Crop-adapted crop protection measures in high-growing greenhouse vegetables

Currently the grower of glasshouse crops such as tomatoes, cucumbers, eggplants or sweet pepper does not have a clear guidance on how to adapt the dosage of fungicides, insecticides or acaricides to his growing crops. In most cases the total leaf area of the crop represents the target area for the application of crop protection products against diseases and pests. Preliminary measurements on eggplants, cucumbers and sweet pepper show that the total leaf area can be adequately estimated by the leaf wall area which is easy and quick to determine. More measurements will be necessary for tomatoes since the many varieties and forms of cultivation complicate matters here considerably. As a tentative model to estimate the total leaf area the leaf wall area is suggested whereby a leaf wall area of 20 000 m² per hectare would correspond to a single strength spray broth volume of 1000 liters per hectare. Similarly to models used in fruit-, berry- and grape production, the dose of the crop protection product would be increased or decreased linearly in relation to a greater or smaller leaf wall area. This tentative model must be tested and verified through further experiments and measurements. In addition to better crop adapted dosage of crop protection products current spray equipment used in glasshouses must be improved so as to achieve an even spray deposit on the entire canopy and a high rate of product recovery on the crop.