Spray drift definitions

It is essential that the spray drift restraints and other label use instructions as given in the Ag Labelling Code and the spray drift risk assessment manual (SDRAM) are interpreted according to the following definitions of terms.

Agricultural crops

‘Agricultural crops’ means any terrestrial plant species grown commercially for food, fibre, foliage, fuel or medicinal production, with the following exception:

 

  • plants that are not part of a crop under management at the time of pesticide application (eg blackberries or volunteer grain plants that have escaped from a cropped area and become weeds in another area).

Aircraft

An ‘aircraft’ is a fixed-wing or rotary aircraft that applies spray in-flight. This includes unmanned aerial vehicles (UAVs). This excludes application equipment defined as a ‘boom sprayer’ or ‘vertical sprayer’ or when the product is used for any use pattern not requiring a spray drift risk assessment.

Application site

The ‘application site’ refers to the area or field where it is intended for the spray to be applied.

Aquacultural production

‘Aquacultural production’ means commercial production of any aquatic plant or aquatic animal species for food or ornamental purposes. This does not include those which are not part of an area of aquacultural production under management at the time of pesticide application (eg fish that have escaped into natural watercourses).

Boom height

For the purposes of ground boom sprayer, ‘boom height’ is the distance between the top of the ‘target canopy’ and the nozzle tip. If no canopy is present the boom height is the height above the ground. Boom height is only considered as being typical across the application site, not a maximum height. Increases in release height for short periods during application are not considered as being non-compliant with the boom height in a use instruction. These increases are expected and are adequately managed through principles of good agricultural practice.

Boom sprayer

A ‘boom sprayer’ is one that applies spray downward from a ground-based horizontal boom. This excludes application equipment defined as a ‘vertical sprayer’ or ‘aircraft’ or when the product is used for any use pattern not requiring a spray drift risk assessment. This includes nozzles known as boomless jets, which are mounted to a vehicle and used to produce a swath significantly wider than the vehicle itself.

Buffer zone

A ‘buffer zone’ is an area where pesticide application does not occur between the application site and an identified sensitive area which is downwind from the application site. For boom and aerial spraying, a buffer zone is measured from the edge of the sprayer swath closest to the downwind sensitive area; for vertical spraying, a buffer zone is measured from half a row width (ie trees, vines, other plants) outside the application site closest to the downwind sensitive area.

Bystander areas

‘Bystander areas’ are locations where it is reasonably likely that ‘bystanders’ will be exposed to residues deposited on the ground from spray drift on a regular basis and for an extended period of time (ie several hours per day over a period of a month). Examples of these areas include: residential properties, schools, kindergartens, day care facilities, hospitals, aged care facilities, public or private parks or recreational areas, and areas where manual handling of soil or plants is required.

Bystanders

‘Bystanders’ means people not involved in mixing, loading or applying the pesticide and are without the personal protective equipment (PPE) required by the product label.

Contamination

‘Contamination’ means a failure of plant or livestock commodities to comply with the APVMA Maximum Residue Limit Standard.

Droplet size distribution

As defined by ASTM E2798, Standard Test Method for Characterization of Performance of Pesticide Spray Drift Reduction Adjuvants for Ground Application, ‘mathematical or graphical representation of droplet sizes of a given spray frequently shown as a volume fraction, number fraction, or cumulative fraction distributions.’


Note that only the volume fraction (or cumulative volume fraction) is relevant for this manual.

Dilute water rate

For ‘vertical sprayers’, ‘dilute water rate’ means the amount of water applied per hectare to reach the point of run-off (ie where the target plant is thoroughly wet).

Hazardous surface temperature inversions

‘Surface temperature inversions’ occur when air temperature increases with height from the ground surface, which is the opposite of what normally happens (i.e. the temperature profile is 'inverted'). This results in a layer of cool, still air being trapped below warmer air. In surface temperature inversion conditions airborne pesticides can concentrate near the surface and unpredictable winds can move droplets away from the target area. The direction and distance which the droplets will move becomes unpredictable.
A surface temperature inversion is likely to be present if:

 

  • mist, fog, dew or a frost have occurred
  • smoke or dust hangs in the air and moves sideways, just above the ground surface
  • cumulus clouds that have built up during the day collapse towards evening
  • wind speed is constantly less than 11 km/hr in the evening and overnight
  • cool off-slope breezes develop during the evening and overnight
  • distant sounds become clearer and easier to hear
  • aromas become more distinct during the evening than during the day.

