1. Introduction

An agricultural adjuvant is generally described as any substance (other than water) that is added to an agricultural chemical product to alter its physico-chemical properties and/or improve its efficacy. As the intended use of such products is 'to modify an effect of another agricultural chemical product' they meet the legislative definition of an ‘agricultural chemical product’ under Section 4 of the Agricultural and Veterinary Chemicals Code Act 1994 (the Agvet Code) and require registration.

General information on how to register an agricultural chemical product is available on our website.

Applications to approve, register or vary active constituents, products, or labels of agricultural chemical products must be made to the Australian Pesticides and Veterinary Medicines Authority (APVMA). An application must be supported by information that allows the APVMA to determine whether we are satisfied that the product meets the applicable statutory criteria (safety, trade, efficacy and labelling criteria).

This guideline addresses how the APVMA classify adjuvants and outlines the specific registration requirements for agricultural adjuvant products and how the criteria for safety, efficacy trade and labelling can be satisfied.

2. Classification of adjuvants

The APVMA accepts the standard adjuvant terminology as outlined by the American System for Testing Materials (ASTM) Committee E-35 on Pesticides and Alternative Control Agents and, more specifically, the Committee E35.22 on Pesticide Formulations and Delivery Systems1.

Agricultural adjuvants fall into 2 main categories depending upon their functional properties:

  1. Adjuvants that enhance the efficacy of the pesticide active constituent.
  2. Adjuvants that improve the ease of application.

The functional groupings of adjuvants are described below. This list is not exhaustive but provides examples to illustrate how adjuvant products broadly fit into these functional groups. A single adjuvant may perform one or more of these functions simultaneously.

2.1. Adjuvants that enhance product efficacy

a) Wetters/spreaders (enhance adhesion to and spreading of spray droplets on target surfaces by reducing the surface tension of the pesticide formulation and improving coverage), which may include:

  • non-ionic surfactants
  • anionic surfactants
  • cationic surfactants
  • amphoteric surfactants
  • organo-silicate surfactants
  • acidified surfactants.

b) Stickers (increase the adhesion of pesticides to target surfaces), which may include:

  • latex-based
  • terpene/pinolene
  • pyrrolidone-based.

c) Penetrants (improve the transfer of active ingredients from the target surface to interior tissues), which may include:

  • mineral oil
  • vegetable oil
  • esterified vegetable oil
  • organo-silicate surfactants
  • acidified surfactants.

d) Extenders (enhance the amount of time the active ingredient remains effective by increasing resistance to environmental degradation), which may include:

  • ammonium sulphate
  • menthene-based.

e) Humectants (increase the density or drying time of an aqueous spray deposit), which may include:

  • glycerol
  • propylene glycol
  • diethyl glycol.

2.2. Adjuvants that improve ease of application

a) Acidifying/buffering agents (adjust the pH of alkaline or acidic water and minimise decomposition of the pesticide through alkaline hydrolysis).

b) Anti-foaming/de-foaming agents (reduce or suppress the formation of foam in the spray tank, preventing foam overflow), which may include:

  • dimethopolysiloxane.

c) Compatibility agents (permit the mixing of different agrochemicals by preventing antagonism between different ingredients in the spray solution), which may include:

  • ammonium sulphate.

d) Drift-reducing agents (alter the viscoelastic properties of the spray solution, yielding a coarser spray with greater DV0.1 and DV0.5 droplet sizes):

  • polyacrylamides
  • polysaccharides.

Note that the APVMA expects to release a separate guideline for demonstrating the efficacy of drift-reducing agents. Before this guideline is released, any applicant wishing to register an adjuvant product containing a drift-reducing agent should contact the APVMA for more information on the data requirements for this category of adjuvants.

e) Dyes (commonly used for spot- or boom-spraying herbicides to detect missed spots or avoid spraying a plant or area twice).

f) Water conditioners (prevent a reaction between hard water ions in spray solutions and suppress the formation of precipitates or salts), which may include:

  • ammonium sulphate.

3. Active constituent approval

The active constituent in an agricultural adjuvant product is the chemical within the product which is primarily responsible for the adjuvant function claimed on the label. This claim may be as a wetter/ spreader, penetrant, sticker, humectant or extender. The Agvet Code requires the APVMA to approve active constituents separately to the registration of a product.

