Soybean injury caused by the application of subdoses of 2,4-D or dicamba, in simulated drift.

2,4-D or dicamba can cause injuries and other deleterious effects on non-tolerant soybeans. Thus, the objective was to evaluate the potential for injury of subdoses of 2,4-D or dicamba, in drift simulation, for application in non-tolerant soybeans. Two experiments were carried out, one with 2,4-D and the other with dicamba. The treatments consisted of the application, in post-emergence of non-tolerant soybean, of subdoses 0; 1.35; 2.68; 5.37; 10.72; 21.45 and 42.9 g acid equivalent (ae) ha-1 2,4-D choline salt or dicamba diglycolamine (DGA) salt. Injury symptoms in plants, plant height and yield were evaluated, and the results were subjected to regression analysis. Polynomial fit was possible for the doses of both herbicides, with deleterious effects on soybean, with reductions in height and yield. The application of 2,4-D ≥ 10.72 g ae ha-1 was enough to cause injuries greater than 10% in plants, in simulated drift. The application of dicamba ≥1.35 g ae ha-1 was enough to cause injuries greater than 30% in plants, in simulated drift. For both herbicides, greater potential for injury and reductions in soybean yield were observed for the application of the highest doses (21.45 and 42.9 g ae ha-1).

Terbuthylazine herbicide: an alternative to atrazine for weed control in glyphosate-tolerant maize.

It is proposed that the herbicide terbuthylazine is more effective than atrazine in controlling weeds in maize. This study aimed to evaluate the efficacy of terbuthylazine and atrazine in a mixture with glyphosate in glyphosate-tolerant maize for post-emergence application. The experiment was conducted over three trials using randomized blocks with 4 repetitions and 10 treatments, composed by terbuthylazine rates + glyphosate, atrazine rates + glyphosate, [atrazine + mesotrione] + glyphosate, atrazine + tembotrione, isolated glyphosate, and nontreated control. Trial 1 were infested with Bidens subalternans DC. and Commelina benghalensis L; trial 2 with Urochloa plantaginea (Link) R. D. Webster, Ipomoea spp., volunteer soybean, B. subalternans, and grasses; and trial 3 infestation with C. benghalensis, U. plantaginea, Ipomoea spp., volunteer soybean, B. subalternans, Amaranthus hybridus L., and grasses. Weed control, crop injury, and yield were evaluated. Terbuthylazine + glyphosate showed an efficacy equivalent to that of atrazine or [atrazine + mesotrione] + glyphosate in the control of broadleaves and C. benghalensis. In contrast, the efficacy of terbuthylazine was similar or greater than that observed for atrazine in controlling grasses, depending on the location. Terbuthylazine is an important partner of glyphosate in controlling weeds in maize and is an alternative to atrazine.