How to translate text using browser tools
29 October 2013 Changes in weed species since the introduction of glyphosate-resistant cotton
Jeff Werth, Luke Boucher, David Thornby, Steve Walker, Graham Charles
Author Affiliations +

Weed management practices in cotton systems that were based on frequent cultivation, residual herbicides, and some post-emergent herbicides have changed. The ability to use glyphosate as a knockdown before planting, in shielded sprayers, and now over-the-top in glyphosate-tolerant cotton has seen a significant reduction in the use of residual herbicides and cultivation. Glyphosate is now the dominant herbicide in both crop and fallow. This reliance increases the risk of shifts to glyphosate-tolerant species and the evolution of glyphosate-resistant weeds.

Four surveys were undertaken in the 2008–09 and 2010–11 seasons. Surveys were conducted at the start of the summer cropping season (November–December) and at the end of the same season (March–April). Fifty fields previously surveyed in irrigated and non-irrigated cotton systems were re-surveyed.

A major species shift towards Conyza bonariensis was observed. There was also a minor increase in the prevalence of Sonchus oleraceus. Several species were still present at the end of the season, indicating either poor control and/or late-season germinations. These included C. bonariensis, S. oleraceus, Hibiscus verdcourtii and Hibiscus tridactylites, Echinochloa colona, Convolvulus sp., Ipomea lonchophylla, Chamaesyce drummondii, Cullen sp., Amaranthus macrocarpus, and Chloris virgata. These species, with the exception of E. colona, H. verdcourtii, and H. tridactylites, have tolerance to glyphosate and therefore are likely candidates to either remain or increase in dominance in a glyphosate-based system.

© CSIRO 2013
Jeff Werth, Luke Boucher, David Thornby, Steve Walker, and Graham Charles "Changes in weed species since the introduction of glyphosate-resistant cotton," Crop and Pasture Science 64(8), 791-798, (29 October 2013).
Received: 10 May 2013; Accepted: 1 August 2013; Published: 29 October 2013
Glyphosate resistance
Glyphosate-resistant cotton
species shift
weed survey
Get copyright permission
Back to Top