The operators' toolbox just got bigger

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New tools for assessing the impact of tank mix, nozzle type and operating parameters on sprayer output are now available to help operators better manage their spray jobs

Screenshot of The Australian Spray Performance Calculator

The Australian Spray Performance Calculator main screen for data input: having access to a tool that can provide coverage information, droplet size data and drift potential specific to the nozzle, tank mix and operating parameters is a leap forward for spray applicators.

SOURCE:  University of Queensland

The choice of nozzle, spray pressure and tank mix composition, including active ingredient and adjuvants, underpins the performance of pesticide spray in terms of cover and spray drift.

In general, the coarser the spray, the lower its drift potential but also the lower the potential coverage on many target surfaces, plants and pests.

Increasing the water volume rate can help boost droplet numbers, but it can still be a challenge to get the right balance between spray coverage and reduced drift in the face of so many variables.

Adjuvant effects are often not particularly intuitive – some adjuvants will increase the number of fine droplets in a spray, while other products may reduce them.

To make things more complicated, different nozzles can have different results and variations can also occur between the outputs from different orifice sizes of the same type of nozzle.

As a part of GRDC-funded projects, University of Queensland (UQ) researchers have measured the performance of more than 1000 combinations of nozzle, pressure and tank mix that cover many Australian grain crop spraying scenarios and have assembled this data into the new Australian Spray Performance Calculator.

This tool has been developed to provide reliable information to take some of the guesswork out of spray performance and help operators improve their drift-management strategies.

Some of the data used to develop the Australian Spray Performance Calculator has also been supplied to the Australian Pesticides and Veterinary Medicines Authority for inclusion in tools that may be approved for use in calculating modified downwind buffer distances as a part of proposed label changes.

The Australian Spray Performance Calculator is able to show many of the key performances of a spray in relative terms:

  • potential coverage in number of droplets per square centimetre;
  • areas covered on the target after droplets have deposited;
  • spray quality, in terms of droplet size classification; and
  • spray-drift potential, indicated as percentage of fines produced.

There will also be other features to provide additional information about spray output, supported by images of what spray deposits may look like on collectors such as water-sensitive paper.

The new tool is available as a spreadsheet (supported by a regularly updated database of information) that can be run on any computer and smartphones or tablets equipped with an Excel reader.

Users can select from a list of drop-down options to enter all of the parameters about their spray, including:

  • nozzle type: the nozzle types and orifice sizes cover 10 manufacturers, with all data tested independently by UQ using a single test system to ensure comparisons between nozzle outputs are consistent;
  • pressure and fan angle: the user selects the spray pressure and the spray angle (for example, 110º for a 110-02 nozzle);
  • tank-mix properties: details of the tank mix (water or a pesticide selected from a list of active-ingredient products in Australia and adjuvants); and
  • outputs: once the spray set-up has been fully defined by the nozzle, pressure, angle and tank mix, the relative performance indices are shown on the right of the calculator screen.

While the list of products is not exhaustive, the calculator can be updated as new products are tested. The calculator will also be updated to refine spray-coverage assessments for different types of targets.

In some situations operators may wish to consider alternative set-ups to improve spray coverage for efficacy reasons. The calculator will allow them to do this and at the same time show changes in the amount of fines (drift-prone droplets) produced and other parameters critical to making an informed decision.

The researchers intend to use industry feedback to develop the calculator as an app for smartphones and tablets.

Screenshot of Ground Spray app

Left: Ground Spray app opening screen: many apps can provide spray-quality information based on spraying water, the University of Nebraska–Lincoln app provides droplet size data on a limited range of tank mixes. Right: Ground Spray app data input screen: spray operators can use the app to compare the outputs of a range of nozzles.


Ground Spray app

A smartphone app that compares nozzles from different manufacturers is being developed by researchers from the University of Queensland (UQ) and the University of Nebraska–Lincoln (UNL) in the US.

There are apps available that provide basic information, such as the spray quality produced by a nozzle at a particular pressure; however, comparisons of nozzles are from within a single manufacturer’s range and are generally based on spraying water only.

The measurements of droplet size or spray quality for different nozzle brands are not directly comparable because the measurements may have been made in different laboratories around the world, depending on where the manufacturer is located.

The Ground Spray app – which incorporates data from UQ’s droplet size research – will help avoid confusion between multiple sources of data on sprays.

The app shows the impact of changes in the tank mix and provides an indication of the amount of small droplets produced. Currently, the app only includes a limited range of tank mixes and adjuvants, using imperial units rather than metric; however, there are plans to extend the app to include metric units.

The app is the result of links between the UQ and UNL wind-tunnel facilities, as well as those of the US Department of Agriculture, which has been supported by the GRDC to help extend the number of tools in the operators’ toolbox for essential performance data on sprays.

The Ground Spray app can be downloaded for free from the Android and iOS App stores.

More information:

Dr Andrew Hewitt,
07 5460 1307,

Contact Dr Andrew Hewitt to request a copy of the Australian Spray Performance Calculator.


App provides snappy spray assessment


Nozzle outputs respond to nozzle design and tank mix

GRDC Project Code UQ00060

Region North