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INVESTIGATIONS INTO BLACK SHANK (PHYTOPHTHORA PARASITICA VAR.NICOTIANAE)-ROOT-KNOT (MELOIDOGYNE JAVANICA) COMPLEX IN TOBACCO

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Title INVESTIGATIONS INTO BLACK SHANK (PHYTOPHTHORA PARASITICA VAR.NICOTIANAE)-ROOT-KNOT (MELOIDOGYNE JAVANICA) COMPLEX IN TOBACCO
 
Creator KRISHNA KUMARI, A
 
Contributor SITARAMAIAH, K
 
Subject INVESTIGATIONS, BLACK SHANK, ROOT, KNOT, COMPLEX, OBACCO
 
Description Field survey of major tobacco growing areas of Guntur
and Prakasam districts of Andhra Pradesh revealed that the
black shank disease incidence was maximum during December
month of crop growth. An attempt was made to correlate the
black shank disease index with the root-knot severity index,
soil characters tics such as soil pH and electrical
conductivity, from four tobacco growing areas, at four
monthly intervals of observations. There was variation in
results with regard to black shank disease incidence in the
two districts surveyed. The black shank disease incidence
was correlated with root-knot severity in the month of
December only. '·As the root-knot severity increased the black
shank disease incidence also increased.
Pathogenicity tests conducted with two methods of
inoculation viz., spraying of fungal suspension on leaves of
tobacco plants., root-zone inoculation by pouring the fungal
suspension through plastic tubes inserted in the root .. zone
revealed that the disease development was rapid in the root ·
zone inoculation method.
Interaction studies
(Meloidogyne javanica) and
with the root-knot nematode
Phytophthora parasitica var.
nicotianae
different
at different inoculation intervals and
nematode inoculum levels indicated maximum
at
black
shank disease
fungus was
inoculation.
index (77-77%) in the treatment where the
inoculated three weeks after the nematode
Tobacco plants inoculated with the fungus after
nematode inoculation and simultaneous inoculation recorded
high black shank disease index than the plants inoculated
with the fungus before nematode inoculation and fungus alone
inoculation treatments. The plants in these treatments also
recorded decreased shoot and root length, fresh and dry shoot
and root weights than the plants inoculated with fungus
alone. The results also revealed that root-knot nematode
M.javanica pre-disposed tobacco plants to the entry and
establishment of the black shank fungus in roots. The effect
of nematode inoculum level also showed a consistent · decrease
in growth bf tobacco plants with an increase in inoculum
level.
Nematicides {carbofuran and phorate) tested as pre
inoculation treatment decreased the root-knot severity and
also decreased the black shank disease incidence at higher
doses {@ 6 and 8 kg a.i/ha) of application, than in the post
inoculation treatment when compared to the untreated control.
 
Date 2016-08-18T11:34:41Z
2016-08-18T11:34:41Z
1989
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/72890
 
Language en
 
Relation D3399;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD.