WEED CONTROL EFFICACY OF PRE-EMERGENCE HERBICIDES IN PUDDLE TRANSPLANTED RICE

Abstract

Pre-emergence herbicides inhibit weed emergence and reduces the weed growth at early phase of the crop growth in transplanted lowland rice. Selection of pre-emergence herbicides of different mode of action and their rotational use reduces risk of herbicide resistance development in weeds. The experiment included thirteen herbicides for pre-emergence application, Pyrazosulfuran ethyl as early post emergence (EP) application along with a weed free and a weedy check as control. The experiment was laid out in a randomized complete block design with three replications. The results revealed that Pretilachlor, Pendimethalin, Butachlor, Penoxulam, and Carfentrazon ethyl provided best weed control (73-79%), while Pyrazosulfuran both as pre-emergence and early post emergence, Oxadiargyl, Metamiphop, Metribuzin, and Oxadiazone gave moderate (50-63%) weed control in transplanted rice. Among the herbicides, Triasulfuran gave only 30% weed control and exerted toxic effects on rice plant and reduced yield of crop. Different pre-emergence herbicides gave similar yield such as Butachlor (5.81 t ha⁻¹), Pretilachor (5.66 t ha⁻¹), Carfentrazol ethyl (5.58 t ha⁻¹), Orthosulfamuron (5.53 t ha⁻¹), and Ethoxysulfuron (5.46 t ha⁻¹) to that of weed free plots (5.98 t ha⁻¹).  From the present study it appeared that pre-emergence herbicides of any of the four groups such as (i) Butachlor or (ii) Pretilachlor or (iii) Carfentrazon ethyl or (iv) Orthosulfamuron, Penoxulum, and Ethoxysulfuron could be used for successful weed control in puddle transplanted rice and the alternate use of these herbicides could be an effective tool for avoiding herbicide resistance development in weeds.