Spray drift and how to prevent it

There are things you can do to reduce the risk of spray drift.

Preventing spray drift is an essential aspect of using agricultural chemicals responsibly. Spray drift has a number of consequences, including:

• damage to non-target vegetation and crops or non-target organisms
• contamination of animals, agricultural and animal produce and of non-target areas
• human health hazards
• environmental contamination.

Spray drift may also impact on the owner of the crop that has been sprayed, due to:

• monetary loss because the chemical is not placed on the target area
• poor pest control and subsequent crop loss.

What is spray drift?

Spray drift consists of any non-target pesticide or herbicide loss as a result of either aerial or ground application. It occurs when chemical droplets/particles or vapour remain in the air after application and move to non-target areas.

This can occur in a number of ways, either separately or in combination:

• Direct wind drift occurs when chemical droplets are carried on the wind, and usually occurs as a result of small spray droplets, strong winds and/or spray being released too far above the ground.
• Thermal drift occurs as a result of unstable meteorological conditions. Chemical droplets are carried on thermal eddies and deposited some distance from the target site.
• Inversion drift occurs when droplets remain on top or suspended in an inversion layer and are deposited when the inversion breaks. This results in irregular deposition at some distance from the release point.
• Vapour drift occurs when pesticide or herbicide is sprayed onto the target, but then passes off as vapour and moves downwind of the point of application. Some herbicides are volatile and particularly prone to this, and can severely damage plants over a wide area. To counteract this situation three designated Hazardous Areas in mixed cropping areas have been declared under Queensland Government legislation to restrict the use of certain volatile herbicides in these areas.

How to prevent spray drift

For effective application of agricultural chemicals and to prevent spray drift, the following steps should be taken:

• Maintain control of all spray operations. Stop spraying, or stop the contractor spraying if the conditions are not right.
• Read the chemical product label and follow the instructions accurately.
• If possible, choose a product that is non-volatile.
• Identify sensitive crops and areas around the area where you intend to spray, and let the spray operator know about these areas.
• Discuss your spray plans with your neighbours and contractors.
• If possible maintain a buffer zone between areas of application and areas where there is a risk of damage from spray drift.
• Select and check equipment carefully.
• Select equipment (applicators and nozzles) that will give you the correct droplet size range to minimise drift and maximise efficiency. Smaller droplets are more likely to drift.
• Minimise the height at which the spray is released. If spray is being applied aerially, make sure that it is released only when the aircraft has levelled out above the crop.
• Calibrate the equipment correctly.
• Spray only in favourable weather conditions.
• Ideal wind speeds are 3-15 km/h.
• During spraying, wind should be blowing steadily. Light and variable or gusty winds make it difficult to predict where spray will go.
• Spraying should not be carried out under calm or still conditions. Under calm conditions, droplets are more likely to remain suspended in the air.
• Ideally, wind should be blowing away from susceptible crops.
• Spray with a cross wind, i.e. at right angles to the direction the sprayer is travelling.
• Avoid spraying in temperatures near or above 28°C - the cooler the temperature the better. Spraying during high temperature conditions can result in pesticide evaporating or turning into vapour. Higher ground temperatures establish air currents, which lift spray mist and carry them so that they spread over a wide area.
• Spray when humidity is high, i.e. greater than 45%. This is particularly important when the pesticide is dissolved in water, as low humidity is often associated with high temperatures and thus high evaporation.
• Do not spray when inversion conditions exist.

More detailed advice on spray drift reduction strategies can be found by following the links at the bottom of this page to Spray right - reduce drift and the 'Agricultural chemical users' manual'.

What to do if spray drift occurs

Spray drift and agricultural damage

If you allege that you have suffered loss or damage to crops or stock caused by spray drift, you may notify the Department of Primary Industries and Fisheries (DPI&F) of your loss or damage by contacting the business information centre.

DPI&F focuses on the operator or user alleged to have caused the damage when investigating allegations of agricultural chemical damage to crops or stock notified to the department. All reasonable allegations where a named operator has been provided are investigated by inspectors who look for reliable evidence that the operator may have breached provisions of Queensland's agricultural and veterinary chemical control of use legislation (namely the Agricultural Chemicals Distribution Control Act 1966 (ACDC Act) and the Chemical Usage (Agricultural and Veterinary) Control Act 1988 (Chemical Use Act)). The matter cannot be fully investigated, however, if this reliable evidence is absent.

In the past, DPI&F investigated most notifications of complaints received via a Form 16 with a view to establishing the possible cause of the alleged damage and issuing a statement to the complainant setting out these possible causes. However, this service ceased in November 2000.

DPI&F does not offer compensation for loss of or damage to crops or stock caused by agricultural chemicals. Any civil legal action in relation to spray damage must be undertaken privately.

Spray drift and human health

For information on suspected risk to human health caused by spray drift (including spray on roofs of houses and other buildings, and water tanks), contact your nearest Workplace Health and Safety office, telephone (07) 3872 0529 or visit the Workplace Health and Safety website by following the link at the bottom of this page.

Spray drift and the environment

To report environmental damage believed to be caused by spray drift, contact the Environmental Protection Agency on telephone 1300 130 372 or visit their website.

Further information

• DPI&F Business Information Centre
• Spray drift fact sheet - Grains Research and Development Corporation
• Licensing and permits
• Agricultural Chemical Users' Manual
• Workplace health and safety
• Environmental Protection Agency
• Report an adverse chemical experience