Study on the Action of Herbicide Combinations with Varying Irrigation Regimes for Control of Grassy Weeds in Wheat (Triticum aestivum L.)

Phalaris minor and Cynodon dactylon is the very problematic grassy weeds of wheat crop are responsible for significant yield reduction. Therefore, the present experiment was conducted at CSAUAT, Kanpur during Rabi season 2017-18 and 2018-19 in split-plot design with four replication having four irrigation regimes in main plot viz. irrigation at CRI and active tillering stage (I1), irrigation at CRI + jointing + booting (I2), CRI + active tillering + booting + flowering stage (I3) and  irrigation at CRI + jointing + booting + flowering + milking stage (I4), and eight factors of weed management (W1-weedy check, W2-two hand weeding at 20 and 40 days after sowing (DAS), W3-sulfosulfuron 25 gha-1at 35 DAS, W4- pendimethalin (pre-em) fb WCPL-15, 400 gha-1at 35 DAS, W5- broadway (carfentrazone ethyl 20% + sulfosulfuron 25%WG) 100 gha-1at 35 DAS, W6- halauxafen + penxasulam 23.5%, 75 gha-1at 35 DAS, W7- halauxafen - methyl 1.21% w/w + fluroxypyr at 35 DAS and W8- clodinafop- propargyl 15% + metsulfuron 1%, 400 gha-135 DAS) were allocated to sub plots for assessing the effect of these treatments on grassy weeds. Irrigations at crown root initiation (CRI) and active tillering stage (I1) significantly reduce the density and weight of grassy weeds with highest WCE and crop resistance index (CRI) over other irrigation regimes. However, I4 irrigation recorded highest weed effectiveness (WE) and crop dry matter yield (CDMY) followed by I3. All the weed management options are significantly superior over weedy check. Among herbicidal treatments, lowest weed density and their weight, WE and the highest WCE, CRI, WPI and CDMY was recorded with the application of broadway (W5) followed by W8. Reducing irrigation frequency and the post emergence application of broadway are the best option for managing grassy weeds in wheat, but for higher CDMY more number of irrigations required.