When application occurs in an area not covered by recognised inversion monitoring weather stations, all the surface temperature inversion conditions are regarded as hazardous and the above definition will always apply.

Landscaped gardens

‘Landscaped gardens’ means any terrestrial plant species grown for ornamental purposes on private or public land, or for domestic food production on private land, with the following exceptions:

 

  • species that are declared noxious or invasive to the area of application by local, state or commonwealth legislation
  • plants that are not part of a garden under management at the time of pesticide application (eg flowering plants that have escaped from a home garden and have become weeds in another area).

Livestock areas

‘Livestock areas’ are those where livestock are grazing. ‘Buffer zones’ for ‘livestock areas’ have been established to protect international trade. These buffer zones are based on the Maximum Residue Limit (MRL) Standards of significant export markets for livestock commodities.

Native vegetation

‘Native vegetation’ means any terrestrial plant species native to Australia as defined under local, state or commonwealth legislation with the following exceptions:

 

  • species that are declared noxious or invasive to the area of application by local, state or commonwealth legislation
  • plants that the chemical user, or the person the chemical user is applying agricultural chemical product/s on behalf of, is legally allowed to remove under local, state or commonwealth legislation.

‘Buffer zones’ for the purpose of ‘native vegetation’ may also be used as the basis for the protection of ‘agricultural crops’ and ‘landscaped gardens’. However, ‘buffer zones’ for ‘native vegetation’ are based on survival at a population or ecosystem level and they may not be sufficient if yield loss or replacement cost is the issue.

Natural aquatic areas

‘Natural aquatic areas’ are where a ‘watercourse’ (as defined by the Commonwealth Water Act 2007) is present, with the following exceptions:

 

  • artificial ‘watercourses’ used exclusively for agricultural or ornamental purposes, such as irrigation channels, flood irrigation areas, farm dams, ornamental ponds, golf course dams and those used for aquacultural production
  • ‘watercourses’ that are dry at the time of pesticide application
  • ‘watercourses’ that are commonly identified as ‘puddles’.

‘Buffer zones’ established for the purpose of the ‘natural aquatic area’ may also be used as the basis for the protection of ‘aquacultural production’ but as the buffer zones for ‘natural aquatic areas’ are based on survival at a population or ecosystem level, they may not be sufficient if yield loss or replacement cost within an aquaculture operation is the issue.

Pollinator areas

’Pollinator areas’ means managed bee hives. This only applies when the manager of those bee hives has provided notification regarding their location to the chemical user, or the person the chemical user is applying agricultural chemical product/s on behalf of, at least 48 hours prior to application of the agricultural chemical product/s. While notification can be made directly (in writing or verbally), the use of the BeeConnected website or smartphone app is acceptable and recommended.

Release height

For the purposes of aircraft, ‘release height’ is the distance between the top of the ‘target canopy’ and the nozzles on the aircraft. Pilot safety is paramount, so the release height is only considered as being typical across the application site, not a maximum flying height. Increases in release height for short periods during application to avoid obstacles, or turn at the end of runs, are not considered as being non-compliant with the release height in a use instruction. These increases are expected and are adequately managed through principles of good agricultural practice by the aerial agricultural industry.

Relevant output of the spray drift management tool

For the purposes of use instructions, a ‘relevant output of the spray drift management tool’ refers to the output from the spray drift management tool following the input of information relevant to the proposed application of a specific product (or products). The specific product may be identified by the APVMA approval number printed on the product label or the product name recorded on the APVMA register.

Rotor diameter

Diameter the rotating blades of a helicopter which generates lift.

Sensitive areas

For the purpose of spray drift management, five different type of sensitive areas are considered in establishing relevant buffer zones. These are ‘bystander areas’, ‘natural aquatic areas’, ‘pollinator areas’, ‘vegetation areas’ and ‘livestock areas’.

Spray cloud

‘Spray cloud’ means the volume of air that is directly adjacent to operating application equipment which contains large numbers of spray droplets in close proximity to each other. The area which the spray cloud covers will vary between types of application equipment and use practices, but is generally defined as the cloud of droplets that is visible by the naked eye shortly after being released into the atmosphere and excludes isolated droplets that are carried downwind from the application area by the wind.

Spray drift

Spray drift is defined by the APVMA as the movement of spray droplets of a pesticide outside of the application site during, or shortly after, application. It does not encompass off-target movement of a pesticide caused by runoff, volatilisation, erosion, or any other mechanism that occurs after spray droplets reach their intended target.

