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Studies on leaf blight of chrysanthemum caused by Alternaria alternata (Fr) Keissler

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Title Studies on leaf blight of chrysanthemum caused by Alternaria alternata (Fr) Keissler
 
Creator G.S.Arun Kumar
 
Contributor B.C.Kamanna
 
Subject Plant pathology
 
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%).
 
Date 2016-10-27T18:32:34Z
2016-10-27T18:32:34Z
2008
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/82614
 
Format application/pdf
 
Publisher UAS, Dharwad