SUPPRESSION OF Urochloa brizantha AND U. ruziziensis BY GLYPHOSATE UNDERDOSES

Abstract

Intercropping of Urochloa species with corn is an alternative to enable the no-tillage system, besides influencing weed community. Therefore, the investigation of underdoses of the herbicide glyphosate to manage grasses in intercropping systems, avoid grain yield losses, and make feasible intercropping in agricultural areas is important. This study aimed to evaluate glyphosate underdoses in the suppression of Urochloa brizantha cv. Marandu and Urochloa ruziziensis and weed control. Two tests were conducted under field conditions in a randomized block design with four replications and eight treatments consisting of increasing glyphosate doses (0, 54, 108, 270, 378, 540, 756, and 1.080 g a.e. ha−1). All treatments received a dose of 1.200 g a.i. ha−1 of atrazine. Evaluations of phytointoxication of brachiaria plants were carried out at 7, 14, 21, and 28 days after application. Moreover, total dry matter, leaf dry matter, stem dry matter, leaf to stem ratio, and canopy height of brachiaria plants and density and dry matter production of weed community were evaluated at 80 and 125 days after sowing. Glyphosate underdoses lower than 238 and 105 g a.e. ha−1 have potential to be investigated aiming at the management of U. brizantha cv. Marandu and U. ruziziensis, respectively.

Effects of glyphosate plus foliar manganese application on the production and quality of marandu grass

“…The F values recorded in this study were higher than those reported in a previous study in which the mathematical model indicated an F value of 1.11 for glyphosate doses of 54 and 108 g•a.e. ha -1 and control (Lima, Pereira, Sousa, Oliveira, & Jakelaitis, 2019). LSR is an important parameter for animal weight gain (Euclides et al, 2009), as a greater proportion of leaf blades is consumed during grazing (Bauer, Pacheco, Chichorro, Vasconcelos, & Pereira 2011).…”

Physiologic and morphologic characters of soybean and Urochloa sp. intercropped under reduced rates of glyphosate

“…The insecticide pyriproxyfen was applied at 9 DAE at a dose of 25 g ha -1 for controlling Bemisia tabaci race B. At 24 DAE, 120 g ha -1 glyphosate (Lima et al, 2019) was applied by means of a CO2 sprayer equipped with a 2.0 m boom, nozzles AXI 110 02, and a volume of spray solution of 160 L ha -1 . A wind speed of 1 m s -1 , relative humidity of 54.7%, and air temperature of 28.3 °C were registered at application time.…”

Luminous restriction and chemical control with glyphosate in integrated management of Urochloa brizantha L.

“…However, in many areas, U. brizantha is found as a weed that is difficult to control, causing economic and environmental damage (Santos et al, 2007;Silva et al, 2016;Lima et al, 2019). Additionally, it occurs as an invader of conservation areas worldwide, becoming a problem for the growth of native species of interest (Freitas et al, 2019).…”