1. Contribution from the Department of Agronomy, Gujarat Agrilultural University, Junagadh Campus, Junagadh-362 001 (Gujarat).
Field investigation was carried out on medium black soil, Gujarat Agricultural University, Junagadh from 1978–79 through 1980–81. Treatments comprised of post emergence chloroxuron (1.0 kg a.i.’ha), nitrofen (1.25 kg a.i./ha), methabenzthiozuron (1.40 kg a.i.fha) and pre plant diuron (0.80 kg a.i./ha) and fluchloralin (0.90 kg a.i.lha) alongwith local method (two hand weedings at 20 & 40 DAS) and control (No weeding). The results revealed that complete weed control was possible only by local method. However, where there is paucity of labour, spraying of fluchloralin at 0.90 kg a.i.’ha as pre planting + nitrofen 1.25 kg a.i./ha as post emergence 15 days after transplanting dissolved in 600 litres of water was found most effective and economic for timely weed control in onion with the highest weed control efficiency (96.43). This treatment yielded 37.56 t/ha mean buld yield which was comparable with the yield recorded under local method (38.49 t/ha) giving maximum net return of Rs. 1068 Wha.