When making an application you will need to identify which of the following applies to the active constituent and this will determine the data requirements for approval of the active constituent:

4. Product registration

Applications made to the APVMA to register or vary products must be supported by information that allows us to determine whether we are satisfied that the product meets the applicable statutory criteria (safety, efficacy, trade and labelling criteria). Applicants must address each of the statutory criteria through the provision of data, nomination of a reference product (with appropriate consent to access confidential commercial information and protected information) or scientific argument.

When a reference product is nominated and appropriate consent is provided, the APVMA can compare the proposed product to the reference product (concentration of active, formulation, formulation type, label claims etc.) to determine the similarity of the proposed product to the reference product. If the APVMA determines that the proposed product is similar or closely similar to the nominated reference product as defined in Clause 1.2 of Schedule 6 of the Agricultural and Veterinary Chemicals Code Regulations 1995, a reduced assessment may apply.

4.1. Safety

A chemical product meets the safety criteria if use of the product, in accordance with any instructions approved or to be approved by the APVMA or contained in an established standard:

  • is not, or would not be, an undue hazard to the safety of people exposed to the product during its handling or people using anything containing its residues
  • is not, or would not be, likely to have an effect that is harmful to human beings
  • is not, or would not be, likely to have an unintended effect that is harmful to animals, plants or things or to the environment.

The matters which the APVMA must have regard to in being satisfied whether a chemical product meets the safety criteria are separated into the risk areas of: chemistry and manufacture, toxicology, metabolism and kinetics, residues, occupational health and safety, and environment; each of which has specific data requirements.

4.2. Chemistry and manufacture

Details of the chemistry and manufacture aspects of the proposed product to be included in the applications are outlined in chemistry and manufacture (Part 2). If details are unknown to the applicant, arrangements should be made for their provision on a commercial-in-confidence basis from the owner of the trademarked constituent. This applies to both active and non-active constituents in the formulated product.

4.3. Toxicology

In some cases adjuvants may themselves be toxic or, alternatively, their addition to a pesticide product or mixture may increase the hazard and toxicity of that product. Toxicology data on the formulated adjuvant product and its active constituent(s) may be required to support an application for product registration.

The toxicology data required depend on the nature of the application. A comprehensive toxicological assessment report will be required where an application is submitted for a new adjuvant product that contains a new active constituent not previously approved by the APVMA. A reduced toxicological assessment would be required where the application is for a new product incorporating an existing adjuvant active constituent that has a new chemical formulation or has undergone a major formulation change. Where a suitable reference product has been nominated and appropriate consent to access to information regarding the reference product is provided, toxicological data may not be required.

4.4. Metabolism and kinetics

Metabolism studies are used to assess the nature and disposition of chemical residues in, or on, food or feed commodities. The composition of the residues (the parent compound and/or metabolites) and where they occur in a crop or farm animal must be known so that supervised residue trials, processing trials and analytical methods deal with the relevant residues. Data on metabolism and kinetics is not generally required unless there is a residue of toxicological concern or the applicant is seeking to register a new active constituent.

4.5. Residues

A residues assessment may be required if there are residues of toxicological significance or in circumstances where the adjuvant is likely to change the residue profile and/or withholding period of the product to which the adjuvant is added. The use of an adjuvant in combination with a pesticide may result in higher pesticide residues in the treated commodities, due to enhanced uptake or prolonged persistence of the pesticide.

When registering an adjuvant that is not similar to a nominated reference product, or where the use of an adjuvant has not been considered in relation to the use of a registered pesticide product, it may be necessary to conduct residue studies on the pesticide–adjuvant combination or to present an argument that the addition of the adjuvant will not lead to increased residues. If the claims for an adjuvant are generic (i.e. the use is proposed in situations where ‘an adjuvant is recommended’), it must be demonstrated that the pesticide residues in the commodity are equivalent to those where other adjuvants are used. Trials will need to be conducted with a representative range of pesticides (herbicides, fungicides, insecticides) in several crops in order to demonstrate that residues comply with existing maximum residue limits.

