Abstract
The fungal diseases apple scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha), and Gleosporium (G. album, G. perennans and G. fructigenum) are the main challenges in organic apple growing. The traditionally used means of regulation like copper, sulphur, lime-sulphur, and acid clay are increasingly coming under criticism due to various problems. Therefore, the working group Organic farming at Laimburg Research Centre has been intensively searching for alternatives in recent years. Several plant extracts, plant strengthening agents, and other alternatives have been tested in the field. It was found that the alternatives available to date could hardly achieve the effect of the traditional reference products.