Roundup Ready cotton has been commercially available to Australian cotton growers for five years and has been widely adopted by the industry with approximately 77% of the area planted to Roundup Ready cotton in the 2005/06 season. The next generation of herbicide tolerant cotton varieties; Roundup Ready Flex and Liberty Link, are likely to become commercially available over the next couple of years. These traits will allow the cotton industry to further develop in-crop weed management systems that may rely almost exclusively on the use of one or other of these technologies. The widespread adoption of these technologies is likely to result in a further decrease in the use of residual herbicides, inter-row cultivation and hand-hoeing in cotton fields. Adoption of these systems should reduce crop establishment problems, allow better yields and reduce problems of environmental contamination currently occurring with residual herbicides. However, their use is also likely to further exacerbate problems with species shift, herbicide spray drift and the control of volunteer crop plants, as well as increasing the risk of weeds developing herbicide resistanc