Resumo

ESQUEDA ESQUIVEL, Valentín Alberto  e  TOSQUY VALLE, Oscar Hugo. Chemical and mechanical weed control in rain-fed soybean. Agric. Téc. Méx [online]. 2006, vol.32, n.3, pp.353-358. ISSN 0568-2517.

In the tropics of Mexico weed competition is one of the major problems for rainfed soybean production. In 2003, a trial was established in the central region of Veracruz in order to determine the effectiveness of several herbicides and mechanical weeding on weed control and yield of soybean. Twelve treatments were designed with varied doses and combinations of the herbicides: clomazone, pendimethalin, bentazon, imazethapyr, fluazifop butil and fomesafen, two treatments of mechanical weeding and a weedy check. Except for pendimethalin, all tested herbicides had an efficient control of Lagascea mollis Cav. The highest control of Phyllanthus niruri L., was obtained with the two rates of imazethapyr tested and the mixture of fluazifop butil + fomesafen. Except for imazethapyr, Echinochloa colona (L.) Link was efficiently controlled by all herbicide treatments. Cyperus rotundus L. was controlled by two mechanical weedings, the treatments with clomazone and pendimethalin in pre-emergence complemented with bentazon at 21 days after emergence (DAE) and in a lesser degree by imazethapyr. The highest soybean yield was obtained from the treatment with imazethapyr at 75 g ha^-1; on the contrary, the yields obtained with pendimethalin and with a mechanical weeding at 15 DAE, were similar to that of the weedy check.

Palavras-chave : Glycine max (L.) Merr; Cyperus rotundus L; Echinochloa colona (L.) Link; Lagascea mollis Cav; Phyllanthus niruri L; herbicides.