Horticulture risk survey - spray drift (AH11033)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Hort Innovation (which was then Horticulture Australia Limited) commissioned a project to ascertain the status in 2012 of spray drift issues as they related to its diverse crops. This project involved Dr Hewitt and other staff from The University of Queensland surveying attitudes, training and incidents relating to real or perceived spray drift as well as associated training, risk assessment and drift management. The significance of this for the industry was that it helped set a baseline for spraying in 2012 against which future activities related to spray application technology and drift management could be compared. It also put spray drift into perspective by different factors such as crop type, region, local conditions and spraying practices. It helped define issues that could improve training and helped assess whether risk assessment modeling was appropriate.

The survey and audit involved several hundred participants from all major stakeholder groups from government and industry with the following main findings by stakeholder group.

At the federal government level, only a dozen or less annual spray drift incidents in horticulture were documented and risk assessment involved a strong reliance on spray drift exposure modeling using overseas data and models which were not applicable to most horticultural spraying in Australia at the time. At the state level, up to 25 reported incidents per year per state were horticulture linked with approximately 25 per cent being for complaints of human health and 25 per cent for crop damage complaints (often damage to horticultural crops from herbicide applications to other crops), and 75 per cent of those from ground application systems. However, very few were found to be substantive and the proportion of spray events generating spray drift damage was less than 0.01 per cent.

A key issue that needed to be addressed in many areas was land use planning because urban encroachment into rural areas could have impacted on spraying activities, even if only through perceived risk of chemical exposure and complaints of nuisance from noise and machinery.

Spray drift could usually be managed through education/training, technologies and appropriate regulations. Education and training courses could benefit from up-to-date information on spray application techniques and drift management strategies. Some new technologies and adjuvants may have been suited to Australian applications if verified. The risk assessment tools used at the time comprising the AgDRIFT spray drift model and its deposition curves were not considered appropriate to Australian horticulture because the data underlying the model were from spraying systems used in the USA over two decades prior to this report's publication. The project also revealed inconsistencies in the reporting of spray drift. It was recommended that education, technology evaluation and modeling issues be addressed by a consortium of stakeholders because many groups were involved and affected by such activities. The National Working Party on Pesticide Application provides one possible framework for addressing these issues in the future.

The survey involved numerous industry participants so a logical application of the project findings for industry was in helping inform them of the most up-to-date practices and best practices for spraying in horticulture.