Selectivity and efficacy of herbicides to control volunteer soybean in castor crop.

Castor bean is an alternative to manu grain production areas, mainly as crop for the second season after soybean. In this scenario, there is demand for research on management of plants, resulting from remaining seeds of soybean after harvest. The objective of this work was to evaluate the selectivity and efficacy of post-emergence herbicides for the control of volunteer soybean in the castor crop. Two greenhouse experiments were carried out in a completely randomized design with four replications. The first assay was focused on the selectivity of herbicides to the castor, and the second to the efficacy of herbicides for soybean control. Evaluation of herbicide selectivity for the castor cultivar BRS Energia was carried out at 4 to 6 true leave stages. The treatments corresponded to two doses of ethoxysulfuron, halosulfuron-methyl, iodosulfuron-methyl, ioxynil, metamitron, oxadiazon and a control without any application. To evaluate the control efficacy of soybean cultivar BRS 3280RR in 3 trefoil stage, the treatments were comprised of two doses of ethoxysulfuron, halosulfuron-menthyl, metamitron and a control without application. The evaluations were: control, phytointoxication and plant height at 7, 14 and 21 DAA; stem diameter, leaf area, dry mass of aerial part and roots at 21 DAA. The results showed that herbicides ethoxysulfuron (60 and 80 g ha-1), halosulfuron-menthyl (75 and 112.5 g ha-1) and metamitron (2,800 and 4,200 g ha-1) were selective to castor. Ethoxysulfuron (60 and 80 g ha-1) and halosulfuron-menthyl (75 and 112.5 g ha-1) were effective for colunteer soybean control