Die postinfektionellen Wirkungen von Kupferhydroxid und Kupfersulfat auf Konidien von Venturia inaequalis

Summary

The post-infection activity of copper hydroxide and copper sulfate against conidia of Venturia inaequalis were evaluated using an in vitro test system based on isolated apple leaf cuticles. Experiments were conducted at 20°C and treatments were applied 24 or 48 h after inoculation. Experiments were assessed by counting living primary stromata 72 h after inoculation using fluorescence microscopy and fluorescein diacetate (FDA) as a vital stain. Copper hydroxide and copper sulfate showed post-infection activity and killed primary stromata, provided the surface of the CM was kept wet. Copper hydroxide was more effective than copper sulfate and was able to kill all primary stromata 24 h after inoculation at concentrations of 116 and 231 mg l-1. Results indicate different modes of action for the highly water soluble copper sulfate and the slightly soluble copper hydroxide. Application of copper hydroxide to dry CM did not kill primary stromata. Hence, for copper hydroxide to exert post-infection activity leaves must be wet.