20T09:54:01Z
2016-08-20T09:54:01Z
2004
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/73101
 
Language en
 
Relation D7620;
 
Format application/pdf
 
Publisher ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD