Glyphosate Herbicide Use in Urochloa brizantha Management in Intercropping With Herbicide-Resistant Maize

Abstract

The success of the intercropping among cultivated species depends on the adoption of practices that provide, in due course, greater competitive ability of a species over another. The objective of this study was to evaluate the use of glyphosate herbicide in the suppression of Brachiaria (signalgrass) intercropped with maize. The experiment was conducted in a randomized complete block design with four replications. The treatments were arranged in a 5 x 2 + 2 factorial arrangement, the first factor corresponding to the doses of glyphosate (48, 96, 144, 240, 480 g ha-1 of the acid equivalent (a.e)) and the second one to the vegetative stages of the signalgrass at the time of application (2 and 4 tillers). Two controls were added to the treatment list, comprising controls without herbicide application and hand removal of the signalgrass. The number of plants, tillers and dry matter of signalgrass was reduced with glyphosate. The increase of the glyphosate doses enhanced the injure to the forage plants, mainly when the compound was sprayed at the two-tiller vegetative stage. The dry matter of maize plants increased proportionally to the glyphosate dose. However, the height of the maize plants was not affected. The grain mass and productivity of maize grain increased with increasing dose of glyphosate. The maize yield was negatively influenced on the untreated control. Glyphosate at 96 and 144 g ha-1, when applied at 2 and 4 tiller stage, respectively, reduces the growth of signalgrass and does not affect the maize grain yield.

MANAGEMENT OF Urochloa ruziziensis WITH GLYPHOSATE IN INTEGRATED SYSTEM WITH GLYPHOSATE-RESISTANT CORN

“…L -1 of N-(phosphonomethyl) glycine, and nicosulfuron with 40 g a.i. L -1 , expressing the concentration of each product as usual in the literature (Cavalieri et al, 2008;Freitas et al, 2015;Silva et al, 2016;Silveira et al, 2017;Machado et al, 2018). Fertilization was carried out to meet the corn crop requirements with the application of 320 kg ha -1 of formulated fertilizer 5-25-15, which provided 16 kg of N 2 , 60 kg of P 2 O 5, and 48 kg of K 2 O, according to Vilela et al (2002).…”

“…The adoption of this intercropping system is a management alternative that provides greater rationality in resource utilization, including time, and reduces weed infestation (Santos et al, 2008;Borges et al, 2014;Timossi et al, 2018). Competition between crop and forage and the resulting scarcity of development factors will occur, and it is necessary to balance the competitive capabilities of the species with the suppression of the forage through the herbicide application (Silva et al, 2016).…”

Efeito Do Estádio De Desenvolvimento E Doses De Herbicida Na Supressão De Crescimento De Urochloa Ruziziensis

“…A ausência de diferença entre os tratamentos, para número de perfilhos das plantas, indicou que as doses testadas seriam insuficientes para suprimir o desenvolvimento desta variável, o que de certo modo, contraria o observado por Silva et al (2016) que afirmaram que por tratarem-se de plantas sem propagação vegetativa, portanto com menos reservas, mesmo subdosagens de glifosato reduziriam o desenvolvimento de Urochloa ruziziensis.…”

“…A implementação desse sistema de consórcio representa uma alternativa de manejo que propicia maior racionalidade na utilização dos recursos de produção, inclusive tempo, além de reduzir a infestação de plantas daninhas (ABBAS et al, 2018;TIMOSSI et al, 2018). A competição por fatores de desenvolvimento entre cultura e forrageira irá ocorrer, com consequente escassez de fatores de desenvolvimento, sendo necessário equilibrar-se as capacidades competitivas das espécies consorciadas com a supressão do desenvolvimento da forrageira com uso de herbicidas (FRANCHINI et al, 2015;SILVA et al, 2016).…”

Uso de subdoses de glyphosate na supressão de espécies forrageiras consorciadas com milho

“…Em trabalho realizado com diferentes espécies do gênero Brachiaria sp., foi comprovado que estas possuem tolerância diferencial ao herbicida glyphosate (Brighenti et al, 2011). Por outro lado, Silva et al (2016), avaliando o uso de glyphosate na supressão de crescimento de espécies em consórcio com o milho, atestaram que doses variando entre 96 e 144 g ha -1 têm potencial para supressão de B. brizantha, em aplicações realizadas sob plantas com 4 perfilhos.…”