Effects of several beetroot Vinasse products on foliage decomposition and ascospore formation of Venturis inaequalis on remaining leafmaterial

摘要

In a three year research project, funded by the "Bundesprogramm Okologischer Landbau und andere Formen nachhaltiger Landwirtschaft" the effect of the beetroot Vinasse products Biorga", Biofa" and Provita" were tested with regard to decomposition and ascospore formation on Jonagold cultivars. All products were sprayed shortly before natural leaf fall in 2011-2013, each diluted to 33 % (2011, 2012) respectively 25 % (2013). The treated orchard had a uniformly high incidence of apple scab (Venturia inaequalis,). After spraying, an accurately defined amount of leaves with uniformly infestation of apple scab was picked from the trees and put outdoor into wire mesh cages during the winter. Each treatment was replicated threefold, including an untreated control. Additionally the Vinasse product "Biofa" (25 %) was tested separately only with regard to ascospore formation in comparison to an untreated control in a second trial.Leaf degradation in the mesh cages was annually observed visually between November and April. To evaluate the amount of ripe ascospores on remaining leaves in spring, spores were twice discharged using the water bath method according to Kollar (2000). Inevery year we observed faster leaf decomposition in nearly all Vinasse treatments which lead to a considerably reduced amount of leaves left at the beginning of the ascospore release season. Except in 2011 the treatment with "Biofa"- Vinasse and in 2013"Biorga"-Vinasse was not different from the untreated control. However, in the majority of cases effects was not significant because of high standard deviation. Concerning the amount of ripe ascospores on remaining leaf material, all Vinasse products showed good effects in every year. Reduction rates between 14 - 89 % compared to the untreated control was determined. Also in trial 2, treatment with "Biofa"-Vinasse lead to a reduction of ascospores on remaining leaves between 27-84% compared to the untreated control.