PESTICIDE USE AND RESIDUES ON QUEENSLAND WOOL

Objective To determine practices for control of rouse infestation and blowfly strike in Queensland sheep flocks that are associated with org anophosphorous and synthetic pyrethroid residues on wool. Design infor mation on residues was obtained from a survey of Queensland wool clips . Information on pesticide use was obtained from a trace-back postal s urvey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confoundin g by flock location.Procedure Between 1995 and 1997 Queensland wool cl ips were randomly sampled. Samples were tested for the presence and am ount (mg per kg of greasy wool) of organophosphorous and synthetic pyr ethroid pesticides. A questionnaire seeking information on flock chara cteristics and pesticide use was sent to the manager of each flock fro m which a wool sample was tested. Results The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of woo l samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount. Conclusion Most Queens land wool clips have acceptable amounts of residues after the use of O P and SP pesticides, but wool growers can further reduce residues by e ffectively controlling louse infestation with pesticide applications e arly after shearing and the use of non-chemical methods of ectoparasit e control.