Managing spray drift
'Spray drift' is the airborne movement of agricultural chemicals as droplets, particles or vapour and is a major issue in some regions of Victoria.
Off-target spray drift does not only relate to herbicides damaging susceptible plants outside the target area as it can also cause unacceptable chemical residues that impact upon domestic and international market trade.
If you suspect spray drift has occurred on your property, please report the issue. As an agricultural chemical user, you have a legal obligation to ensure that the chemicals you apply stay within the target area.
Under the Agricultural and Veterinary Chemicals (Control of Use) Act 1992, it is an offence to undertake agricultural spraying which:
- injures any plants or stock outside of the target area
- injures any land outside the target area so that growing plants, or keeping stock on that land would result in contamination
- is likely to contaminate any agricultural produce derived from plants or stock outside the target area.
Tips to minimise off-target spray drift
A combination of factors can contribute to spray drift, including the volatility of the chemical, weather conditions, equipment and droplet size.
Listed are some handy tips to help chemical users minimise off-target spray drift:
- Always read and follow the product label directions, including any restrictions. Many labels now detail weather conditions, droplet size, equipment and spray drift restraints and mandatory buffer zones to help users manage drift.
- Before you start, check that the weather conditions are suitable for spraying (wind speeds between 3 to 15km per hour blowing away from sensitive crops and areas, Delta T between 2 and 8, no inversion layer present). If the weather is unstable or unpredictable, don't spray. Continue to monitor weather conditions while spraying and stop spraying if it turns unfavourable.
- Choose a chemical formulation that is less likely to drift off-target (use amine formulations of 2,4-D instead of high volatile ester formulations).
- Check for susceptible plants, animals and areas (streams, bee hives) close to the target area and put strategies in place to protect them from drift. Use a buffer zone or leave an unsprayed buffer next to a susceptible crop.
- Discuss your spray plans with neighbouring properties, particularly if you plan to spray near a sensitive crop or area. This provides them with the opportunity to implement protective measures on their property if needed and can help avoid complaints later.
- Ensure your equipment is set up and calibrated correctly.
- Use a nozzle or sprayer setting that produces the largest possible droplet size (coarsest spray quality) without compromising the efficacy of the chemical. Larger droplets are less likely to drift.
Spray drift guidelines
Buffer zones and vegetative barriers
Buffer zones and vegetative barriers are valuable tools that can be used to reduce the potential for spray drift when applying agricultural chemicals.Read more
Living in harmony: pesticides and bees
Information on managing risks associated with agricultural spraying near apiary sites.Read more
Recognising surface temperature inversions
It is unsafe to spray when conditions favour surface temperature inversions, due to the potential for spray drift. Learn how to identify weather conditions associated with surface temperature inversions.Read more
Spray drift restraints and mandatory buffer zones
This page explains some of the operating principles in relation to spray drift risk such as how to correctly apply mandatory buffer zone labels.Read more
Guide to estimating wind speed
This guide is not intended as a substitute for electronic hand held weather meters, which are available from spray equipment suppliers.Read more
Volatile vapour drift risk
Learn about the risks associated with volatile vapour production by ester formulations of phenoxy herbicides.Read more
- Spray drift risk assessment manual — The Australian Pesticides and Veterinary Medicines Authority (APVMA) published the 'Spray drift risk assessment manual’ which mandates specific label instructions based on potential impacts of spray drift.
- GRDC surface temperature inversions and spraying — A factsheet produced by the Grains Research Development Council (GRDC) on the influence of surface temperature inversions on spray operations.