Integrated weed management in rainy season sorghum (Sorghum bicolor)

A field experiment was carried out during the rainy season of 2011 and 2012 in Vertisols at Dharwad, Karnataka, to develop integrated weed management for hybrid sorghum [ Sorghum bicolor (L.) Moench] with pre- emergence application of atrazine @ 0.5 kg/ha, post-emergence application of atrazine @ 0.75 kg/ha, 2, 4-D @ 0.5 kg/ha, metsulfuron methyl @ 4 g and 6 g/ha, intercultivation and hand-weeding. The maximum average grain yield (4.42 t/ha) was recorded with pre-emergence application of atrazine @ 0.5 kg/ha, followed by post-emer- gence application of 2, 4-D @ 0.75 kg/ha at 20 days after sowing and interculturing at 30 days after sowing, which was at par with weed free treatment and increased the yield by 39.8% over weedy check and 6.5% over farmers practice. The higher grain yield may be owing to significantly lower weed dry weight, higher weed-control effi- ciency and higher nutrient uptake by sorghum which reflected in higher values of grain weight/ear, ear length and 1,000-grain weight. In weedy check, weeds removed 20.5 kg N/ha, 14.9 kg P/ha and 22.3 kg K/ha, being higher than rest of the weed-management practices. Maximum net returns ( 29,530/ha) and benefit: cost ratio (2.43) were realized with atrazine @ 0.5 kg/ha (PE), followed by 2, 4-D @ 0.75 kg/ha (PoE) at 20 days after sowing and intercultivation at 30 days after sowing.