Chemical weed control in direct-seeded rice (Oryza sativa) with or without sequential application of 2,4-D (EE)

A field investigation was carried out during the rainy seasons of 2001 and 2002 with various herbicides, applied alone or followed by sequential application of 2,4-D (EE), to test their bio-efficiency in controlling weeds in direct- seed rice (Oryza sativa L) sown on well-prepared seed bed. All the herbicidal treatments increased grain yield of the crop significantly over unweeded check while decreasing population and dry weight of the weeds but remained inferior to weed-free treatment. Uncontrolled growth of weeds caused 64.2 to 67.4% reduction in the crop yield compared to weed-free treatment. Among the herbicides, pendimethalin 1.00 kg/ha (pre-emergence) + 2,4-D (EE) 0.50 kg/ha (21 DAS), while remaining at par with anilophos 0.40 kg/ha (early post-emergence) + 2,4-D(EE) 0.50 kg/ha (21 DAS), gave the highest yield. The same treatment also resulted maximum reduction in density and growth of the weeds. Application of pendimethalin and anilophos in combination with 2,4-D(EE) proved significantly better than their single application.