The weed management costs incurred by Australian cotton growers represent a significant and often under estimated loss to cotton cropping gross margins. Although there are likely to be a number of weeds present in cotton cropping fields at any one time, some species are more problematic than others' For example, weeds in the family Malvaceae (those related to cotton) are causing increasing problems in many areas, in particular bladder ketmia (Hibiscus trionum), Anoda weed (Anoda cristata) and velvetleaf (Abutilon theophrasti). This paper examines the costs of weed control between fields with and without bladder ketmia, anoda weed and velvetleaf