Field Evaluation of Some Selected Chemicals against Bacterial Blight in Cotton

The aim of this study is to evaluate the comparative efficacy of some selected chemicals and antibiotic in controlling bacterial blight of cotton variety CB-9 in vivo. A field experiment was carried out at the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to study efficacy of selected chemicals against bacterial blight of cotton with ten treatments arranged in Randomized Complete Block Design (RCBD).Cotton plant was affected by bacterial blight at all stages of its development. The disease spread from the cotyledons to the leaves followed by the main stems, branches and bolls. Field evaluation of selected chemicals revealed that Streptomycin Sulphate was highly effective against bacterial blight of cotton caused by Xanthomonas axonopodis pv. malvacearum. The highest germination (92%) was found in the treatment where cotton seed was treated with Streptomycin Sulphate at 0.15% which was followed by seed treatment with Streptomycin Sulphate at 0.15% + Foliar spray with Streptomycin Sulphate at 150 ppm. The lowest disease severity in terms of PDI (22.66%) was found in Seed treatment with Streptomycin Sulphate at 0.15% + Foliar spray with Streptomycin Sulphate at 150 ppm subsequently after three foliar sprays at 105 DAS. Seed treatment with Streptomycin Sulphate at 0.15% + Foliar spray with Streptomycin Sulphate at 150 ppm reduced the disease severity by 44.46% over control and increased the yield of seed cotton 34.58% over control. Streptomycin Sulphate showed higher affectivity against bacterial blight of cotton compared with other tested fungicides.