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STUDY ON THE FUNGAL LEAF BLIGHT DISEASES OF Gerbera jamesonii

KrishiKosh

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Title STUDY ON THE FUNGAL LEAF BLIGHT DISEASES OF Gerbera jamesonii
 
Creator Phukan, Tanushree
 
Contributor Nayak, N
 
Subject ornamental crops, Alternaria leaf spot disease , conidia
 
Description Floriculture has become one of the most important commercial trade of agriculture
in our country. India has the maximum area under ornamental crops (88,600 ha)where
gerbera ranks 5
th
among the most favoured flowers. A good number of fungal pathogens
attack the gerbera plants incurring substantial loss in the yield of flowers. Alternaria leaf
spot disease has been observed on all the varieties of gerbera wherever it is grown.
Therefore , in depth studies were undertaken pertaining to Alternaria leaf blight of gerbera
with its generation of following information.

The incidence of leaf spot caused by Alternaria alternata ranged from 15-45% as
studied under protected cultivation in and around Bhubaneswar. The symptomatological
results revealed oval, circular or irregular brown to black lesions with concentrated rings on
leaves. The pathogenicity of the fungus Alternaria alternata on potted gerbera plants was
done and isolated fungus from the infected gerbera plant was found identical to the earlier
one.
The pathogen produced conidia in Potato Dextrose Agar medium which measured
an average of 24.41 x 5.16µm. Host leaf extract medium supported highest growth(7.16 cm)
of the fungus followed by Richard’s agar(7.06 cm),Waksman agar(7.00 cm), Oat meal
agar(6.16cm), Czapek’s agar(5.06 cm), Potato Dextrose Agar(4.63 cm) and Water Agar
media(1.12 cm).A pH of 7.0 showed best mycelial growth(2.27 cm) as compared to pH
4.0(0.72 cm), pH 5.0(1.79 cm),pH 6.0(2.10 cm),pH 8.0(2.17 cm) and pH 9.0(1.85 cm).

The rhizome extract of Zingiber officinale exhibited a higher degree of growth
inhibition(64.85%) followed by extracts of Allium sativum clove(63.25%), bulb extract of
Allium cepa(59.04%), leaf extracts of Azadirachta indica(57.17%), Aegle marmelos
(57.19%)and Ocimum sanctum(55.82%). Evaluation of fungal bio agents against Alternaria
alternata revealed that Trichoderma harzianum proved superior (51.61%) followed by
Trichoderma viride(48.38%) and Metarrhizium anisopliae(38.70%). In vitro evaluation of
fungicides against Alternaria alternata showed that Hexaconazole 4%+ Zineb 68% WP
was superior in inhibiting (67.30%) as compared to Copper oxychloride 40%WP(66.20%),
Carbendazim 12% + Mancozeb 63% WP(60.37%), Mancozeb 75 WP(54.48%),
Carbendazim 50%WP(45.43%) and Thiophanate methyl 70WP(44.67%).
 
Date 2017-01-20T10:59:32Z
2017-01-20T10:59:32Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/97268
 
Language en
 
Relation Th;4563
 
Format application/pdf