Drift reducing technology (DRT) incentives program


Drift reducing technology refers most often to the technology and design of application equipment or chemical product formulation but can also include specific ways the equipment is used. The APVMA has created its new 'Drift reducing technology (DRT) incentives program' to promote and encourage the adoption of new and improved technologies and better spray drift management methods.

Details of the DRT incentives program are still being refined, and the APVMA will introduce the program over the coming months. Initially the APVMA will focus on key areas for which scientific information already exists. After assessment, the APVMA will determine whether these technologies and principles are valid DRT options that it can recognise.

Over time the DRT incentives program will continue to expand as new scientific data become available to the APVMA for assessment. Industry can assist in the development of this program, by making new scientific information available to the APVMA. This will also benefit them by providing a means for their own technologies and innovations to be assessed and possibly recognised for the improvements they could provide.

The following information is intended to introduce the concepts of the DRT incentives program and give readers an indication of how they might benefit from it as it becomes implemented. The APVMA expects to release several DRT options by the fourth quarter of 2010 (see example 1–‘droplet size categories’). The addition of further elements will occur as new scientific information becomes available.


In 2002 the APVMA began a concerted effort to strengthen its capacity in the science of spray drift risk assessment. That effort has been ongoing and in 2008 resulted in the publication of APVMA Operating Principles in Relation to Spray Drift Risk. Since then the APVMA has been applying these principles to all new products. In 2010 it began a series of reviews specifically aimed at updating labels for currently registered products to incorporate new instructions to better manage risks from spray drift as identified from spray drift risk assessments.

It is important to understand that in order to protect people’s health, Australia’s environment and its international trade from unintended harmful effects of chemical use, it is necessary to assess spray drift risk based on the application technologies and methods that are used in Australia today. The APVMA cannot set spray drift label restrictions and instructions based on the best or latest technologies but must necessarily protect against the greater spray drift risk from traditional approaches that are more widely used.

The APVMA recognises that some chemical users have already moved to lower-drift equipment and methods or are considering such improvements. As outlined in its 2008 spray drift operating principles paper
(see section 8.3, page 31), the APVMA’s DRT incentives program will support chemical users who have already adopted better technologies and risk management methods, as well as provide an incentive for others to do the same.

The APVMA realises that some chemical users are concerned that the new spray drift management measures may stop them from being able to use many of these products because of their farm’s size and proximity to sensitive areas. It is important to emphasise again that the new no-spray zones that will be appearing on product labels are designed to provide spray drift risk protection from application with equipment known to be in common use. But modern alternatives that may be included among the APVMA’s DRT incentives options should provide effective solutions for most situations. In addition, adopting better equipment and methods is also likely to reduce chemical costs by reducing the waste of pesticides lost to off-site drift.

Who will the DRT incentives program be for?

The DRT incentives program has been created to benefit all chemical users by providing a way for them to have access to smaller no-spray zones as a result of taking up validated DRT options.

The program can also benefit manufacturers of chemical products and application equipment by providing a way for their improvements to low-drift technology to be recognised and rewarded.

  • Registrants that have developed a chemical product-specific DRT such as a new low-drift formulation can supply data to support a registration for that product with its improved low-drift performance recognised on the product’s label.
  • Manufacturers of application machinery, nozzles and other adaptations to application equipment that can reduce spray drift—namely technologies that are not limited to a specific product—can supply scientific data to support a quantitative assessment of the degree of improvement compared to conventional methods. The APVMA can then make those DRTs that it approves available to all chemical users through a permit mechanism.

How will the DRT incentives program work?

The concept of the DRT incentives program is that chemical users who adopt equipment and methods recognised for reduced spray drift risk can have access to smaller no-spray zones (buffer zones) than those that are shown on product labels. User access to these reduced no-spray zones is made lawful by means of a special permit that the APVMA issues after it validates a particular DRT or, for the case of product specific DRTs, by registration of a new product with a new label.

Issuing a permit or registering a new product is the final step. The first step will be submission of scientific information to the APVMA for assessment. In the coming months the APVMA will define how that is to be done and will define data requirements for various categories of DRTs. A permit supporting a proposed DRT can only be issued after the APVMA has assessed the data and decided that its reduction of spray drift risk as compared to conventional approaches is valid.

A DRT that is specific to a particular chemical product will be supported by information on that new product’s label. DRTs that are not chemical product specific (for example, improved application machines or new low-drift nozzles) would be made available to all who take up a new DRT. Users would need to follow instructions and information on the permit issued for that DRT.

