Mixtures of broadleaf herbicides and glyphosate have been adopted during post-emergence weed control in RR® soybeans mainly to improve the efficacy of this herbicide when applied on tolerant weeds, to provide residual weed control or to prevent the selection of resistant biotypes. This work aimed to evaluate the efficacy of glyphosate alone or in tank mixtures with other broadleaf herbicides to control Euphorbia heterophylla and Ipomoea grandifolia, at two growth stages (1-to-3 leaves and 4-to-6 leaves). Thus, four greenhouse assays were carried out: glyphosate (480 and 960 g a.e. ha-1) applied alone or combined in tank mixtures with chloransulam-methyl (30.24 g ha-1 ), chlorimuron-ethyl (12.5 g ha-1 ), imazethapyr (80 g ha-1 ), fomesafen (62.5 g ha-1 ), lactofen (72.0 g ha -1), flumiclorac-pentyl (30.0 g ha-1 ) and bentazon (480 g ha-1 ). All experiments were arranged in a randomized block design, with four replicates. For both weeds, the use of 960 g ha-1 of glyphosate alone was sufficient, when application was performed at 1-3 leaf stage. For applications performed at 4-6 leaf stage for E. heterophylla, increased weed control in relation to glyphosate applied alone can be achieved by using mixtures with protox inhibitors. In relation to I. grandifolia at the 4 6 leaf stage, fomesafen and flumiclorac-penthyl decreased weed control when added to glyphosate at 480 g a.e. h-1. On the other hand, mixtures containing glyphosate at 960 g a.e. ha-1 provided increased weed control. In general, control of E. heterophylla and I. grandifolia was improved when herbicide treatments were applied at 1-3 leaf stage, either using glyphosate alone or mixed with other broadleaf herbicides.
morningglory; Glycine max; wild poinsettia; herbicides; glyphosate resistant soybean