If the adjuvant is considered to be of toxicological significance residue data for the adjuvant itself may be required. In these situations, the applicant must submit a full residues data package.

If residues data is likely to be required the applicant may wish to seek pre-application assistance to determine the type of data which would satisfy the APVMA.

4.6. Occupational health and safety

The potential impact on the health and safety of those who may be exposed to a product or its residues under normal working conditions needs to be assessed and appropriate safety directions set. When registering an adjuvant that is not similar to a nominated reference product, information or data that will allow for the estimation of worker exposure will be required. This data would include the application rate (L/ha), area treated per day and application method.

4.7. Environment

When adjuvants are applied, they are released directly to the environment along with the pesticide with which they are combined. When registering an adjuvant that is not similar to a nominated reference product, environmental data or information may be required. Environmental data requirements vary depending on the nature of the adjuvant and its proposed use pattern.

Adjuvants may change the way liquids behave, which can affect the droplet spectra and drift potential of pesticide spray. Off-target exposure may be amplified compared to when the pesticide is applied alone. Applicants should provide data or argument to describe the likely effect of the adjuvant on the drift potential of the agricultural chemical product(s) with which it will be combined.

Information relating to the toxicity of the adjuvant to non-target plants, wildlife, fish and other organisms is required unless it can be demonstrated that exposure to these non-target organisms will be minimal. Where exposure to non-target organisms is identified, information provided should include data or argument to assist in determining whether the adjuvant is likely to alter the toxicity of the chemical product(s) with which it will be combined.

4.8. Efficacy

If each active constituent of the proposed product is used in one or more other registered chemical products for an equivalent use (that is, for an equivalent pest or purpose at equivalent rates of active constituent application) then the product is assumed to be effective under the legislative instrument Agricultural and Veterinary Chemicals Code (Efficacy Criteria) Determination 2014. It does not imply that the product is safe to use on each of the nominated crops in terms of crop safety and separate crop safety information or argument may be required.

If the proposed product does not meet the efficacy criteria outlined above, then stand-alone efficacy data should be provided.

Agricultural adjuvants fall into 2 main groups depending on their functional properties and each group is considered separately with regard to the information that would be required to demonstrate efficacy.

  • Adjuvants that enhance the efficacy of the pesticide active constituent.
  • Adjuvants that improve the ease of application.

4.8.1. Adjuvants that claim to enhance product efficacy

The applicant should provide data to establish that the adjuvant product improves the efficacy of the pesticide with which it is to be mixed/used and demonstrate that the product does not cause untoward damage to the target crop. The efficacy experimental design and analysis guideline provides advice about designing efficacy trials and may be used as a checklist of design principles. The guideline does not include all matters relating to trial design and analysis and you are encouraged to seek advice from a professional biometrician or statistician when planning trials.

When planning trials with adjuvants the following should be considered:

