Bioefficacy of herbicides in blackgram and their residual effect on succeeding mustard

Pre-emergence application of imazethapyr + pendimethalin at 1000 g/ha provided excellent control (90%) of T. portulacastrum up to 30 DAS. At 60 DAS, per cent control with this treatment decreased to 73% which was at par with two hoeings employed at 20 and 40 DAS and pendimethalin at 1000 g/ha. Post-emergence use of imazethapyr + imazamox at 60–80 g/ha exhibited 78–83% control of weeds with slight crop suppression which mitigated within 10–15 days after spray but with yield penalty. Early postemergence application of imazethapyr at 50, 60 and 70 g/ha also caused mild injury to blackgram in terms of yellowing of leaves and stunted crop growth up to 30 DAS, but it diminished within two weeks. Maximum seed yield (0.90 t/ha) of blackgram was obtained with two hoeings at 20 and 40 DAS which was at par with imazethapyr + pendimethalin at 1000 g/ha and pendimethalin at 1000 g/ha applied as preemergence. All herbicides, irrespective of their dose and time of application, did not cause any injury to mustard planted as succeeding crop after harvest of blackgram.