Abstract

The field experiments were conducted during kharif and rabi 2014 to study the efficacy of pre-mix herbicide mixture penoxsulam+cyhalofop butyl for weed control in direct seeded puddled rice. The experiment was laid out in randomized block design with eight treatments and three replications. The treatments comprised four different doses of penoxsulam+cyhalofop butyl 6% OD viz., 120, 125, 130 and 135 g a. i./ha, bispyribac sodium 10% SE 25 g a. i./ha, penoxsulam 24 SC 22.5 g a. i./ha, hand weeding twice and weedy check. On 30 days after sowing (DAS) weed flora comprised sedges (53.91%), broad leaf weeds (37.88%) and grasses (8. 2%) and on 60 DAS weed flora constituted sedges (53.15%), broad leaf weeds (BLW) (34.66%) and grasses (12.19%). The dominant weed species present in the experimental field were Schoenoplectus juncoides (Roxb.) Palla, Cyperus iria L. and Cyperus difformis L. among sedges; Isachne miliaceae Roth among grasses and Ludwigia perennis, Limnocharis flava (L.) Buch., Marsilea quadrifoliata L. and Bergia carpensis L. among broad leaf weeds. Pre-mix herbicide mixture, penoxsulam+cyhalofop butyl was found to be effective in reducing the density and dry weight of weeds at 30, 45 and 60 DAS. Among the doses, higher doses of penoxsulam+cyhalofop butyl (130 and 135 g a. i./ha) were found to be more effective in reducing the dry weight with a weed control efficiency of 97.34 and 98.31%, respectively. Higher growth and better expression of yield attributes were registered for these treatments. Adoption of weed control measures enhanced the grain yield from 4.26 to 8.46 t/ha. All the tested doses of penoxsulam+cyhalofop butyl recorded higher grain yield compared to hand weeding, penoxsulam and bispyribac sodium applied alone. Application of penoxsulam +cyhalofop butyl at its higher dose (135 g a. i./ha) recorded the highest grain yield which was on a par with its lower dose 130 g a. i./ha. The highest gross returns and B: C ratio were also recorded by these treatments. Bispyribac sodium was found to be less effective in reducing the density and dry weight of sedges resulting in lesser yield and B: C ratio compared to penoxsulam in the present study. Hand weeding recorded the lowest gross returns and B: C ratio among the weed control treatments. The study concludes that better broad spectrum control of weeds can be achieved by the post-emergence application of herbicide mixture penoxsulam+cyhalofop butyl on 15 DAS. The selection of herbicide and dose should depend on the target weed species in an area.