HERBICIDE SELECTIVITY TO SIGNAL GRASS AND CONGO GRASS

Arnon Henrique Campos Anésio ,L.D Tuffi Santos,Rodrigo Richard Da Silveira ,T.g.s Braz ,E.a Ferreira ,Maurinho Luiz Dos Santos ,José Barbosa Dos Santos

doi:10.1590/s0100-83582017350100062

Arnon Henrique Campos Anésio , L.D Tuffi Santos + Show 5 more

Open Access

https://doi.org/10.1590/s0100-83582017350100062

Copy DOI

Abstract

ABSTRACT This study was conducted in order to evaluate the selectivity of signal grass and congo grass, submitted to post-emergence herbicide application. The experiment was conducted under greenhouse conditions, in Diamantina, Minas Gerais state, and it was arranged in a randomized block design, with five replications. Treatments were set in factor scheme (8 x 2) + 2. Eight herbicides (nicosulfuron; clomazone; glyphosate; fluazifop-p-butyl + fomesafen; lactofen; fomesafen; fluazifop-p-butyl and mesotrione) were applied in doses recommended by the manufacturer on two fodder species: Brachiaria decumbens cv. Basilisk (signal grass) and Brachiaria ruziziensis (congo grass); in addition, there were two control samples without herbicide application, for a total of 18 treatments. The evaluated herbicides showed less intoxication on signal grass when compared to congo grass. Nicosulfuron and glyphosate promoted higher intoxication on both species when compared to the other herbicides. Glyphosate, fluazifop-p-butyl + fomesafen, fluazifop-p-butyl, mesotrione and nicosulfuron affected the ratio variable / maximum fluorescence (Fv/Fm) in both species, indicating an effect provided by these herbicides on the electron transport chain. Results demonstrated that signal grass and congo grass have higher susceptibility to glyphosate, fluazifop-p-butyl + fomesafen, fluazifop-p-butyl, mesotrione and nicosulfuron. congo grass shows higher susceptibility to the studied herbicides when compared to signal grass.

Highlights

In the current Brazilian ruminant production system, pastures constitute the main food source, being the most practical and less expensive way, affordable by all cattle breeders
This study was conducted in order to evaluate the selectivity of signal grass and congo grass, submitted to post-emergence herbicide application
An increase in the average values of intoxication was observed for the two evaluated species, with the application time, when lactofen was applied; the highest intoxication values were observed for signal grass (59%), compared to congo grass (41%), on day 30 DAA (Figure 1)

Summary

Introduction

In the current Brazilian ruminant production system, pastures constitute the main food source, being the most practical and less expensive way, affordable by all cattle breeders. The great amount of degraded pastures has caused damages the production system of grazing ruminants, due to the decrease in productivity and quality of fodder, pest and disease infestation and weed presence (Gimenes et al, 2011). The interference created by weeds in pastures is one of the factors that most negatively affect animal productivity. The use of herbicides is an important practice to minimize the negative effects caused by weeds in pastures, because of its application speed and need for little labor. Its effectiveness depends on different variables, among which the weed species that need to be controlled in the pasture (Gimenes et al, 2011)

Objectives

Methods

Results