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Studies on etiology, epidemiology and management of wilt complex of coleus forskolhiI (WILD.)Briq.

KrishiKosh

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Title Studies on etiology, epidemiology and management of wilt complex of coleus forskolhiI (WILD.)Briq.
 
Creator R.Ammajamma
 
Contributor Yashodha.R.Hegde
 
Subject Plant Pathology
 
Description Coleus forskohlii is an important medicinal crop subjected to attack by several
diseases among which wilt complex is becoming severe in recent years. Survey on disease
incidence in different districts of Karnataka revealed 19 to 41.67 per cent incidence.
Pathogenicity tests confirmed Rhizoctonia bataticola, Fusarium chlamydosporum, Sclerotium
rolfsii and Ralstonia solanacearum were pathogenic.
PDA, Richard’s broth, sucrose and potassium nitrate supported the maximum
mycelial growth of three fungal pathogens. Growth period; 12, 16 and 10 days of incubation,
pH; 6.5, 7.0 and 4.0, were required for maximum growth of Rhizoctonia bataticola, Fusarium
chlamydosporum and Sclerotium rolfsii respectively. Fifteen isolates of Rhizoctonia
bataticola were collected and categorized based on colony colour and texture. PCR - based
RAPD analysis revealed cent per cent polymorphism in OPA02, OPB02, OPB04, OPF03,
OPF07 and OPF10. Dendrogram indicated three major clusters.
There was increase in total phenol and decrease of sugar contents due to infection.
Inoculum of 12, 10 and 8 per cent was required to get 100 per cent disease in Rhizoctonia
bataticola, Fusarium chlamydosporum and Sclerotium rolfsii respectively. Pathogens
survived saprophytically on host debris. Soil temperature of 300C and 30 per cent soil
moisture was required for maximum growth of S. rolfsii. Combined infection resulted in
rapid wilting of the plants. However, in sequential inoculation, Ralstonia followed by
Rhizoctonia bataticola caused more disease.
Trichoderma harzianum showed stronger antagonistic activities against Rhizoctonia
bataticola and Sclerotium rolfsii; Trichoderma koningii against Fusarium chlamydosporum.
Eupatorium and ocimum leaf extracts at 10 per cent were effective against Rhizoctonia
bataticola and Fusarium chlamydosporum respectively. In field, soil application of
FYM@10t/ha+ Trichoderm harzianum@25 kg/ha helps to manage disease effectively and to
increase the yield. Equally effective is the soil drenching of carboxin+thiram @0.1% for
obtaining maximum yield with minimum disease.
 
Date 2016-07-23T12:01:15Z
2016-07-23T12:01:15Z
2010
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/69528
 
Format application/pdf
 
Publisher UAS Dharwad