In the Central Zone Steering Committee (CZSC) it was decided that as of 01. January 2020 onwards for new products in high growing crops like pome fruit, vine grape, and high growing vegetable crops only applications with an efficacy evaluation based on the leaf wall area approach will be accepted (see Bullet Points in CIRCABC). Herewith the application rate is expressed according to the treated leaf wall area (defintion see below) [e.g. kg or L/10,000 m² leaf wall area] and not according to the ground area [e.g. kg or L/ha ground area]. This expression will be an additional information in the GAP to the single application rate (incl. water volume) and the rate per crop or season (total dose), which will be expressed as usual. A differentiation of the application rate according to developmental stages of the crops, plant heights, or crown heights will no longer be used. In the GAP table, the application rates with respect to the leaf wall area should also be specified in columns 10-12 (application rate).

As of 1 January 2020 application dossiers will only be accepted when they are prepared according to the leaf wall area concept. Therefore, it is mandatory that the efficacy studies were conducted according to the leaf wall area concept. The EPPO standard PP1/226(2) Number of efficacy trials usually requires 2-year efficacy trials. That means from 2018 onwards, all submitted studies will have to be carried out according to the leaf wall area model. Studies based on the previous dosing models - such as different application rates depending on developmental stages (BBCH) or plant heights - can then no longer be accepted.

When carrying out the efficacy studies in high growing crops, it is always necessary to document the geometric data of the test facilities, as explained in EPPO Standard PP1/239(2). These documentations should also be carried out for crops (e.g. ornamentals, hops, stone fruits, berries), for which the leaf wall area concept is envisaged. Only then it can be guaranteed that in future these studies can still be used following the introduction of the leaf wall area concept.

The evaluation of residue studies is currently carried out as before on the basis of the application rates, which are based on one hectare ground area. But even in these studies, the geometric data of the test facilities should be recorded, so that the application rates can be converted according to the leaf wall area.

Also for renewal applications the change of dose expression to the leaf wall area concept is planned. The transition to expressing the dose according to the leaf wall area will also be necessary for renewal applications. Therefore, a separate information will be published.

Defintion leaf wall area

The leaf wall area is defined not only as a foliage wall in the strict sense, but by the nozzle vertically treated area as a whole. Thus, the so-called leaf wall area can include a leaf wall and also e. g. a fruit zone. A leaf wall area can also only describe a part of a leaf wall e.g. when only a fruit zone of grape vines are treated or when the trunk area of vine grapes are chemically treated to get rid of stump shoots. Consequently, the treated leaf wall area results from the oversprayed area, which is created by the open nozzles.

Not all crops can be considered as high growing crops at all developmental stages, e.g. vegetable crops. At an early stage of development (low plant height), such crops are usually still treated as a surface crop in which the spray boom is guided parallel to the earth's surface (areally or as a band application); only at a later developmental stage, a leaf wall is treated vertically by a boom sprayer as usual in high growing crops. However, the instruction of e.g. per 10,000 m² leaf wall area as actually treated area can also be used here, meant as parallel treatment of the soil surface at an early development stage, later as a vertically treated leaf wall area. The information always refers to the spray belt produced by the opened nozzles.

Formulas to calculate the target area to be treated for a one hectare field

(Partial) ground area to be treated:
Partial ground area to be treated [m²/ha ground] =
width of the spray band [m] x 10,000 m² / row distance

Example for a spray band application of a band width of 0.5 m and a row distance of 1 m:
= 0.5 m (spray band width) x 10,000 m² / 1 m (row distance) = 5,000 m² to be treated area / ha ground.

Treated leaf wall area when both sides are treated:
Treated leaf wall area [m²/ha ground] =
spray band height [m] x 2 (both sides) x 10,000 m² / row distance [m]

Example for a typical leaf wall area in vineyards when the leaf wall area is treated on both sides of the wall:
= 1.6 m (spray band height/ height of the leaf wall) x 2 (both sides treatment) x 10,000 m² / 2 m (row distance) = 16,000 m² to be treated leaf wall area/ ha ground.

Year of issue 2018
Date 16.02.2018