Residual herbicides in weed management for glyphosate-resistant soybean in Brazil

Abstract

-In agricultural production systems where the glyphosate-resistant soybean crop (Glycine max) is grown and the practice of crop rotation with alternative herbicides is not adopted, the exclusive and continuous use of glyphosate has led to the occurrence of resistant weed populations that may limit or compromise the benefits of this technology. Thus, the efficacy of weed management programs, including the use of residual herbicides (sulfentrazone, flumioxazin, imazethapyr, diclosulan, chlorimuron and s-metolachlor) applied in preemergence and followed by in-crop postemergence applications of glyphosate (PRE-POST) were compared to glyphosate postemergence only programs -POST. The study was conducted across nine locations during the 2009/2010 and 2010/2011 growing seasons. PRE-POST programs were efficient in the control of Amaranthus viridis, Brachiaria plantaginea, Bidens pilosa, Commelina benghalensis, Eleusine indica, Euphorbia heterophylla and Raphanus raphanistrum, with the level of control being similar when comparing the program with two applications of glyphosate POST. Some PRE-POST programs were not efficient in controlling Cenchrus echinatus, Ipomoea hederifolia and Ipomoea triloba. Sulfentrazone and diclosulam PRE-POST programs improved the control of Ipomoea triloba compared to sequential applications of glyphosate alone. No significant differences in soybean yield were observed between any of the herbicide treatments or study locations. The use of residual herbicides in preemergence followed by glyphosate incrop postemergence provides consistent weed control and reducing early season weed competition. Furthermore, these programs utilize at least two herbicide modes of action for herbicide use diversity, which will be needed to stay ahead of resistance build-up, regardless of when weeds may appear. Keywords:Herbicide resistance management, mode of action, residual herbicides, weed management programs, preemergence, postemergence. Palavras-chave: manejo de resistência a herbicida, modo de ação, herbicidas residuais, programas de manejo de plantas daninhas, pré-emergência, pós-emergência. RESUMO -Em sistemas de produção agrícola onde a cultura da soja tolerante ao glyphosate (Glycine max) está inserida e onde não há a prática de rotação de culturas com herbicidas alternativos, o uso exclusivo e contínuo do glyphosate tem levado ao surgimento de populações de plantas daninhas resistentes, que podem limitar ou comprometer os benefícios dessa tecnologia. Nesse sentido, a eficiência de programas de manejo que envolvem herbicidas residuais (sulfentrazone, flumioxazin, imazethapyr, diclosulam, chlorimuron e s-metolachlor) aplicados na pré-emergência seguidos de glyphosate na pós-emergência da cultura (PRE-POST) foi comparada à de programas com apenas glyphosate na pós-emergência -POST. O estudo constituiu-se de nove experimentos

Efficacy and selectivity of pre-emergent sunflower herbicides under different soil moisture conditions

“…PRE herbicides with residual activity can also improve efficacy of POST acetolactate synthase (ALS)-inhibiting herbicides in controlling weeds in sunflower. PRE herbicides in HT crops are an effective anti-resistant strategy that reduces the risk of herbicide resistance development (Lopes Ovejero et al 2013;Beckie & Hall 2014).…”

Residual Activity of Sulfentrazone Applied to Soybean on Cotton Crop in Succession

“…Sulfentrazone application in pre-emergence did not significantly alter (p<0.05) the assessed variables in soybean up to a dose of 1,200 g ha -1 (Tables 1 and 2). On the other hand, in another study, sulfentrazone application in pre-emergence at a dose of 400 g ha -1 led to injuries in soybean plants at 7 DAA, but no visual symptoms of intoxication were observed at 14 DAA (López-Ovejero et al, 2013). This result may be related to the cultivar.…”

Detection of glyphosate resistance in black nightshade Solanum nigrum from Hunan China

“…Among all reported glyphosate resistant weeds, most of them are belonging to the 'narrow leaf' species from the Gramineae family. At the same time, the broadleaf species are only found from the Comositae and Amaranthaceae families such as Amaranthus palmeri, Biden pilosa, and Conyza canadensis, etc [11][12][13] . S. nigrum is a weed species of great importance in agriculture, and our group has been studying on the S. nigrum populations in recent years.…”