Die postinfektionelle Wirkung von Calciumhydroxid auf Konidien von Venturia inaequalis

Summary

The post-infection activity of hydrated lime against conidia of Venturia inaequalis was 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. At the conditions of the in vitro test system hydrated lime had a post-infection activity. Suspension of 5 g l-1 applied 24 h after inoculation (16 h after infection) killed all primary stromata and stopped their further development. Treatments 48 h after inoculation reduced the number of vital primary stromata to 60% of control. Treatments with saturated solutions of hydrated lime (pH 12.45) and with KOH solutions of different pH showed that a pH higher than 12.4 was needed to be 100% effective. Suspensions of calcium carbonate (6.75 g l-1) had no effect.