HERBICIDAS RESIDUAIS NO CONTROLE DE ELEUSINE INDICA E NA SELETIVIDADE DA CULTURA DA SOJA

Abstract

The selection of herbicide-resistant weed biotypes in the world has increased significantly in recent years, especially in relation to glyphosate, among which is the goosegrass (Eleusine indica L. Gaertn), that has become a species difficult to control and is present in most soybean producing regions of Brazil. Thus, the objective of this work was to evaluate the efficiency of residual herbicides in goosegrass control and soybean crop selectivity in soils with different textural classess. For this, four experiments were conducted under field conditions, two to determine herbicide efficacy and two for selectivity, which were divided into two chapters to better understand the results. The experimental design was a randomized block design with four replications, containing the herbicides trifluralin (1200 g i.a ha-1), s-metolachlor (960 g i.a ha-1), diclosulam (29,4 g i.a ha-1), imazethapyr + flumioxazin (100 + 50 g i.a ha-1), sulfentrazone (150 g i.a ha-1), sulfentrazone + diuron (140 + 280 g i.a ha-1), clomazone (800 g i.a ha-1) and chlorimuron-ethyl (20 g i.a ha-1). For control efficacy experiments two control (weeding and without weeding) were used and in the selectivity experiments one control without herbicide. Herbicide control efficiency was determined by visual evaluation of control at 14, 21, 28 and 35 days after application and for selectivity, we analyzed the visual phytotoxicity of soybean plants at 7, 14, 21 and 28 days after emergence. In addition, the agronomic and crop production components were evaluated. The use of residual herbicides is an important tool in the management of goosegrass, reducing initial competition with the crop. However, the texture and organic matter of the soil influenced the control and mainly the herbicide selectivity. Overall, s-metolachlor, clomazone and trifluralin were more efficient in controlling goosegrass and did not cause injury to soybean.