Abstract:
A survey form asking the cost of weed control, the major weed problems and the herbicides used was sent to fifty two cotton growers from the seven major cotton areas of New South Wales. On average, weed control costs the cotton grower $187 /ha annually. The major components of this cost are $76/ha for herbicides in cotton and $67 /ha for hand chipping. The most important cotton weeds are noogoora burr, bathurst burr, nutgrass, Chinese lantern and peach vine. Although these weeds are problems on a large proportion of the cotton growing area, repeated use of herbicides, cultivation and chipping are reducing their importance. However, nutgass, which is a major weed problem on 15% of the cotton area, is escaping the weed management practices currently used and is rapidly spreading in many fields. Brown beetle grass is an important weed on irrigation channels and is not controlled by the registered herbicides. Trifluralin, diuron and fluometuron herbicides are used in cotton by over 60% of cotton growers. Glyphosate is used by 59% of growers in fallows before cocton, and atrazine, diuron and glyphosate are used by over 60% of growers to control weeds on irrigation channels. Generally cotton growers are dissatisfied with the high cost of weed control, and the ineffectiveness of control of problem weeds such as nutgrass. Growers recommended chat research into nutgrass control should be given top priority.
