Epidemiology and Management of Leaf Spot of Cotton Caused by Alternaria spp.
KrishiKosh
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Title |
Epidemiology and Management of Leaf Spot of Cotton Caused by Alternaria spp.
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Creator |
Govindappa N. Hosagoudar
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Contributor |
S.N. Chattannavar
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Subject |
Plant Pathology
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Description |
Cotton, does not need much emphasis as being the principal raw material for a flourishing textile industry. The research studies revealed that the maximum Alternaria leaf spot disease severity was recorded in Gulbarga, Yadagiri, Dharwad and Raichur districts. Among 17 isolates, in morphological studies mean colony diameter ranged between 60 mm (Hirebagevadi) to 84 mm (Bagalkot). The mycelial width was larger in Kalmala (4.76 μm) and was least in Hattigudoor (2.53 μm). The dimensions of conidia of Kalmala isolate showed maximum size of 43.98-76.89 x 8.43-18.70 μm and Annigeri isolate showed maximum beak length of 16.30 μm. The temperature studies revealed that, the Hanumanamatti isolate (230.20 mg) recorded maximum dry mycelial weight. The highest dry mycelial weight was recorded at 30oC (252.38 mg) followed by 25oC (237.76 mg). The dry mycelial weight was significantly superior at pH 7 (230.21 mg), followed by pH 8 (215.18 mg). RAPD analysis revealed the maximum genetic similarity of 93 per cent between Gabbur (A7) and Sunkeshwarhal (A8) isolates, whereas the least similarity (40 per cent) was between Hattigudoor (A9) and Yaragatti (A13). The isolates were made into i.e., A cluster and B cluster. Stepdown regression led to the equation as Y = – 235.94 + 9.89X1 – 11.84X2 + 1.89X3 + 0.64X4 – 1.23X6 with R2 value of 0.78 including variables maximum temperature, minimum temperature, RH (morning), RH (evening) and rainy day. Fungi viz., Alternaria spp., Fusarium spp., Helminthosporium spp., Aspergillus spp., Penicillium spp., Rhizopus spp. and Mucor spp. were detected in infected seeds and survival studied for more than 14 months in refrigerator condition. The maximum per cent avoidable yield loss was recorded in Propiconazole (0.1%) at 35, 55, 75, 95, and 115 DAS. Yield reduction was 32.38 per cent in Bunny Bt caused by Alternaria leaf spot. Seed Treatment (ST) of Vitavax power (0.3%) + Foliar Spray (FS) with Propiconazole (0.1%) significantly lowered Alternaria leaf spot per cent disease index. However, the ST of Vitavax power (0.3%) + FS with Hexaconazole (0.1%) recorded highest incremental benefit: cost of 5.24. The T. viride (TV-97), seed treatment (0.8%) + foliar spray (0.8%) and Propiconazole, FS (0.1%) and both the treatments recorded highest and same incremental benefit: cost of 4.34. |
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Date |
2016-07-25T13:51:58Z
2016-07-25T13:51:58Z 2012 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/69772
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Format |
application/pdf
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