In a two season study, results from large scale field trials, supported by laboratory bioefficacy experiments showed that the adoption of Large Droplet Placement (LDP) techniques for the aerial application of insecticides, (endosulfan and chlorpyrifos) did not have a significant effect in reducing the biological efficacy of the pesticides when compared to aerial Ultra Low Volume (ULV) and ground rig application.

Drift studies undertaken simultaneous with this project by the Centre for Pesticide Application & Safety, (CRDC UQ 27C, Optimisation of large droplet placement (LDP) technology for the aerial application of insecticides in cotton) showed that the use of LDP application techniques reduced the downwind drift ten to fifteen times, compared to ULV applications. This finding shows that LDP techniques can be adopted to reduce the potential for spray drift resulting from the aerial application of pesticides whilst maintaining the effectiveness of certain contact insecticides on heliothis mortality.The results from this study will have a significant effect upon reducing the potential for spray drift resulting from the use of insecticide in the Australian cotton industry. By showing that the efficacy of insecticides was not compromised with the adoption of low spray drift aerial application techniques, the use of LPD technology in BMP can be extended and used with greater confidence. For the CRDC it will increase the Corporations capacity to support be more sustainable and profitable cotton industry by providing significant benefits. Based upon these data and subsequent modelling undertaken by CPAS, the National Registration Authority (now the Australian Pesticides and Veterinary Medicines Authority, APVMA) developed the 1999/2000 endosulfan cotton label in response to the detection of endosulfan residues in beef cattle during the 98/99 cotton season. The APVMA consequently focussed solely upon reducing off target contamination and aerial transport of droplets, not the biological efficacy of the product.