Between 1996 and 1997, three experiments were carried out in order to evaluate the effect of the herbicide clomazone, alone and mixed with propanil and 2,4-D on weed control and toxicity to rice cv. Milagro Filipino, growing under upland conditions. All the experiments were established in Los Naranjos, in the Municipality of Tres Valles, in the state of Veracruz. The dominant weed species in the experimental plots were Cyperus iria, Echinochloa colona, Cyperus rotundus, Scleria setuloso-ciliata and Malachra fasciata. Clomazone applied preemergent, efficiently controlled E. colona at 0.72 and 0.96 kg a. i./ha, but its effect was partial and temporary on S. setuloso-ciliata and it had no effect on C. iria and C. rotundus. The mixture of clomazone + propanil + 2,4-D efficiently controlled E. colona and C. iria from 0.60 + 1.44 + 0.24 kg a. i./ha and had a good initial control of C. rotundus, but its effect disappeared 45 to 60 days after the application. Rice yields obtained from clomazone treatments, alone or mixed with propanil and 2,4-D were statistically similar to those of the regional controls.
Multi-year weed community dynamics and rice yields as influenced by tillage, crop establishment, and weed control: Implications for rice-maize rotations in the eastern Gangetic plains