Influence of chemical weed control on weed dynamics in field bean.
A field experiment was conducted during summer [year not given] at Hebbal, Bangalore, Karnataka, India, to study the weed dynamics as influenced by various herbicides, i.e. fluchloralin (0.75, 1.00, and 1.25 kg/ha), alachlor (1.00, 1.50, and 2.00 kg/ha), pendimethalin (0.75, 1.00, and 1.25 kg/ha), and metolachlor (0.75, 1.00, and 1.25 kg/ha). Significantly lower total weed population (3.95/0.25 m2) and weed dry weight (3.15 g/0.25 m2) was obtained with hand weeding twice. Among the herbicides, fluchloralin at 1.0 and 1.25 kg ha-1 and metolachlor at 0.75 kg ha-1 produced lower total weed population and weed dry weight. These treatments also reduced the number of monocots, sedges, and dicot weeds and their dry weight. However, Cynodon dactylon, Cyperus rotundus, and Acanthospermum hispidum were not controlled effectively by any of these herbicides; their population was increased by 58-61, 42-62, and 60-85%, respectively. Weed control efficiency was higher in hand-weeded twice (84.1%), followed by fluchloralin 1.0 and 1.25 kg ha-1 (58 and 53.9%) and metolachlor 0.75 kg ha-1 (52%) which ultimately resulted in higher seed yield of field bean (Lablab purpureus) .