Reduzierung des Ascosporenpotentials von Venturia inaequlis durch Förderung der Fallaub-Zersetzung

Summary

The aim of this study was to investigate the possible enhancement of leaf decomposition by means of different nitrogen containing products or mulching of leaves and the resulting reduction of the ascopore potential of Venturia inaequalis. For each treatment 30 scabbed leaves of 'Jonagold' were placed in wire-mesh cages with or without fleece to avoid or allow activity of earthworms, respectively. The leaves were treated as follows: untreated as a control, spraying or addition of: urea (46% N), Siapton (organic liquid fertiliser, 7% N), horn meal (organic fertiliser, 10-14% N), Radivit (decomposition enhancer, 9% N) and slightly rotted manure (0,5% N). All treatments were adjusted to a similar amount of N per m2. In addition leaves in one treatment were mulched.
The decomposition of leaves was strongly enhanced by mulching and use of Radivit in both years, irrespective of interference by earthworms. Application of urea enhanced decomposition of leaves only in the first year. In tendency, ascospore production was reduced by all treatments in comparison to the control. The lowest number of ascospores was obtained after mulching of leaves in both years. For all other treatments, the influence of the weather and application/distribution technique are discussed.