For all chemical users, the permits will be made widely available through State and Territory departments of agriculture or the environment, through pesticide resellers and from pesticide manufacturers.

Examples of possible DRT incentives

There are many newer DRT technologies already available and more still in the development stage. The APVMA cannot issue a permit for any of them until it has adequate scientific data that show how much of an improvement the particular DRT equipment or method provides. At the beginning of the DRT Incentive Program, the APVMA will assess those options for which it has data and will provide guidance to industry in relation to which areas it sees promise for future options to be made available.

The APVMA does not have its own research facilities and must rely on outside sources to provide relevant data. The APVMA is willing to use valid scientific data from overseas sources provided that the studies apply to Australian conditions.

It should be understood that the examples that follow are not exhaustive but are technologies that potentially can be implemented sooner than other possibilities. The APVMA will welcome additional suggestions from industry and particularly those with supporting scientific data.

Droplet size categories

The APVMA is currently assessing key studies to provide alternatives to users of pesticides that require a coarse droplet size category. The APVMA expects to have access soon to new data that will enable development of ‘Standard Scenarios’ for ground application using very coarse and extremely coarse droplet size categories.

Ground application

These two new scenarios will enable a safe reduction of ground application no-spray zones that currently are being implemented on some product labels through systematic spray drift reviews. When validated and approved, a DRT permit can be issued to make use lawful for the smaller no-spray zones calculated for these two new scenarios and explain how each can be used. The APVMA expects to be able to progress this option as a priority.

A question that will arise is–will these herbicides still perform well with the larger spray droplet sizes? The APVMA will settle this question as part of any permit development by seeking information from product manufacturers. At present, the APVMA has received numerous anecdotal reports that both 2,4-D and glyphosate herbicides are fully effective with Very Coarse and Extremely Coarse droplet size categories.

Aerial application

Similar larger droplet size categories for aerial applicators are already available through the APVMA’s spray drift modelling capability. The aerial agricultural industry is working with the APVMA on developing these options. The primary consideration rests on assurance that aircraft will be able to produce the larger droplet size categories reliably.


Nozzles are one of the richest opportunities for better DRT options, and lower-drift nozzles are one of the simplest and least expensive improvements for users to adopt. The APVMA is currently working with overseas regulators to gain access to data that will allow it to quantify improvements provided by specific nozzles or nozzle groups. When the data can be assessed and verified, the APVMA can add appropriate DRT permits based on superior nozzle types.

In particular, the APVMA encourages the uptake of nozzles that have specifically been shown to produce fewer of the most drift-prone fine droplets. Some nozzles tested in wind tunnels with droplet distributions measured by laser methods have been shown to produce much lower proportions of ‘fines’ as compared to other nozzles classified in the same ASAE droplet size category.

When suitable data are available for assessment, the APVMA can support such proven nozzles with specific DRT incentives. The APVMA encourages nozzle manufacturers to undertake this kind of testing but expects testing protocols to meet scientifically rigorous standards. Interested parties should contact the APVMA for guidance.

Non-volatiles added to spray tank mix for aerial application

For most spray applications, water is the carrier solvent, and spray droplets can shrink rapidly due to evaporation under typical Australian conditions. That droplet shrinkage leads to greater spray drift. Adding compatible non-volatile material to the tank mix imposes a greater minimum mass on each droplet—a change that can substantially reduce spray drift for aerial applications (see Operating Principles, pages 22 and 23).

The APVMA’s modelling capability for aerial applications enables it to determine quantitative reductions in aerial no-spray zones for added non-volatile material. These reductions can be quite substantial for some situations such as for the no-spray zones being imposed for a number of herbicides.

The APVMA invites industry bodies to provide scientific information to support specific non-volatile additives that can be shown to be safe for the environment and that do not interfere with the efficacy of the intended product that each additive is to be used with. For example, some additives such as ammonium sulphate are already in common use with certain herbicides. Urea or crop oils are two other possibilities.

The potential reduction of spray drift becomes substantial at rates of 2 kg/ha or higher of added non-volatiles. A practical upper-limit would depend on the cost of the material and its possible hazard properties that could lead to risks at higher application rates.

Improved aircraft configurations

The APVMA’s modelling capability for aerial applications enables it to determine quantitative reductions in aerial no-spray zones for certain changes to the typical configuration of aircraft as currently considered in the APVMA’s standard risk assessment scenarios. The existing scenarios have been designed to reflect current practices that are common among aerial applicators.

