Influence of Chemical Herbicides on Weed Management in Mustard–Lentil Intercropping Systems: A Review

Abstract

Mustard (Brassica juncea) & lentil (Lens culinaris) intercropping is an agronomically and nutritionally important rabi-season production system in South Asia, offering advantages in land-use efficiency, resource capture, and farm resilience. However, its productivity is severely constrained by intense weed pressure arising from slow early crop growth, open canopy structure, and asynchronous resource demand between component crops. This review critically synthesises existing research on weed flora, herbicide efficacy, crop selectivity, phytotoxicity, and agroecological consequences of chemical weed management in mustard–lentil intercropping systems. Dominant winter weeds, including Chenopodium album, Anagallis arvensis, Coronopus didymus, and Phalaris minor, cause substantial yield losses when not effectively managed. Pre-emergence herbicides such as pendimethalin, oxyfluorfen, and oxadiargyl and selective post-emergence herbicides including ALS- and ACCase-inhibitors remain central to weed control, yet their use in intercropping demands exceptional precision due to the high herbicide sensitivity of lentil. Evidence indicates that inappropriate dose, timing, or broadcast application can induce phytotoxicity, suppress nodulation, and compromise system productivity. The review highlights the importance of spatially selective application methods, herbicide rotation, and integration with cultural and mechanical practices to enhance selectivity, delay resistance evolution, and safeguard soil biological health. Emerging challenges, including herbicide resistance, residue carryover, and environmental and human-health risks, underscore the limitations of chemical-only strategies. Consequently, integrated weed management (IWM), combining judicious herbicide use with optimised crop geometry, mechanical weeding, and ecological intensification, is identified as the most resilient pathway for sustainable mustard–lentil intercropping. The review concludes by identifying critical knowledge gaps and research priorities necessary to refine herbicide stewardship and improve system-level productivity, profitability, and environmental sustainability.