INFLUENCE OF WATER VOLUME AND DROP SIZE IN RASPBERRIES

Abstract

The main disease in raspberries is Botrytis fruit rot. For a good control 3 or 4 treatments with chemicals during the flowering period are needed. A questionnaire in 2010 revealed that the raspberry growers use a wide range of water volumes (300 to 1000 L per hectare) and also apply different nozzles resulting in different drop sizes. In 2010 we started a project to optimize the chemical treatments in raspberries. We compared the application of 300, 600 and 900 L water per hectare with coarse and fine drop size respectively. We measured the deposition of the chemicals on leaves and evaluated the biological efficacy on Botrytis fruit rot and two-spotted spider mites. The deposition trials showed more chemicals on the leaves with the lowest water volume (300 L) and with coarse drop size. There was no correlation between the deposition on the leaves and the control of Botrytis fruit rot and the spider mites. All treatments gave a good result in controlling Botrytis fruit rot, with no differences between the variants. The spider mites live on the bottom side of the leaves. There was no efficient control from the different water volumes. Further trials showed a better efficacy, we used a water volume of 1.800 L per hectare and the air volume was increased from 25500 m 3 per hour to 35800 m 3 per