Weed control efficiency of pre- and post-emergence herbicides in pigeonpea (Cajanus cajan L.)

A field experiment was conducted during 2008–09 and 2010–11 to evaluate pre- and post-emergence herbicides alone or their integration on weed control in pigeonpea. Imazethapyr 75 g/ha applied at 20 days after sowing (DAS) significantly reduced the density anddry weight of both dicot and monocot weeds recorded at 30 DAS compared to weedy check followed by pendimethalin 0.75 kg/ha as pre-emergence. However, integration of paraquat 0.48 kg/ha with pendimethalin applied at 42 DAS caused significant reduction in the population as well as dry weight of the weeds at 50 and 70 DAS and was on par with hand weeding twice at 25 and 50 DAS. Higher weed control efficiency was also recorded with hand weeding twice (96.7%) followed by pendimethalin + paraquat at 42 DAS (78.3%). Uncontrolled weeds led to 79% loss in the seed yield of pigeonpea. Yet, application of pendimethalin followed by paraquat at 42 DAS registered higher seed yield (1304 kg/ha) which was at par with that in hand weeding twice at 25 and 50 DAS (1245 kg/ha). In addition, significantly more net return (27,035/ha) and benefit: cost ratio (3.28) were realized with the former treatment over the latter.