Weed Control from Herbicide Combinations with Glyphosate¹

Abstract

Greenhouse studies were initiated to evaluate glyphosate alone and tank-mixed with acifluorfen, CGA 277476, chlorimuron, cloransulam-methyl, fomesafen, imazaquin, or pyrithiobac on seedling johnsongrass, broadleaf signalgrass, pitted morningglory, and hemp sesbania. Johnsongrass and broadleaf signalgrass control by glyphosate was not affected by the selective herbicides applied in mixtures. Pitted morningglory control by glyphosate ranged from 0% with 280 g ai/ha to 67% with 840 g/ha. There was an additive effect when selective herbicides were added to 280 g/ha glyphosate 2 wk after treatment (WAT). When acifluorfen was added to 560 g/ha glyphosate, pitted morningglory control 2 WAT increased to 100% compared with 55% with glyphosate alone. Similarly, the addition of fomesafen or acifluorfen to 840 g/ha glyphosate controlled pitted morningglory 2 WAT by 90 and 98%, respectively, compared with 67% with glyphosate alone. Only tank mixtures of acifluorfen, CGA 277476, or fomesafen, and 840 g/ha glyphosate reduced fresh weight compared with glyphosate alone 4 WAT. Acifluorfen, CGA 277476, and fomesafen controlled pitted morningglory by 85 to 100% when added to 1,120 g/ha glyphosate. Both acifluorfen and fomesafen effectively controlled hemp sesbania without the addition of glyphosate 2 WAT. Chlorimuron and pyrithiobac added to 1,120 g/ha glyphosate increased hemp sesbania control to 88 and 99%, respectively, compared with 45% with glyphosate alone 2 WAT. CGA 277476, cloransulam-methyl, imazaquin, and pyrithiobac were antagonistic to hemp sesbania fresh weight reduction when compared with the expected response, but fresh weights were still reduced more than with the same rate of glyphosate alone.

Desempenho agronômico do sorgo em função de doses e épocas de aplicação do herbicida 2,4-D

“…Apresenta elevado potencial de controle em dicotiledô-neas, sendo recomendado para aplicação em pós-emergência na cultura do sorgo (Shaw & Arnold, 2002). Todavia, como já foi verificado em alguns trabalhos (Penckowski et al, 2003;Farinelli et al, 2005;Pacheco et al, 2007) a respeito da sua seletividade a algumas gramí-neas, os resultados são divergentes quanto ao efeito da aplicação desse herbicida.…”

Eficiência técnica e retorno econômico do manejo de buva resistente ao glyphosate em pré-emergência da soja

“…These results support the low control levels obtained on day 14 DAA in the association of glyphosate with chlorimuron-ethyl and flumioxazin (Moreira et al, 2010). The increase in controlling resistant hairy fleabane with the association of 2,4-D is due to the synergism with glyphosate, which helps the absorption and translocation (Waggoner et al, 2011;Takano et al, 2013), contrasting the possible antagonistic effects of the mixture glyphosate with chlorimuron-ethyl and flumioxazin over morning glory, where there was control reduction up to 30% Arnold, 2002). These results support the importance of 2,4-D associated to glyphosate, in order to improve the control of glyphosate-resistant hairy fleabane (Werth et al, 2010;Lamego et al, 2013).…”

Tolerância do cultivar de milheto ADR-300 ao herbicida atrazine

“…Além disso, a disponibilidade de herbicidas seletivos é limitada. Mesmo assim, o controle de espécies latifoliadas tem se mostrado seguro com utilização dos herbicidas 2,4 D (FARINELLI et al, 2005;PACHECO et al, 2007;SHAW;ARNOLD, 2002) e carfentrazona (LYON et al, 2007).…”