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Studies on Fungal Pathogens of Vanilla with Special Reference to Colletotrichum gloeosporioides (Penz.) Penz. and Sacc.

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Title Studies on Fungal Pathogens of Vanilla with Special Reference to Colletotrichum gloeosporioides (Penz.) Penz. and Sacc.
 
Creator S.Ashoka
 
Contributor Yashoda R.Hegde
 
Subject Plant Pathology
 
Description crop mainly grown in Karnataka, Kerala and Tamil Nadu. It is cultivated for its
beans containing vanillin. Vanilla crop is affected by many pathogens in Karnataka.
The pathogens were isolated from infected parts of vanilla colleted from four
districts of Karnataka. On the basis of morphological and cultural studies, the
pathogens were identified as Colletotrichum gloeosporioides (Penz) Penz. and Sacc.,
Fusarium oxysporum Schlecht, Rhizoctonia sp. and Sclerotium rolfsii Sacc. Incidence
of C. gloeosporioides and F. oxysporum was observed in all four districts viz.,
Shimoga, Uttar Kannada, Dharwad and Belgaum whereas Rhizoctonia sp. and S.
rolfsii incidence was observed in Shimoga and Uttara Kannada districts respectively.
Lower incidence of C. gloeosporioides and F. oxysporum and absence of S. rolfsii and
Rhizoctonia sp. was observed under shade net conditions. Partial and discontinuous
wilting was observed in few places of Sagar taluk of Shimoga district which was due
to mixed infection of C. gloeosporioides and F. oxysporum. In the host pathogen
interaction C. gloeosporioides caused rotting of stem upto 15 cm from soil level in 45
days, F. oxysporum caused rapid wilting, Rhizoctonia sp. caused shredding of stem
and S. rolfsii caused girdling of stem. Rotting of shoot tip was observed wherever F.
oxysporum was used with other pathogens.
The conidia of C. gloeosporioides were single celled, hyaline, straight,
cylindrical or oval, measuring 15 x 3.50 μm. Potato dextrose agar and Richards’ agar
supported maximum radial growth and Richards’ broth supported maximum dry
mycelial weight of C. gloeosporioides on 12th day of incubation. The temperature of
300C, 12 h light and 12 h darkness and pH 6.0 were found to be best for the fungal
growth.
Under in vitro conditions, neem leaf extract at 10 per cent concentration and
Trichoderma harzianum were able to reduce the growth of pathogen to a remarkable
extent. Systemic fungicides viz., triadimefon, benomyl, prochloraz and combiproduct,
Carbendazim 12% + Mancozeb 63% were effective in completely inhibiting the
growth of pathogen at all three concentrations (0.1, 0.05 and 0.025%). Non-systemic
fungicides viz., mancozeb and copper sulphate at 0.30 per cent were found effective
in inhibiting growth of pathogen to a remarkable extent.
 
Date 2016-10-24T18:32:54Z
2016-10-24T18:32:54Z
2005
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/81641
 
Format application/pdf
 
Publisher UAS, Dharwad