Penoxsulam + cyhalofop-butyl (premix) evaluation for control of complex weed flora in transplanted rice and its residual effects in rice-wheat cropping system

Abstract

Field experiments were conducted to evaluate the efficacy of penoxsulam 1.02% w/w (1.0% w/v) + cyhalofop-butyl 5.1% w/w (5.0% w/v) as post-emergence (PoE) in transplanted rice at CCS Haryana Agricultural University, Regional Research Station, Karnal during kharif 2010 to 2011, along with its phytotoxicity on rice crop (Kharif 2010 to 2012), residual phyto-toxicity on wheat crop (Rabi 2010–11 to 2012–13), its residual studies in soil, straw and rice grains in lab (2017) and also multi-locational adaptive trials on rice during Kharif 2017. Penoxsulam + cyhalofop 135 g/ha reduced the density and dry weight of Echinochloa crusgalli and other aerobic grassy weeds (0.0–3.3/m2 and 0.0–26.3 g/m2) and broad-leaf weeds (30.7–36.7/m2 and 0.0–4.7 g/m2) over its lower doses (105 and 120 g/ha) and was at par with its higher dose (150 g/ha), and it provided almost complete control of sedges during both the years. There was no significant effect of herbicidal treatments on the plant height and panicle length of the crop during both the years. Penoxsulam + cyhalofop 135 g/ha resulted in significantly higher number of effective tillers/mrl (49.0 in 2010 and 53.3 in 2011) than cyhalofop 80 g/ha (33.8.0 in 2010 and 49.8 in 2011) and weedy check (27.0 in 2010 and 32.5 in 2011), and penoxsulam + cyhalofop 105 g/ha during 2011 (46.5 in 2010 and 51.5 in 2011). The grain yield in plots treated with penoxsulam + cyhalofop 135 g/ha (5.46 t/ha in 2010 and 5.53 t/ha in 2011) was higher than its lower doses (105 and 120 g/ha) and at par with higher dose (150 g/ha) during both the years. Penoxsulam + cyhalofop 135 g/ha provided grain yields similar to penoxsulam 22.5 g/ha, pretilachlor 750 g/ha, butachlor 1500 g/ha and weed free check; and higher than cyhalofop 80 g/ha, bispyribac-sodium 20 g/ha and weedy check during both the years. Weeds growing throughout the crop season caused 68.8% and 45.8% reduction in the grain yield during 2010 and 2011, respectively. Penoxsulam + cyhalofop 135 g/ha provided net returns (‘ 24945–29325/ha) and B-C ratio (1.80–1.91) almost similar/higher to recommended PoE application of penoxsulam 22.5 g/ha (‘ 23756–29368/ha; 1.79–1.95). There was no phyto-toxicity of penoxsulam + cyhalofop even up to 600 g/ha on transplanted rice as well as succeeding wheat crop. Residues of penoxsulam + cyhalofop applied at 135 and 270 g/ha were below detectable level in soil, straw and grains of rice at harvest during 2010–11 to 2012–13. Penoxsulam + cyhalofop 135 g/ha applied at 15–20 DAT in rice (scented as well as coarse rice varieties) at 12 locations provided 92–97% control of weeds and average grain yield of 4.13 t/ha as compared to 3.83 t/ha in check herbicide bispyribac-sodium 25 g/ha. Penoxsulam + cyhalofop 135 g/ha resulted in average total monetary gain of ‘ 9665/ha and a net returns of ‘ 8465/ha.