EPPO Bulletin

. 2024;00:1–8.

E P P O S T A N D A R D O N E F F I C A C Y E VA L U A T I O N O F P L A N T P R O T E C T I O N P R O D U C T S

PP 1/331 (1) Principles of efficacy extrapolations for major uses

SPECIFIC SCOPE

This Standard describes the principles to be followed

when considering effectiveness and crop safety extrapo-

lations of plant protection products applied for major

uses. The aim is to reduce the need for trial data on in-

dividual major crop and major pest situations, while

maintaining appropriate data sets by describing the

general principles that should be considered in making

extrapolations. The Standard provides guidance for

regulatory authorities and applicants in the context of

the registration of plant protection products, and for the

development of detailed lists of acceptable extrapola-

tions. The Standard does not cover plant growth regula-

tors (PGR) and plant defence inducers. Extrapolations

of identical uses between different formulations of the

same product are outside the scope of this Standard.

SPECIFIC APPROVAL AND

AMENDMENT

First approved in 2024–09.

INTRODUCTION

EPPO Standard PP 1/257

Efficacy and crop safety

extrapolations for minor uses

describes principles of

extrapolation for minor uses and is used to support the

development of a detailed list of acceptable minor uses

extrapolations presented in the EPPO Database on PPP

Extrapolation.

The principles described in the current

Standard are closely aligned to PP 1/257 but are

specifically

aimed

major

uses,

where

key

consideration is a need for a robust dataset for a major

use in order to extrapolate to other major uses. The

definition of a ‘robust’ dataset, and how to generate the

data, is provided in EPPO Standards PP 1/214

Principles

of acceptable efficacy

, with the number of trials for major

uses described in PP 1/226

Number of efficacy trials

. The

use of data in a zonal context is described in EPPO

Standard PP 1/278

Principles of zonal data production

and evaluation

The definition of ‘major uses’ varies between EPPO

countries and there is no harmonized definition for the

whole EPPO region. Key determinants include factors

such as market values and area covered and distribution

of the proposed crops, the pest impact and the scale of

use of the applied plant protection products. Examples

of extrapolations of major pests (with multiple host

crops) in minor crops are presented in the minor use

EPPO Extrapolation Database for a number of pests

(including nematodes, slugs and spider mites) with mul-

tiple hosts. Extrapolations may be used either to allow

an existing authorisation to be extended to include ad-

ditional crops (or, in the case of herbicides, other non-

crop uses) or pests in the absence of specific data, or to

reduce the extent of the data package that would nor-

mally be required to support another use. Further infor-

mation is available in EPPO Standard PP 1/226

Number

of Efficacy trials

Pests that are commonly regarded as major or more

difficult to control, and therefore requiring specific

data, are particularly relevant as key pests from which

to extrapolate. There is potentially significant variabil-

ity in pest, crop and product interactions, which can

affect the validity of any extrapolation. For this reason,

a precautionary approach should be taken for major

uses, and extrapolations should not be made from less

to more challenging control situations. The broader the

range of conditions (whether pest or crop related) under

which the product has demonstrated acceptable efficacy

(and particularly how challenging the conditions were),

the greater the scope for extrapolation without the need

for additional data.

Extrapolations should be based on applying the

plant protection product under comparable conditions

of use, for example a comparable dose and timing. It

may be possible however to have some flexibility in

certain aspects, e.g. number and timing of applica-

tions or growth stages of the crop. However, this is

dependent on differences not influencing effective-

ness or crop safety and should be supported by robust

argumentation.

Extrapolations of identical uses between different formulations of the same

product may be possible but outside the scope of this Standard. PP 1/307

Efficacy considerations and data generation when making changes to the

chemical composition or formulation type of plant protection products

discusses

criteria and data generation when comparing formulations.

EPPO Database on PPP Data Extrapolation

https://extrapolation.eppo.int/

DOI: 10.1111/epp.13035