Assessing weeds at risk of evolving glyphosate resistance in Australian sub-tropical glyphosate-resistant cotton systems

Abstract

Glyphosate resistance will have a major impact on current cropping practices in glyphosate-resistant cotton systems. A framework for a risk assessment for weed species and management practices used in cropping systems with glyphosate-resistant cotton will aid decision making for resistance management. We developed this framework and then assessed the biological characteristics of 65 species and management practices from 50 cotton growers. This enabled us to predict the species most likely to evolve resistance, and the situations in which resistance is most likely to occur. Species with the highest resistance risk were Brachiaria eruciformis, Conyza bonariensis, Urochloa panicoides, Chloris virgata, Sonchus oleraceus and Echinochloa colona. The summer fallow and non-irrigated glyphosate-resistant cotton were the highest risk phases in the cropping system. When weed species and management practices were combined, C. bonariensis in summer fallow and other winter crops were at very high risk. S. oleraceus had very high risk in summer and winter fallow, as did C. virgata and E. colona in summer fallow. This study enables growers to identify potential resistance risks in the species present and management practices used on their farm, which will to facilitate a more targeted weed management approach to prevent development of glyphosate resistance.

Herbicide resistance modelling: past, present and future

“…This review focuses on modelling the evolution of herbicide resistance, in contrast to other recent overviews that have taken a different or wider focus, such as modelling the evolution of resistance to pesticides and drugs in general, or modelling weed population dynamics in general . We also focus on models that represent or simulate the dynamic evolutionary and population processes underlying the evolution of resistance, while recognising the value of many other types of modelling, such as more empirical modelling of herbicide risk assessment or economic modelling that does not explicitly represent genetics …”

RIM: Anatomy of a Weed Management Decision Support System for Adaptation and Wider Application

“…Moreover, several such indicators already exist, such as those described in Stanton et al (2008) and in Werth et al (2011) for glyphosate use in Australia.…”

Weed management in cotton (Gossypium hirsutum L.) through weed-crop competition: A review

“…Commelina benghalensis L. is a weed that is difficult to control with glyphosate and becoming predominant in the cotton growing zones of the USA (Webster et al, 2005). Similarly, C. bonariensis is becoming prominent in the Australian cotton growing zones and is hard to control with glyphosate (Werth et al, 2011). In the US cotton growing regions, Ipomoea spp.…”

“…Many A. palmeri populations have rapidly evolved resistance to glyphosate in North America (Culpepper, 2006;Norsworthy et al, 2007;Sosnoskie and Culpepper, 2014;Webster and Sosnoskie, 2010) and it is an issue that many weeds from Amaranthacea family are predominant weeds in the cotton producing zones (Table 1). C. canadensis and C. bonariensis are present in many cotton growing regions and these weeds are difficult to manage with glyphosate (Flessner et al, 2015;Werth et al, 2011). Echinochloa sp.…”

“…Poor weed management in cotton can lead to a significant yield reduction; depending on weed management, yield reductions can range from 10 to 90% (Dogan et al, 2015;Morgan et al, 2001;Oerke, 2006;Robinson, 1976). Rapidly emerging herbicide-resistant weeds further adds to the complexity of cotton weed management (Webster and Sosnoskie, 2010;Werth et al, 2011). A major change that occurred in the cotton farming is the rapid adoption of genetically modified herbicide-tolerant cultivars (GM cultivars), of which glyphosate-tolerant cotton accounts a major proportion (ISAAA, 2015).…”