With a change in formulation, no further work to demon-

strate the minimum effective dose is required where formu-

lation

does

not

markedly

increase

efﬁcacy.

Where

formulation change has been shown to markedly affect efﬁ-

cacy, then one or more additional doses, lower than that to

be recommended should be included in the effectiveness

trials to provide justiﬁcation that the proposed dose is the

minimum effective dose (guidance under development).

Efﬁcacy testing to establish the minimum

effective dose

Preliminary tests

During the early development of a plant protection product,

initial dose-ranging trials, possibly in laboratory or semi-

ﬁeld situations, provide an indication of the likely recom-

mended dose. Data from such trials can then be used in

reﬁning the doses to be applied in subsequent ﬁeld trials to

test the effectiveness of the product. These trials focus on

doses around the dose necessary to deliver the required

level of effectiveness and enable a recommended dose to

be proposed.

Direct efﬁcacy trials

To provide sufﬁcient information to substantiate the direct

efﬁcacy (effectiveness) of a product, a number of trials,

making up a trial series, would normally be conducted in

which at least the proposed recommended dose is tested.

This trial series will include a relevant range of climatic,

agricultural, epidemiological and edaphic conditions and

appropriate

standards

reference

products

(preferably

the same if available in all countries). EPPO Standards

PP 1

Efﬁcacy evaluation of plant protection products

pro-

vide more detailed instructions on the design and conduct

of efﬁcacy trials for individual host/pest combinations. For

further guidance, refer to EPPO Standards PP 1/181

Con-

duct and reporting of efﬁcacy evaluation trials, including

good experimental practice,

and PP 1/152

Design and anal-

ysis of efﬁcacy evaluation trials.

To provide information to establish the minimum effec-

tive dose, some of the trials conducted to demonstrate efﬁ-

cacy should include at least one lower dose(s) (for example

–

80% of the recommended dose) to that which would be

recommended. Preliminary data may also be used to sup-

port the justiﬁcation of the minimum effective dose. The

number of trials in which a lower dose is included should

be sufﬁcient to cover the range of situations in which use is

proposed, and demonstrate differences in control (or effect

for growth regulators) between the lower dose and the rec-

ommended dose. Where the recommended dose can be

identiﬁed as the minimum effective dose from preliminary

tests and efﬁcacy trials, with lower doses meeting the crite-

ria, no additional trials are necessary to establish that the

dose recommended is the minimum necessary for efﬁcacy.

Where situations have been identiﬁed that allow reduced

rates to be employed without compromising the desired

effect, they should appear as recommendations on the label,

e.g. where reduced rates are giving satisfactory control of

speciﬁc weed species or pathogens, or where reduced per-

sistence is acceptable, or on particular soil types where a

lower dose is fully effective and gives no danger of reduced

sensitivity or resistance.

Multiple target pests and multiple dose

recommendations

Many plant protection products are used to control a range

of target pests. In such situations, it would be impractical

and

unnecessary

provide

evidence

for

the

minimum

effective

dose

for

all

recommendations.

Information

required for a range of targets which are considered to be

the most important, and for which control provides the

major agricultural beneﬁt. It should be noted that where the

proposed use is across a substantive geographical area such

as an authorization zone (as deﬁned in PP 1/278

Principles

of zonal data production and evaluation

), the major target

species and/or the major crop may vary and there may be

differences

population

pressures.

Therefore

particular

consideration should be given to trials location.

Similarly, where different doses are recommended for

different target pests, it is not necessary to produce data for

every dose or for every target on the label. For example,

where lower doses are recommended (e.g. for the control of

less signiﬁcant or susceptible target organisms, for situa-

tions of low incidence or for use with resistant cultivars),

information from a dose or doses other than that recom-

mended is usually not needed. Data is required for the main

targets or some representatives of them.

Reference

(2009) Regulation (EC) No 1107/2009 of the European Parliament

and of the Council of 21 October 2009 concerning the placing of

plant

protection

products

the

market

and

repealing

Council

Directive

79/117/EEC

and

91/414/EEC.

Ofﬁcial

Journal

the

European Union L

309

, 1

–

50.

404

Efﬁcacy evaluation of plant protection products

2012 OEPP/EPPO,

Bulletin OEPP/EPPO Bulletin

, 403–404