Trends in the use of pesticides and pesticide residues on Queensland wool

Objective To determine the amounts of organophosphorous and synthetic pyrethroid residues on Queensland wool sampled between 1995 and 1997, and to study ii pesticide use changed during the period. Design Estimated amounts of residues were obtained from a survey of Queensland wool clips, and information on pesticide use was obtained from a trace-back postal survey of flock managers. Procedure Trends in amounts of residues over time were assessed using analysis of variance and simple linear regression models, and changes in pesticide use was assessed using chi(2) tests. Results Significant linear reductions in organophosphorous (P = 0.0012), synthetic pyrethroid (P = 0.0044) and total (P = 0.0002) residues were detected. The proportion of wool growers treating for louse infestation (P = 0.0046) treating twice or more (P = 0.0006) and treating more than 4 months after shearing (P = 0.0001) decreased between 1994 and 1997. However, the proportion of growers who treated for blowfly strike (P = 0.0124) and used insect growth regulator pesticides increased (P < 0.0001). The use of handjetting to apply pesticides for blowfly strike control increased and the use of dips decreased (P < 0.0001). Conclusion Residues of organophosphorous compounds and synthetic pyrethroids reduced in Queensland wool between 1994 and 1997. Although woolgrowers treated for louse infestation less, pesticide use to control blowfly strike increased. The increasing use of insect growth regulators in the industry needs to be monitored.