Leaves from organic apple trees were dipped with different organic materials and leaves were placed on the orchard floor in autumn. Leaf area and the amount of ascospores of Venturia inaequalis were measured in spring. The objective of this research was to find alternatives for urea that simulate the decomposition of apple leaves and reduces the asco-spore production. In both years urea gave an increase of the leaf degradation and a significant reduction of the number of ascospores. The antagonist Coniothyrium minitans had no significant effect on the ascospore production in both years but decreased the leaf degradation. Beet pulp showed a significant reduction of the number of spores but reduced the leaf degradation rate. Applying extra earthworms increased the degradation
