Studies on Seed Borne Diseases of Cotton in Northern Karnataka
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Date
2013
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Publisher
UAS, Dharwad
Abstract
Thirty eight seed samples of cotton (Both Bt and Non-Bt) collected from different
private companies and research institute in northern Karnataka were subjected to initial seed
health testing by standard blotter method. The results of this investigation revealed the
predominance of Fusarium moniliforme, Alternaria alternata followed by species of
Curvularia and Aspergillus.
For detecting seed-borne bacterial infection, semi selective MSSXAN media and
XAN-D media was used. Investigation on standardization of seed health testing methods in
diagnosing seed-borne fungal infection in cotton, revealed the efficacy of standard blotter
method in diagnosing Alternaria and Curvularia, whereas 2,4-D blotter method was found to
be good for detecting Fusarium in cotton seed samples.
The pathogenic ability of seed borne fungi viz. A. alternata, Fusarium sp. and
Xanthomonas axonopodis pv malvacearum was proved in transmission studies.
Study on the location of seed borne fungi in the infected cotton seeds revealed that
Alternaria alternata, Aspergillus spp. and Curvularia sp. was noticed on the pericarp, where
as Fusarium sp was noticed in both pericarp and endosperm.
Among the six seed dressing fungicides tested against seed borne fungal infections by
rolled towel method, carboxin + thiram @ 0.2% was found most effective. Out of the eight
plant extracts tested, Azadirachta indica was found to be most effective @ 10%. Among the
four bioagents tested, Pseudomonas fluorescens showed least seed infection @ 0.8%. Among
the four priming agents tested, Pseudomonas fluorescens + jelly was found to be most
effective.
Under field experiments, Seed treatment with acid delinted + imidacloprid +
(carboxin + thiram) @ 0.2% along with foliar spray with hexaconazole @ 0.1% at 40 DAS
was found to be most effective against Alternaria blight and for bacterial blight, seed
treatment with streptocycline (500 ppm) + Imidacloprid was found to be good followed by
carboxin + thiram @ 0.2%.