Effective post-emergence herbicides for weed control in rice nurseries

On farm experiments were conducted during Kharif seasons of 2011 and 2012 to study efficacy of postemergence herbicides bispyribac-sodium 25 g/ha for broad-spectrum weed control in rice nursery. Among the different treatments, post-emergence application of bispyribac-sodium 25 g/ha applied at 15 DAS (days after sowing) significantly reduced total weed density with weed control efficiency of 90.9 to 97.6% for Echinochloa crus-galli, Trianthema portulacastrum and Cyperus iria. Among other treatments, pre-emergence application of pretilachlor + safener 0.15 kg/ha also recorded significantly lower weed density as compared to control (unweeded). Although weed control efficiency of this treatment was relatively higher for E. crus-galli (84.7%) but for T. portulacastrum and C. iria, this treatment recorded weed control efficiency of 75.9 and 71.2%, respectively. Farmers practice (increased seed rate 100 g/m²) also recoded significantly lower weed density as compared to control (unweeded) but the weed control efficiency was quite low against E. crus-galli (36.8%) and C. iria (28.1%); however, it was relatively higher for T portulacastrum (66.0%) with mean of 43.7%.