The APVMA has encouraged the aerial application industry to develop a set of practicable configuration changes that taken together lead to a substantial reduction in spray drift. That development effort is currently in progress.

Sprayer shields and shrouds

Shields and shrouds added to ground application spray booms have the potential to significantly reduce spray drift. However not all implementations of these devices are equally effective and some designs can even cause worse problems under some conditions.

The APVMA encourages manufacturers of these devices to provide it with scientific data that quantifies the degree of spray drift reduction and clearly defines what conditions are paramount for proper performance.

Tunnel and tower sprayers for orchards and vineyards

The standard risk assessment scenarios that the APVMA uses for orchards and vineyards are based on radial airblast machines that have been the most commonly used spray equipment in orchards for decades. However new machine designs that provide greater control over the direction and speed of droplet-laden air have the potential to significantly reduce off-target spray drift.

At present the APVMA has no data that would allow it to assess the degree of improvement for any of these newer machine designs. The APVMA invites manufacturers to provide it with suitable scientific data that could demonstrate how much improvement each machine can provide. These data will need to meet proper scientific standards. For new studies being planned, study sponsors should contact the APVMA for consultation on study protocols.

Barrier vegetation and artificial screens

Plant hedges and tree rows as well as artificial screens have the potential to reduce spray drift in certain situations. Their effectiveness is variable depending upon their height, width, density and arrangement. Barriers that allow little or no air to pass through force the wind to move up and over, but the wind drops down again beyond the barrier at a distance related to the barrier’s height. Barriers with fine, but relatively open foliage can allow more air to pass through while providing a filtering effect, but quantifying the degree of protection is difficult in relation to real-world plantings of different species types and age.

Although mixed vegetative barriers of the right porosity, height and width can provide effective protection to sensitive sites that are very near where spray applications need to occur, they require significant time to become established and are vulnerable to degradation from repeated exposure to herbicides. Artificial barriers are expensive and only economically practical in quite limited situations.

The APVMA is presently seeking data that might allow the development of standards such that the APVMA can make specific allowances for spray drift barriers. At present, because of variability in the structure of different types of barriers and the changing nature of living plant canopies over time, it appears likely to be difficult to validate specific no-spray zone reductions for such barriers without on-site inspections or other mechanisms. Industry comment is invited.


Some adjuvants have long been promoted as being capable of reducing spray drift. For a very small number, some studies have provided partial support for this claim. However for a much larger number, there are studies indicating that many adjuvants provide no benefit and many others actually increase spray drift under certain conditions. One of the greatest problems is that some adjuvants behave differently with different tank mixes and differently again when being used with different droplet size categories.

At the present time the APVMA does not have sufficient scientific data to allow it to make quantitative judgements about which adjuvants might improve performance under which circumstances. The APVMA invites industry to provide rigorous scientific data that can provide unambiguous answers for specific adjuvant performance in specific application situations.

Water depth and risk to aquatic environments

Some no-spray zones are imposed to protect nearby aquatic environments. The APVMA uses risk assessment advice from the Department of the Environment, Water, Heritage and the Arts (DEWHA). DEWHA has long-standing approaches to assessing risk to aquatic environments within the largely dry Australian environment. The APVMA has received suggestions that it should follow the Canadian approach which recognises that deep bodies of water will be less contaminated by a given amount of pesticide than shallow bodies of water. Canada does this by allowing a reduction of buffer zone size near deep water bodies as compared to label no-spray zones based on shallow water bodies.

It is important though to note that Canada allows no buffer zones to be reduced near wetland areas or river and stream environments—these are always protected with the full-size, label buffer zones.

At this time the APVMA does not consider it appropriate to relax protection for aquatic areas based on differing water body depths. Shallow and temporary water bodies are much more the norm in Australia as compared to Canada. And the APVMA also considers it appropriate to take the same approach as Canada in not allowing no-spray zone reductions near wetlands or riparian environments.

The future

As approved DRT options are made available through this program, the APVMA will publish these on its website. In future, chemical users can check the APVMA website to keep abreast of any new DRT options as they are validated.

Agricultural chemical product registrants and application equipment manufactures will need to provide valid scientific data on possible new DRTs for assessment by the APVMA. In coming months the APVMA will publish information on the application process, and provide some general guidance on the types of data needed for the APVMA to assess the effects of any new DRT on drift deposition.


To protect your privacy, please do not include contact information in your feedback. If you would like a response, please contact us.