Efficacy and selectivity of tank mixtures of preemergence herbicides in no-till soybean.

Conduziu-se um ensaio na Fazenda Bela Vista, município de Serranópolis-GO, com o objetivo de avaliar a eficiência e seletividade das combinações de herbicidas aplicadas em pré-emergência da soja cv. Rainha. Os tratamentos utilizados foram: metolachlor+diclosulam (2400+35 g/ha), sulfentrazone+diclosulam (250+25, 300+20, 350+ 15 e 200+35 g/ha), clomazone+diclosulam (504+25, 720+25, 828+25, 504+30, 720+30 e 828+30 g/ha), além da testemunha sem capina. As misturas dos herbicidas foram seletivas para a soja cv. Rainha. Sulfentrazone+diclosulam e clomazone+diclosulam, independentemente das doses utilizadas, proporcionaram eficiente controle do capim-carrapicho (Cenchrus echinatus), picão-preto (Bidens pilosa), trapoeraba (Commelina benghalensis), leiteiro (Euphorbia heterophylla) e guanxuma (Sida rhombifolia), equivalendo-se a metolachlor+diclosulam (2400+35 g/ha). Não foram observadas diferenças significativas entre as produtividades nos diversos tratamentos químicos, mas o rendimento foi menor na testemunha sem capina, O peso da matéria seca das plantas daninhas na testemunha foi significativamente superior àqueles obtidos nos tratamentos químicos. A trial was carried out on Bela Vista Farm, Serranópolis (GO), to evaluate the efficiency and selectiveness ofherbicide combinations applied in preemergence for soybean cv. Rainha. The treatments used were: metalochlor+diclosulam (2400+35 g/ha), sulfentrazone+diclosulam (250+25, 300+20, 350+ 15 and 200+35 g/ha), clomazone+diclosulam (504+25, 720+25, 828+25, 504+30, 720+30 and 828+30 g/ha), as well as an untreated control. It was concluded that the herbicide mixtures were selective for soybean cv. Rainha. Sulfentrazone+diclosulam and clomazone+diclosulam, independently ofthe dose used showed an efficient control of capim-carrapicho (Cenchrus echinatus), picão-preto (Bidens pilosa), trapoeraba (Commelina benghalensis), leiteiro (Euphorbia heterophylla) and guanxuma (Sida rhombifolia), close to that ofmetolachlor+diclosulam (2400+35 glha). The lowest bean yield was obtained with the untreated control. Significant differences betwen the chemical treatments for productivity were not observed but the lowest bean yield was obtained with the untreated control. The dry weight of weeds in the untreated control was superior to that obtained with chemical treatments.