Effect of sequential application of herbicides in transplanted onion (Allium Cepa L.)

Field experiments were conducted during kharif 2011 and 2012 at Main Horticultural Research and Extension Centre, University of Horticultural Sciences, Bagalkot, Karnataka to study the effect of sequential application of herbicides for weed management in transplanted onion under irrigated condition. Fifteen weed control treatments were tested in randomized block design replicated thrice. Among the herbicide treatments, application of oxyfluorfen @ 0.25 kg ha⁻¹ followed by (fb) oxyfluorfen 0.25 kg ha⁻¹ recorded significant reduction in broad leaved weed density and total weed density compared toall other treatment except weed free check. The weed control rating observed after pre emergence spray of oxyfluorfen @ 0.25 kg hafollowed by oxyfluorfen @ 0.25 kg ha⁻¹ and post emergence herbicides application revealed that, oxyfluorfen and hand weeding treatments resulted in excellent control of weeds at 7, 14, 21 and 28 days after spray. Though, weed free check, significantly reduced dry weight of weeds at all the stages, oxyfluorfen @ 0.25 kg ha⁻¹ followed by oxyfluorfen @ 0.25 kg ha⁻¹ was more effective in reducing weed dry weight. Farmer's practice of three hand weeding showed superior weed control index (WCI) at 30 days after transplantation(DAT) and at harvest, which was at par with oxyfluorfen @ 0.25 kg ha⁻¹ followed by oxyfluorfen @ 0.25 kg ha⁻¹. At 60 DAT, oxyfluorfen @ 0.25 kg ha⁻¹ followed by oxyfluorfen @ 0.25 kg ha⁻¹ recorded highest WCI. This herbicide treatment also recorded significantly higher bulb yield.