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2012 - 20162
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Subject: Plant Pathology × Author: Hulagappa × Start date: 2010 ×
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    ThesisItemOpen Access
    Epidemiology, Molecular Characterization for Resistance to Turcicum Leaf Blight and Integrated Management of Major Foliar Diseases in Maize
    (University of Agricultural Science, Dharwad, 2016-08) Hulagappa; Nargund, V.B.
    Survey was conducted during two kharif and rabi seasons (2014-15 and 2015-16) in northern Karnataka for recording foliar diseases severity. Among the foliar fungal diseases of maize turcicum leaf blight (TLB) caused by Exserohilum turcicum is major yield limiting factor. Survey study revealed that maximum disease severity (96.00 PDI) of TLB was noticed in Gurlapur village of Belagavi district. Kalburgi district remained free from all foliar diseases even at the cob formation stage. The maximum severity of TLB was recorded in 2014 kharif compared to 2015. Thirty isolates collected during survey showed morphological variation on PDA. The full length ITS rDNA region of E. turcicum was amplified with ITS-1 and ITS-4 primers. Genetic variation among isolates of E. turcicum was studied by analysis of the ITS-RFLP profile after the digestion with restriction enzymes (Taq I, and Hind II) which showed specific polymorphism. Field experiments were undertaken during two kharif seasons at MARS, Dharwad (2014 and 2015). Among 23 inbred lines screened under artificial epiphytotic condition, three lines (PDM-74-1, 4641 and 260) exhibited moderate resistant reaction.The application of different SSR markers successfully provided the information on similarity and/or diversity as well as the heterozygosity of the allelic loci for all the 23 inbred lines. Epidemiological study revealed a positive correlation with cumulative rainfall and temperature. The multiple linear regression equation was developed and the coefficient of determinative value (R2) was more than 0.90 in two consecutive kharif seasons. In the fungicidal management of TLB, spraying of propiconazole @ 0.1 per cent at 35, 50 and 65 days after sowing recorded least PDI (12.44) with maximum grain and fodder yield (73.01 q/ha and 10.33 t/ha). In the four integrated disease management modules, highest grain and fodder yield were recorded in chemical module (72.40 q/ha and 9.01 t/ha) with 2.58 B:C ratio.
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    ThesisItemOpen Access
    Studies on Maydis Leaf Blight of Maize Caused By Drechslera maydis (Nisikado) Subram. And Jain
    (UAS, Dharwad, 2012) Hulagappa; S.I. Harlapur
    The investigation on maydis leaf blight (MLB) of maize caused by Drechslera maydis (Nisikado) Subram and Jain, comprised of disease survey, pathogen variability studies, evaluation of fungicides, bioagents, phytoextracts and field management of the disease were conducted during kharif and rabi 2011 at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad. The results of the investigation are summarized hereunder. During kharif 2011, maximum disease severity was recorded in Ranebennur (56.26%). Least severity was noticed in Kushtagi (33.88%). During rabi 2011, maximum disease severity was observed in Ranebennur (50.26%). Least severity was noticed in Kushtagi (27.88%). During the survey programme, the maydis leaf blight infected leaf samples were collected and pure hyphal tip cultures of twelve isolates were maintained on potato dextrose agar. Studies on morphological and cultural variability indicated that, isolate Dm1 was found to be fast growing, excellent sporulation with deep black pigmentation. Random Amplified Polymorphic DNA studies distinguished the twelve isolates into major cluster, A and B. Majority of the isolates were in cluster A under various sub-clusters, showing some degree of variability. Cluster B has 6 isolates in case of sub cluster A1, it has got a single isolate Dm5, which was showing diversification from other isolates. Propiconazole 25% EC @ 0.1% found to be effective under in vitro studies which recorded maximum mycelial inhibition at all the concentrations tested followed by Hexaconazole 4% WP + Zineb 68% WP. Among the botanical, neem leaf extract and bioagent, Trichoderma virens recorded maximum mycelia inhibition. Field studies indicated that two sprays of Propiconazole 25% EC @ 0.1% at 35 and 50 days after sowing found to be highly effective (20.68% PDI, 73.46 q/ha grain yield and 10.96 t/ha fodder yield) in the management of the disease.