Carry-over effect of weed management practices of maize (Zea mays) on weed dynamics and productivity of succeeding zero and conventional till wheat (Triticum aestivum)

Effective weed control in no-till systems is mainly based on herbicides. Appropriate weed management strategies can reduce the application of herbicides to a considerable extent. In this study, a possible weed management has been envisaged in zero-till (ZT) with and without residue, and conventional till (CT) wheat [Triticum aestivum (L.) emend. Fiori & Paol.] during 2010–11 and 2011–12 at Indian Agricultural Research Institute, New Delhi following residual effects of 12 weed control treatments, comprising of tank-mix and sequential application of herbicides in the previous rainy (kharif) seasons, 2010 and 2011 in maize (Zea mays L.). It was observed that total density of weeds did not differ significantly between weed control treatments adopted during previous rainy seasons. But, ZT with maize residue retention (ZT+R) caused a significant reduction on the population of grasses (e.g. Phalaris minor, Avena ludoviciana), broad-leaved (e.g. Chenopodium album, Melilotus indica) and total weeds compared to CT and ZT (without residue). Wheat yield was almost similar in all previous season tank-mix and sequential herbicide applications except that in weed-free check adopted during both the seasons in both years. But, the tank-mix pre-emergence application of pendimethalin 0.75 kg/ha + imazethapyr 0.050 kg/ha combined with ZT+R resulted in higher wheat yield, and was comparable with weed-free check, indicating its considerable residual effect on weeds in wheat. This tank-mix pre-emergence application of pendimethalin 0.75 kg/ha + imazethapyr 0.050 kg/ha when followed by ZT in wheat fetched higher net returns and net benefit:cost, which showed its superiority over other weed control treatments except weed-free check.