Spray droplet size category

The characteristics of spray droplets produced by a certain nozzle operating at a certain pressure are described in several standards. Specifically, these standards are used by the APVMA for application by ‘boom sprayer’ or ‘aircraft’ only (ie they are not currently relevant for a ‘vertical sprayer’) and describe the following droplet size categories:

 

  • FINE (F)
  • MEDIUM (M)
  • COARSE (C)
  • VERY COARSE (VC)
  • EXTREMELY COARSE (XC)
  • ULTRA COARSE (UC).

Standards also may refer to VERY FINE (VF) or smaller spray droplet sizes but because they pose significant spray drift risk potential, these categories will only be assessed in rare circumstances, based on the submission of spray drift data rather than standard assumptions.


Different nozzle standards are used because no undisputed international standard currently exists. Nozzle manufacturers commonly rely on the standard, which is used in the jurisdiction in which they are based.


The APVMA currently recognises the following standards for the classification of nozzles used on a ‘boom sprayer’:

 

  • American Society of Agricultural and Biological Engineers (ASABE)
    • ANSI/ASAE S572.1 MAR2009: Spray Nozzle Classification by Droplet Spectra
    • ANSI/ASAE S572.2 JUL2018: Spray Nozzle Classification by Droplet Spectra
  • ISO 25358: Crop protection equipment—Droplet-size spectra from atomizers—Measurement and classification.

ASABE S641, Droplet Size Classification of Aerial Application Nozzles, came into effect in May 2018 and the APVMA guidelines may in the future be updated to comply with ASABE S641 for aerial applications.

 

Droplet size categories are currently based on ASAE S572.2 and categories from non-recognised standards will not be used unless sufficient information is provided with an application to enable custom droplet size distributions to be established or the APVMA recognises the standard.

Surface temperature inversions

See ‘Hazardous surface temperature inversions’.

Target canopy

‘Target canopy’ refers to vegetation within the ‘application site’. The ‘target canopy’ can refer to the crop, weeds or any other vegetation within the target area, whichever is the highest.

Unacceptable impact

For the purposes of native vegetation, ‘unacceptable impact’ means a loss of native vegetation that has an impact at a population or ecosystem level. For example, damage to leaves on a small percentage of plants in an area that does not cause a change in the diversity of plants in that area is not an ‘unacceptable impact’ but damage that causes a species of plant in an area to be replaced by another species is an ‘unacceptable impact’. However, it is important to note that this ultimately depends on relevant local, state or commonwealth legislation, which varies between jurisdictions.


For the purposes of ‘agricultural crops’, ‘landscaped gardens’ or ‘aquacultural production’, unacceptable impact will be determined by the policies of the relevant Control-of-Use jurisdiction.

Vegetation areas

‘Vegetation areas’ are where ‘native vegetation’, ‘agricultural crops’ or ‘landscaped gardens’ are present. It does not include vegetation that has been planted explicitly for purpose of a drift buffer.

Vertical sprayer

A ‘vertical sprayer’ is one that applies spray in a direction other than directly towards the ground. This excludes application equipment defined as a ‘boom sprayer’ or ‘aircraft’ or when the product is used for any use pattern not requiring a spray drift risk assessment.

Watercourse

For the purpose of ‘natural aquatic areas’, the current definition of ‘watercourse’ under the Commonwealth Water Act 2007 is a river, creek or other natural watercourse (whether modified or not) in which water is contained or flows (whether permanently or from time to time); and includes:

 

  • a dam or reservoir that collects water flowing in a watercourse
  • a lake or ‘wetland’ through which water flows
  • a channel into which the water of a watercourse has been diverted
  • part of a watercourse
  • an estuary through which water flows.

A ‘wetland’ is an area of land where water covers the soil—all year or just at certain times of the year. They include:

 

  • swamps, marshes
  • billabongs, lakes, lagoons
  • saltmarshes, mudflats
  • mangroves, coral reefs
  • bogs, fens, and peatlands.

A ‘wetland’ may be natural or artificial and its water may be static or flowing, fresh, brackish or saline.

Wind speed

The average wind speed at the application site during the time of application must not exceed the maximum given on the product label. The maximum wind speed (gusts) should not be more than one-third of the average wind speed above the average wind speed.


Wind speed should be measured two metres above the ground at the application site. The point where the wind speed is measure should be representative of the application area and should be free of obstructions that may impact the measurement.

Wing span

The maximum extent across the wings of an aircraft measured from tip to tip.

 

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