Browsing by Author "Praveena Deepthi, K"
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ThesisItem Open Access STUDIES ON THE MANAGEMENT OF LEAF BLIGHT OF GRAPE CAUSED BY Alternaria vitis (Cav.) Sacc.(ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD, 2006) Praveena Deepthi, KStudies were carried out to derive a suitable management strategy for Alternaria leaf blight of grapevine caused by Alternaria vitis (cav.) sacc. which is becoming serious in Andhra Pradesh. The cold sterilised extracts of different fermented materials (Neem seed kernels, Vermicompost, Sugarcane press mud, FYM + Paddy straw, FYM + Fish meal + Cellulose and Grape berries), fungicides, salicylic acid and biocontrol agents were tested against the mycelial growth and spore germination of pathogen. Grape berry fermented juice is superior over all other treatments in inhibiting the mycelial growth as well as spore germination of Alternaria vitis, at its higher concentration. 10 day fermented juice is more effective compared to 20 and 30 day fermented extracts. This is followed by neem seed kernel extract. Other water extracts of composts considerably inhibited the spore germination but not the mycelial growth. Among the fungicides tested Iprodione 25% + Carbendazim 25% (Quintal) at 0.1% and Indofil M-45(Mancozeb) at 0.25% completely (100%) inhibited the mycelial growth and spore germination of pathogen. Iprodione 25% + carbendazim 25% (Quintal) at 0.05% given 100% inhibition of mycelial growth. Salicylic acid is not consistent in its performance in inhibiting the mycelial growth. The maximum inhibition was 14.05% at its higher test concentration of 125 ppm. At the same concentrations it inhibited the spore germination upto 45.62%. The biocontrol agents Trichoderma viride and Pseudomonas fluorescens showed 66.67% and 55.6% of inhibitions respectively. The microflora, isolated from the grapevine phylloplane include ten fungal species like Trichoderma harzianum, T. viride, Aspergillus niger, A. tumarii, A. fumigatus, Paecilomyces variotii, Thielavia terricola, Cladosporium cladosporoides, Oidiodendron sp., Alternaria sp. and five bacterial isolates PPB-1Y , PPB-2R, PPB-3Ro, PPB-4W, PPB-5Cr. were observed. Among the fungi Trichoderma harzianum recorded highest mycelial growth inhibition of 72.8% and Pseudomonas fluorescens was the best among the bacteria with 65.91% growth inhibition and 5.34mm of inhibition zone. The treatments, which were proved effective in in vitro studies, were tested in the glass house on grapevine rooted cuttings of Thompson seedless variety for their efficacy against the Alternaria leaf blight. In all the methods of testing 10 day unsterilised grape berry fermented juice recorded minimum Percent Disease Index. Prophylactic application of 10 day unsterilised grape berry fermented juice at 25% and Iprodione25% + Carbendazim25% (Quintal) at 0.1% recorded minimum Percent Disease Index of 14.8% each followed by native Trichoderma harzianum, native Pseudomonas fluorescens with 17.29% each and Pseudomonas fluorescens (Bio control agent) with 22.23%. All the treatments were considerably effective in reducing the Percent Disease Index.