  • Trials should be conducted using the recommended maximum and minimum rates of the adjuvant and should compare the efficacy of the pesticide product alone (with no adjuvant) to the pesticide used with the adjuvant at the label rates.
  • The pesticide should be applied at the rate specified on the pesticide label.
  • If a range of rates is recommended on the label, efficacy studies should be undertaken using a suitable range of rates including the maximum and minimum rates.
  • If the proposed rate of pesticide in a tank mixture differs from the recommended pesticide rate when that product is used alone, supporting data for the change in rate should be provided.
  • Application equipment should be calibrated. The water application rate should be the same as recommended on the label and water quality (for example pH, hardness, salinity) should be reported.
  • Applicants should provide a record of weather conditions before and after application, and during the period that the efficacy is evaluated.
  • The range of application methods approved for the pesticide should be tested using the pesticide–adjuvant mixture if appropriate.
  • As the addition of adjuvants can change how liquids disperse and therefore alter the droplet spectra produced by an atomising unit, at least one trial should be undertaken showing that any alternative application methods (or nozzle types) provide comparable results to the principal method of application.
  • Phytotoxic effects should be measured at maximum rates for both pesticide and adjuvant. If unacceptable crop damage results, then further trials at reduced rates will be required to demonstrate an acceptable level of crop safety. Any observable damage should be scored and details recorded and reported.
  • If an adjuvant interacts with a pesticide in such a way that it changes the rate and amount of uptake of the active constituent by the target organism it may affect the potential for resistance development or necessitate a change to the resistance management practices for the active. If the adjuvant has a potentiating effect, then argument or data should be provided to address the impact of the potentiation on resistance management practices.
4.8.1.1. Trial requirements specific to pesticide type
4.8.1.1.1. Herbicide and adjuvant
  • Field experiments using replicated treatments on multiple trial sites over a range of agro-climatic conditions
  • Statistically valid design
  • Untreated control included (control)
  • A standard reference treatment using the herbicide with an existing registered adjuvant recommended on the herbicide label if one exists (reference)
  • A treatment using the herbicide alone (only if herbicide can be used alone; not required for image products)
  • The range of rates used in the experiments should encompass the proposed commercial rates of both the herbicide and the adjuvant (experiment)
  • Improved efficacy determined by objective assessment methods, including quadrat weed counts, weed weights, visual rating assessments and/or crop yield
  • Increased weed spectrum controlled
  • More consistent results obtained
4.8.1.1.2. Insecticide and adjuvant
  • Field experiments using replicated treatments on multiple trial sites over a range of agro-climatic conditions
  • Statistically valid design
  • Untreated control included (control)
  • A standard reference treatment using the insecticide with an existing registered adjuvant recommended on the insecticide label if one exists (reference)
  • A treatment using the insecticide alone (only if insecticide can be used alone; not required for image products)
  • The range of rates used in the experiments should encompass the proposed commercial rates of both the insecticide and the adjuvant (experiment)
  • Improved efficacy determined by objective assessment methods, including insect counts, level of crop damage, crop yield, reduction in the number of repeat applications required
  • Increased spectrum of activity
  • More consistent results obtained
4.8.1.1.3. Fungicide and adjuvant
  • Field experiments using replicated treatments on multiple trial sites over a range of agro-climatic conditions
  • Statistically valid design
  • Untreated control included (control)
  • A standard reference treatment using the fungicide with an existing registered adjuvant recommended on the fungicide label if one exists (reference)
  • A treatment using the fungicide alone (only if the fungicide can be used alone; not required for image products)
  • The range of rates used in the experiments should encompass the proposed commercial rate of both the fungicide and the adjuvant (experiment)
  • Improved efficacy determined by objective assessment methods, including disease ratings, level of crop damage, crop yield, reduction in the number of repeat applications required
  • Increased spectrum of activity
  • More consistent results obtained

When data are conflicting, additional experiments need to be conducted until the weight of evidence allows a satisfactory conclusion to be reached.

4.8.1.2. Number of trials

If the claim is for specified weeds, pests or diseases, there should be sufficient trials to demonstrate the efficacy for each. If the claim is for a class of weeds, pests or diseases, or a comprehensive claim for the label overall, trials should be for representative weeds, pests or diseases and include significant, hard-to-control weeds, pests or diseases.

For a new adjuvant–pesticide combination, a minimum of 3 trial sites with at least one trial in each major production region conducted over 2 seasons are sufficient (provided the results are consistent) (6 in total).

For amendments to the label of a currently registered adjuvant (for example extension of use pattern), 2 experiments over 2 seasons are required (4 in total).

To establish bioequivalence to a reference product at least 2 trial sites over 2 seasons may be required depending on the degree of similarity claimed (4 in total).

4.8.2. Adjuvants that claim to improve the ease of application

Adjuvants that improve the ease of application act by altering the physical and/or chemical characteristics of the spray mixture (reduce drift, enable compatibility, improve water quality, etc.) and do not directly enhance the efficacy of the pesticide to which they are added. If data/information is required to support an application to register such a product, the data should demonstrate that any claims are valid and consistent with the active constituent contained in the product. For instance, if the proposed product is a marker, data should be provided to demonstrate that the marker dye, when added to the pesticide product, will unduly affect the crop. If the proposed product is a drift-reducing agent, data should be provided to demonstrate that the addition of the drift-reducing agent does not reduce pesticide efficacy or unduly affect the crop.

