Chemical weed control studies under sole and intercropping systems in groundnut (Arachis hypogaea L.).
Field experiments were carried out at Bangalore during kharif 1989 and 1990, to screen herbicides under different cropping systems in groundnut (Arachis hypogaea). Yield studies indicated that groundnut sole crop gave highest pod yield (997 kg/ha) as compared to groundnut-red gram [pigeon peas] (4:1) (947 kg/ha) and groundnut-sunflower (4:1) (881 kg/ha) intercrops. Hand weeding twice (20 + 40 days after sowing (DAS)) + hoeing 45 DAS gave maximum pod yield (1256 kg/ha) followed by pre-em. application of alachlor at 1.5 kg a.i./ha (1182 kg/ha) and other herbicides (783 to 1040 kg/ha). Manual weeding gave excellent control of all types of weeds while alachlor at 1.5 kg a.i./ha, fluchloralin at 1.02 kg a.i./ha, trifluralin at 1.0 kg a.i./ha and pendimethalin (0.5 or 1.0 kg a.i./ha) gave moderate to good control of most monocotyledonous weeds and few small seeded, broadleaved weeds, while flu[a]zifop-butyl was ineffective on dicotyledonous weeds and sedges, thus, resulting in lower yields. None of the herbicides were effective against Acanthospermum hispidum.