Glyphosate sustainability in South American cropping systems

Abstract

South America represents about 12% of the global land area, and Brazil roughly corresponds to 47% of that. The major sustainable agricultural system in South America is based on a no-tillage cropping system, which is a worldwide adopted agricultural conservation system. Societal benefits of conservation systems in agriculture include greater use of conservation tillage, which reduces soil erosion and associated loading of pesticides, nutrients and sediments into the environment. However, overreliance on glyphosate and simpler cropping systems has resulted in the selection of tolerant weed species through weed shifts (WSs) and evolution of herbicide-resistant weed (HRW) biotypes to glyphosate. It is a challenge in South America to design herbicide- and non-herbicide-based strategies that effectively delay and/or manage evolution of HRWs and WSs to weeds tolerant to glyphosate in cropping systems based on recurrent glyphosate application, such as those used with glyphosate-resistant soybeans. The objectives of this paper are (i) to provide an overview of some factors that influence WSs and HRWs to glyphosate in South America, especially in Brazil, Argentina and Paraguay soybean cropped areas; (ii) to discuss the viability of using crop rotation and/or cover crops that might be integrated with forage crops in an economically and environmentally sustainable system; and (iii) to summarize the results of a survey of the perceptions of Brazilian farmers to problems with WSs and HRWs to glyphosate, and the level of adoption of good agricultural practices in order to prevent or manage it.

Influence of soil tillage and erosion on the dispersion of glyphosate and aminomethylphosphonic acid in agricultural soils

“…The major sustainable agricultural systems in South America and USA are fundamentally based on a technological package that combines no-till and glyphosate in the cultivation of maize (Aparicio et al, 2013;Cerdeira and Duke, 2006;Christoffoleti et al, 2008.) The no-tillage system (direct drill) is becoming more and more important also in the Austrian agricultural practice, tending to substitute the plough.…”

Glifosato aplicado com diferentes concentrações de uréia ou sulfato de amônio para dessecação de plantas daninhas

“…O glifosato é um herbicida muito útil para a adoção em sistemas de baixo impacto ambiental, em razão de seu amplo espectro de controle e baixa toxicidade a organismos não alvo (Trigo & Cap, 2003;Christoffoleti et al, 2008). Trata-se de herbicida não seletivo, de ação sistêmica, usado no controle de plantas daninhas anuais e perenes e na dessecação de culturas de cobertura (Rodrigues & Almeida, 2005;Timossi et al, Pesq.…”

“…O advento das culturas geneticamente modifi cadas, quanto à tolerância a herbicidas, também tem contribuído sobremaneira para a maior adoção do glifosato (Young et al, 2003); e problemas decorrentes de seu uso repetitivo já foram relatados, entre os quais a seleção de espécies tolerantes ou de biótipos de plantas daninhas resistentes ao produto (Monquero & Christoffoleti, 2003;Christoffoleti et al, 2008). A trapoeraba (Commelina benghalensis L.), por exemplo, tem sido selecionada em áreas com sucessivas aplicações de glifosato, por sua tolerância ao herbicida -entre outras características -, a qual está correlacionada à sua habilidade em metabolizar a molécula a compostos menos tóxicos (Monquero & Christoffoleti, 2003;Monquero et al, 2004).…”

Hairy Fleabane as a Source of Major Insect Pests of Soybean

“…It is annual and has an enormous reproductive capacity and a potential to produce 200,000 seeds per plant, which are easily dispersed by the wind (Moreira et al, 2007). Its control has been doi: 10.1590/S0100-83582016340300001 difficult in recent years due to the selection of resistant populations to glyphosate (Vargas et al, 2007;Lamego and Vidal, 2008), a herbicide widely used to control weeds in soybeans, particularly for glyphosateresistant cultivars (GR) (Young et al, 2003;Christoffoleti et al, 2008).…”