Leaf wall area and leaf area in cucumber,eggplant, sweet pepper and tomato grown in greenhouses in Switzerland

Various methods for the harmonization of the registration of crop protection products and dose adjustments in high growing crops have been discussed over many years. The leaf wall area (LWA) method has been known for some years already but it has received renewed attention due to a proposal by the European agrochemical manufacturing industry for harmonizing the dose expression in view of the new zonal registration system in the EU. The LWA method appears not only suitable for fruit trees and vineyards, but may also prove a simple and widely accepted method for dose adjustments in high growing vegetable crops particularly in greenhouses. This paper provides a dataset on leaf wall area and leaf area development for a selection of commercially grown cucumber, eggplant, sweet pepper and tomato varieties in Switzerland. Relationships between leaf wall area and leaf area have been established. A tentative product dose adjustment to growing vegetable crops in greenhouses is given for Switzerland. Biological efficacy trials will be required to validate the LWA method.