Studies on leaf blight of chrysanthemum caused by Alternaria alternata (Fr) Keissler
KrishiKosh
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Title |
Studies on leaf blight of chrysanthemum caused by Alternaria alternata (Fr) Keissler
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Creator |
G.S.Arun Kumar
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Contributor |
B.C.Kamanna
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Subject |
Plant pathology
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Description |
Among the several diseases, Alternaria leaf blight is one of the most destructive foliar disease which causes heavy loss in chrysanthemum. Survey during kharif/rabi 2007 revealed that Alternaria leaf blight was severe in all the four districts viz., Dharwad, Haveri, Gadag and Koppal.. Isolation and morphological studies revealed Alternaria alternata (Fr.) Keissler as causal organism. The weather studies revealed that per cent disease index (PDI) was progressing at linear rate throughout the plant growth and it was negatively correlated with minimum temperature, relative humidity (morning and evening). While, positively correlated with maximum temperature and rainfall. The prediction model developed for PDI was linear i.e., Y = a + b, t, where a = 1.35 and b = -0.17; with high R2 value of 0.96. Out of nine different fungicides tested in vitro, Propiconazole and Hexaconazole at all the concentrations (0.1%, 0.2% and 0.3%) completely inhibited the mycelial growth of A. alternata. Among the six bio-control agents tested against A. alternata under laboratory condition in dual culture, Trichoderma harzianum recorded highest inhibition of radial growth. T. koningii, T. viridae, and T. virens were next in order. Bacterial antagonists proved to be least effective. Out of six plant extracts tested against A. alternata, NSKE followed by neem leaf extract and garlic clove extracts were highly inhibitory to A. alternata, while tulasi leaf extract proved to be least inhibitor. In case of field evaluation of fungicides, botanicals and bio-agent Hexaconazole (0.1%) effectively controlled the disease incidence which recorded very less per cent disease index. followed by Chlorothalonil (0.2%) and Mancozeb (0.2%). |
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Date |
2016-10-27T18:32:34Z
2016-10-27T18:32:34Z 2008 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/82614
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Format |
application/pdf
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Publisher |
UAS, Dharwad
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