Controle de alecrim do campo (Vernonia nudiflora) em pastagem natural com aplicação localizada de herbicidas em diferentes doses

Abstract

With the objective to evaluate the effect of local application of herbicides in grassland vegetation to control of alecrim do campo, was conducted a study in 2006/07 in a private property, located in district of Santa Flora municipality of Santa Maria, physiographic region of the Depressão Central of Rio Grande do Sul. The experimental design was a split plot arranged in blocks with three replications in a factorial arrangement of (5x3)+1, five herbicides with three doses and the control. The plots corresponded to the herbicides, been located the doses in zero; 360 +96; 720 +192 and 1080 +288 g ha-1 of acid equivalent (a. e.) of 2.4-D + picloran; zero; 1005, 2010 and 3015 g ha -1 of the a. e. of 2.4 D; zero; 720; 1440 and 2160 g ha-1 of a. e. of triclopyr; zero; 90 +90; 180 +180 and 270 +270 g ha-1 of a. e. of 2.4 D + picloran and zero; 120 +120; 240 +240 and 360 +360 g ha-1 of a. e. fluroxipir + picloran. The subplots were composed by 8 tables arranged on a flat line, where were made a survey prior to application, one 60 and another 353 days after application (DAA). For the herbicides application were used a "Chemical Applicator." The results showed that all herbicides had significant difference in reducing the number of stems of alecrim do campo in relation to the control, and there was no significant difference between the herbicides. All herbicides showed a significant difference in reducing the abundance of alecrim do campo from the field, in relation to the control in 60 and 353 DAA. In the first survey there was no significant difference between treatments in relation to the average heights of alecrim do campo stems. In the third survey, 353 DAA, the herbicide fluroxipir + picloran located in dose 360+360 g e.a ha-1 showed a greater reduction in height.