Efficacy of Control of Glyphosate-Tolerant Species of the Rubiaceae Family Through Double-Knockdown Applications

• Autor(a) principal: KALSING,A.
• Data de Publicação: 2020
• Outros Autores: ROSSI,C.V.S., LUCIO,F.R., MINOZZI,G.B., GONÇALVES,F.P., VALERIANO,R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Planta daninha (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582020000100223
• topic: 2,4-dichlorophenoxyacetic acid; ammonium glufosinate; Spermacoce latifolia; Spermacoce verticillata; Richardia brasiliensis

ABSTRACT: Spermacoce latifolia, S. verticillata, and Richardia brasiliensis (family Rubiaceae, tribe Spermacoceae) are glyphosate-tolerant weeds in the soybean producing areas of Brazil. The weed shifts to glyphosate-tolerant weeds across soybean-producing areas has shown the need for adoption of practices that conserve the efficacy of glyphosate. This study evaluated the effect of single- and double-knockdown herbicide applications on the control of S. latifolia, S. verticillata, and R. brasiliensis prior to soybean sowing. Trials were designed as a randomized block and treatments were arranged as a factorial. Factor A was three systemic herbicide treatments 10 days before sowing (DBS), while Factor B was three contact herbicide treatments applied 0 DBS (“sow and apply”). The single- and double-knockdown applications were followed by post-emergence applications of glyphosate or 2,4-D + glyphosate when the crop reached three leaves. The efficacy of control of each weed species was visually evaluated 14 days after sowing (DAS), as well as 0 and 28 days after post-emergence application (DAA). The double-knockdown applications generally provided higher levels of control for the target weeds of the Rubiaceae family than the single-knockdown applications. Glyphosate + 2,4-D, glyphosate + 2,4-D + diclosulam or glyphosate + [halauxifen-methyl + diclosulam] followed by glufosinate or paraquat achieved at least 90% of control of S. latifolia and R. brasiliensis, but did not control S. verticillata (<80%). Glufosinate at 457 g a.i. ha-1 was equivalent to paraquat at 400 g a.i. ha-1 as a contact herbicide in the double-knockdown applications, especially on the first assessment dates.