At least one trial should be undertaken for each major use pattern claimed on the label. Such a trial should include a hard-to-control weed, pest or disease.

Trial design should:

  • include a field experiment using replicated treatments
  • be of statistically valid design
  • include untreated control (control)
  • include a treatment using the product at the rate recommended with an appropriate pesticide (experiment)
  • include the pesticide product applied alone at the recommended rate (reference)
  • demonstrate the effects on efficacy and phytotoxicity determined by the presence or absence of damage. Generally, trial data collected over a range of variables such as crops, climatic zones and different pesticides are required unless it can be otherwise argued or demonstrated that the data submitted is relevant to all those variables.

4.9. Trade

The proposed use of a new product or the extension of use of a registered product on the commodities listed in the major export food commodity groups section requires the submission of trade information for those commodities if residues are above the analytical limit of quantification. If this applies, please refer to overseas trade (Part 5B) for further details of the information required for assessment.

4.10. Labelling

The Agvet Code requires that all agvet products supplied to the marketplace must have a label attached to the container. This label must state the relevant particulars, and must comply with all conditions of label approval.

While the APVMA approves relevant label particulars, it is the registrant's responsibility to ensure that the marketed label meets the requirements of the Agricultural Labelling Code in terms of label layout, printing and legibility requirements and that it does not contain information contrary to the approved relevant particulars.

While labels for agricultural adjuvant products must meet the Agricultural Labelling Code, there are a number of issues that are specific to the labelling of agricultural adjuvants:

4.10.1. Product name

A product name must not be misleading, confusing or inconsistent with other label instructions or be easily confused with the names of other registered products. The name should also describe the end use product, for example, the product name may include descriptors such as 'surfactant' or 'adjuvant' (refer to 'classification of adjuvants').

4.10.2. Constituent statements

The label must include the name and proportion of each active constituent in the product. The active constituents are those constituents that are responsible for the adjuvant product’s modifying effect. It is not acceptable to refer to ‘a blend’ of active constituents (for example you cannot declare the active as a 'blend of non-ionic surfactants').

4.10.3. Statement of claims for use

Unless the name of the product describes the intended uses, the statement of claims should include a concise description of the purposes for which the product is to be used. The statement of claims should include the adjuvant functional group as listed in the guidelines, such as wetter, sticker or penetrant. If the adjuvant product performs more than one of these functions, then each grouping should be listed.

If the product name includes descriptors such as 'wetter' or 'surfactant' it may be sufficient for the statement of claims to be simplified to 'for the use with insecticides, fungicides and herbicides'. However, if the product name is less descriptive, the statement of claims should be more descriptive and may include additional information such as 'increases droplet spread, increases chemical uptake or rain fastness'.

4.10.4. Directions for use

The directions for use should include the situation, rate and any critical comments in terms of the specific pesticide product(s) with which the adjuvant can be mixed. If the adjuvant is claimed for use with a specific product, the label of that product should not exclude the use of the proposed product by omission (i.e. the partner product label should either include the adjuvant by name in the directions for use as a mixing partner or include a general statement such as reference to the applicable group of adjuvants (e.g. 'use a non-ionic surfactant at label rates')).

4.10.5. Tank-mixing compatibility

Provide a statement or list indicating the pesticide products that the adjuvant is compatible with. Claims for the use of adjuvants with unspecified or general claims (for example herbicides, fungicides or insecticides) are not acceptable. Compatibility implies biological as well as physical compatibility unless specifically stated. Where this section refers to multiple mixes, compatibility for each mix should be established.

4.10.6. Mode of action symbol

The mode of action symbol is only required on agricultural chemical insecticides, herbicides and fungicides. It is not required on agricultural adjuvants.

5. References

American System for Testing Materials (ASTM) Committee E-35 on Pesticides and Alternative Control Agents, ASTM Committee E35.22 on Pesticide Formulations and Delivery Systems, ASTM International, West Conshohocken, PA, USA, 2008, available at astm.org/COMMIT/SUBCOMMIT/E3522.htm.

1 ASTM E1519-13, Standard Terminology Relating to Agricultural Tank Mix Adjuvants, ASTM International, West Conshohocken, PA, 2013, available at astm.org.

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