Weed management in rapeseed-mustard -A review

Rapeseed-mustard is an important group of edible oilseed crops in India. Technological advancement in rapeseed-mustard production has resulted in increased productivity. But many biotic stresses such as weeds cause severe yield losses up to 45% in rapeseed-mustard. They reduce crop productivity and quality by competing with crop plants for available nutrients, water, land and light resources and also influence the agro-ecosystem. A variety of weeds affects these crops but the extent of damage in terms of yield and resources is location specific. Many of the weeds are specific to crop and/ or location, Orobanche aegytptica is becoming great menace in rainfed areas of Rajasthan, Madhya Pradesh and Haryana, whereas, Chenopodium, Asphodelus, Melilotus and Trianthema spp. cause serious yield losses in other areas. Unlike other oilseed crops, mustard suffers more from weed competition in early growth stages especially between 20-40 days after sowing. The weed management in mustard is done by both cultural and herbicidal approaches. Different dinitroaniline herbicides are commonly used to eliminate weed species and most of these are effective against only narrow range of weed species. Thus, integration of herbicide at critical growth stages with one or two hand weeding at proper time for improving the weed suppressing effect of crop gives significant improvement in crop yield. Economic analysis revealed that fluchloralin and pendimethalin alone or in combination with hand weeding at 30 days after sowing was the most economical.