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Weed management practices in glyphosate-tolerant and conventional cotton fields in Australia

J. A. Werth A B F , C. Preston A , G. N. Roberts C D and I. N. Taylor B E
+ Author Affiliations
- Author Affiliations

A School of Wine and Agriculture, University of Adelaide and CRC for Australian Weed Management, PMB 1, Waite Campus, Glen Osmond, SA 5064, Australia.

B Cotton Catchment Communities Cooperative Research Centre, Locked Bag 1001, Narrabri, NSW 2390, Australia.

C CSIRO Plant Industry, Locked Bag 59, Narrabri, NSW 2390, Australia.

D Current address: ‘Stradbrooke Park’, PO Box 207, Clare, SA 5453, Australia.

E Cotton Research and Developent Corporation, PO Box 282, Narrabri, NSW 2390, Australia.

F Corresponding author: Email:

Australian Journal of Experimental Agriculture 46(9) 1177-1183
Submitted: 17 June 2005  Accepted: 2 November 2005   Published: 4 August 2006


Forty growers in 4 major cotton-growing regions in Australia were surveyed in 2003 to investigate how the adoption of glyphosate-tolerant cotton (Roundup Ready) had influenced herbicide use, weed management techniques, and whether changes to the weed spectrum could be identified. The 10 most common weeds reported on cotton fields were the same in glyphosate-tolerant and conventional fields in this survey. Herbicide use patterns were altered by the adoption of glyphosate-tolerant cotton with up to 6 times more glyphosate usage, but 21% fewer growers applying pre-emergence herbicides in glyphosate-tolerant fields. Other weed control practices such as the use of post-emergence herbicides, inter-row cultivation and hand hoeing were only reduced marginally. However, growers indicated that management practices are likely to change over time, especially with the introduction of enhanced glyphosate tolerance technology (Roundup Ready Flex), and anticipate a 32% decrease in the number of growers using alternative weed management practices. To date, management practices other than glyphosate use have not changed markedly in glyphosate-tolerant cotton indicating a conservative approach by growers adopting this technology and reflecting the narrow window of herbicide application. The range of weed control options still being employed in glyphosate-tolerant cotton would not increase the risk of glyphosate resistance development.

Additional keywords: integrated weed management, resistance, survey, Roundup Ready.


We thank the growers who participated in this survey for their time and willingness to have their farm records examined. Assistance from Greg Constable and Lewis Wilson was also appreciated. This research was funded by the Cooperative Research Centre (CRC) for Australian Weed Management and the Australian Cotton CRC.


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