Weed control studies in spring planted sugarcane.
In field trials on clay in 1988-90, 7 herbicide treatments, manual weeding 3 times and mulching were evaluated for the control of weeds (mainly Cyperus rotundus, Echinochloa crus-galli and Cynodon dactylon) in sugarcane cv. CoS. 767. All treatments reduced weed DW from an av. weedy control value of 451.46 g/m2 to 100.49, 281.98 and 152.06-360.53 g by manual weeding, mulching and herbicides, resp. The best herbicide treatment was pre-em. atrazine at 1 kg/ha, followed 6-8 weeks after planting by 1 kg glyphosate. The av. cane yield was increased from 52.84 t/ha to 74.63, 62.14 and 56.17-70.80 t by manual weeding, mulching and herbicides, resp.; the atrazine + glyphosate treatment was the most effective herbicide treatment. This herbicide treatment also resulted in the highest sucrose and commercial cane sugar recoveries and benefit:cost ratio of all treatments (14.78%, 7.26 t/ha and 5.03, resp.).