Since1988, CRDC has funded a series of projects focussing on the management of problem weeds (nutgrass, polymeria takcall, cowvine, budda pea, lippia and others) and weed management systems for the cotton industry. The research included work on transgenic, herbicide tolerant cotton (Roundup Ready, Oxygene,

Liberty Link and 2,4-D tolerant cotton), noogoora and thornapple competition, herbicides for use with pigeon peas, and monitoring weed management systems.

Nevertheless, weeds continue to cause significant problems for the cotton industry, and the cost of weed control increases year by year. Four of the key weed problems in cotton are nutgrass, cowvine, bellvine, and polymeria takcall. While considerable research has been undertaken on nutgrass, there are still considerable gaps in the knowledge of this weed and its management. Even less is known of the management options for cowvine, bellvine and polymeria takcall in irrigated cotton.

Problems with weed control are being exacerbated by changes in the farming system, with trends towards reduced cultivation, reduced chipping and stubble retention. These changes are placing increasing pressure on the use of herbicidcs, and as a consequence, a group of problem weeds that are largely tolerant of the

commonly used herbicides has been selected out. The increase in residual herbicide use also has had flow-on environmental impacts both on and off the farm.

In order to address this situation, ACGRA has requested that the weeds team put all available information together into a WEEDpak format during the next year. Much of the data collected in DAN 124C and previous projects will form an important part of WEEDpak. This will provide a valuable resource to cotton growers and will also allow future research and extension priorities to be more readily identified.