Abstract
The objective of this work is to propose a chemical management alternative to control <i>Bidens pilosa</i> and <i>Euphorbia heterophylla</i> in genetically modified soybean without affecting grain production and seed germination by using glyphosate applied only once and in mixture, aiming to reduce the number of applications and the amount of herbicides used. The experimental design was randomized blocks with 10 treatments and 4 replications. The soybean used was BRS-Valiosa RR. The treatments consisted of glyphosate and chlorimuron-ethyl applied once and alone (1.5; 2.0 and 80 L or g ha<sup>-1</sup> pc), glyphosate in mixture with chlorimuron-ethyl (1.5+10 and 2.0+10 L or g ha<sup>-1</sup> pc) and sequentially applied glyphosate (1.5/1.5; 2.0/1.5 and 2.0/1.5/1.5 L ha<sup>-1</sup> pc), plus weeded (clean) and non-weeded (dirty) witnesses. The evaluations were: herbicide efficacy in <i>B. pilosa</i> and <i>E. heterophylla</i>, phytotoxicity, density, height and grain yield (kg ha<sup>-1</sup>) in soybean. The production data obtained were subjected to analysis of variance and F test by the SANEST program (P<0.05). It was concluded that the studied species, <i>B. pilosa</i> and <i>E. heterophylla</i>, were controlled by glyphosate at levels above 90%. There was no visual injury in soybean and no significant decrease in production and germination.
Highlights
The methods commonly used for weed control are mechanical, crop and chemical
The treatments consisted of glyphosate Roundup Ready® commercial product containing 480 g L-1 acid equivalent and chlorimuron-ethyl Classic® commercial product containing 80 g kg-1 active ingredient applied once and alone (1.5; 2,0 and 80 L or g ha-1 pc), glyphosate mixed with chlorimuron-ethyl (1.5+10 and 2.0+10 L or g ha-1 pc) and sequentially (1.5/1.5; 2.0/1.5 and 2.0/1.5/1.5 L ha-1 pc), in addition to weeded and nonweeded controls
Glyphosate and chlorimuron-ethyl herbicides were applied once and alone and glyphosate mixed with chlorimuron-ethyl were carried out on 01/19/07, 14 days after emergence (DAE) of soybean (01/05) at the phenological stage V2, according to the classification of Fehr et al (1971)
Summary
The methods commonly used for weed control are mechanical, crop and chemical. For example, do not control some broadleaved plants and some pre-emergent plants have a prolonged residual effect and may cause phytotoxicity in crops that are planted in succession; This drawback is even more pronounced in regions where safrinha maize is cultivated [20]. Another point to be highlighted is that the cost in this type of control is high because it is necessary to enter the field at least twice and the operation can cause greater mechanical damage to soybean plants and soil compaction
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