Pesticide Research Journal

Field evaluation of imazethapyr and its ready-mix combinations with pendimethalin and imazamox for their effect on weeds and yield and economics of pea is reported. Twelve treatments viz., pendimethalin 750 g ha⁻¹ as pre-emergence, imazethapyr at 60 and 70 g ha⁻¹ as pre-emergence and at 70 and 80 g ha⁻¹ as early postemergence; pendimethalin + imazethapyr at 800 and 900 g ha⁻¹ as pre-emergence, imazethapyr + imazamox at 50, 60 and 70 g ha⁻¹ as post-emergence, hand weeding twice and weedy check were tested during three consecutive winters of 2014–15 to 2016–17 at Palampur. Avena ludoviciana (31.3%), Phalaris minor (31.3%) and Lolium temulentum (25%) were the major weeds. Application of imazethapyr at 80 g ha⁻¹ early post-emergence being at par with pre-emergence pendimethalin + imazethapyr at 800 or 900 g ha⁻¹ controlled the weeds effectively and resulted in highest green pea yield, net returns due to weed control and marginal benefit-cost ratio (MBCR). Early post emergence application of imazethapyr 80 g ha⁻¹ resulted in the highest weed control efficiency, weed management index, agronomic management index, and integrated weed management index, and the lowest weed index. Weeds reduced green pea yield by 80.2 per cent. With every g m⁻² increase in weed weight, the green pea yield decreased by 75.1 kg ha⁻¹. Based on the overall impact index, early post-emergence imazethapyr 70–80 g ha⁻¹, pre-emergence imazethapyr 60–70 g ha⁻¹ and pre-emergence ready-mix combination consisting of pendimethalin + imazethapyr at 800–900 g ha⁻¹ may be used for weed control in pea under Palam Valley conditions of Himachal Pradesh.