Efficacy Evaluations and Guidelines

This guidance is to help you complete the Efficacy section of a pesticide application.

What is Efficacy?

Efficacy can be defined as determining the effectiveness of a substance, including identifying the appropriate dose and mode of action, and identifying any adverse or unintended negative impacts.  In regulatory assessments, the relevant claims of the proposed product must be supported by data.  These data are generated from appropriately conducted trials, following relevant guidance and are provided to address regulatory requirements. 

Efficacy assessments for plant protection products (PPP)

Efficacy consider whether the claims made on the product labels are supported by data. HSE considers the relevance of the proposed uses to UK effectiveness, risk to the crop and resistance issues. We consider whether there is a demonstrated benefit (to the crops or in non-crop situations) and put into context with any identified adverse impacts (for example damage caused to the crop).   

HSE considers the directions on the label to ensure they are appropriate to the use of the product.  This contributes to using the product in a targeted, responsible manner optimising its' use as part of integrated control programmes with other measures, but ensuring it is the minimum required.

Data requirements and accompanying guidance

Data supporting GB and NI authorisations for a plant protection product (PPP) should follow the appropriate guidance (EPPO, see below) and address the relevant data requirements for the active substance and the formulated product.

European Plant Protection Organisation (EPPO)

EPPO is an international organization responsible for cooperation and harmonization in plant health and protection within the European and Mediterranean region.  The UK has been a member of EPPO since its creation in 1951, and membership has grown to over 50 countries.  HSE provides expertise on a number of PPP related panels and expert working groups.

EPPO produce standards on how to approach Efficacy evaluations, which are recognised in regulatory regimes, including the UK, EU, FAO and OECD.   These range from general standards addressing regulatory data requirements (such as Phytotoxicity (PP 1/135)) to standards describing the conduct of individual efficacy trials (such as aphids on cereals (PP 1/020)).  

Data generated outside the UK

Data generated outside the UK may be used to support UK products, provided there is an appropriate case for relevance to UK agronomic conditions. EPPO PP 1/278 'Principles of zonal data production and evaluation' provides a comprehensive overview of the relevant issues when generating and using regionally based data. Further information is provided in 'Efficacy Guideline 106 - General principles on generating Efficacy data'.

However, in some situations, where guidance is not harmonized via EPPO or in a limited number of UK specific situations, additional UK guidance is relevant and must be followed (eg for resistance management).

UK Additional Guidance

Below is further current guidance that applicants should refer to when making an application for uses in the UK.   Included are guides and information on UK crops/situations, with details of relevant UK targets; and UK resistance management and labelling.  This may assist applicants in trials planning,  summarising data and supporting UK label claims.  Please note that non-UK generated efficacy data may be used to support UK uses, provided there is an appropriate case for relevance to UK agronomic conditions.   In this regard, EPPO PP 1/278 provides a key overview of the relevant issues on generating and using regional data packages.  In future a range of comprehensive crop guides will be produced.

General Guidance on Generating Data and Submitting Applications

Application or Situation Specific Guidelines

Crop Safety Guidelines

303 - Effects on Non-Target Crops of Highly Active Herbicides – Including Mixtures and Sequences

Crop Specific Guidelines

Chemical and Control Specific Guidelines: Resistance Management and tank mixtures/sequences

Other efficacy related guidance

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Updated 2023-09-22