Summarised project results after five years of testing mechanically removing of leaf litter to prevent apple scab disease

摘要

Since October 2010 different methods to reduce the inoculum of Venturia inaequalis are tested and compared in regard to their effect on apple scab infestation. Several field experiments are conducted throughout Germany at DLR Rheinpfalz (Rhine valley), KOB Bavendorf (Lake Constance) and OON (area Altes Land). The project is funded by 'Bundesprogramm Okologischer Landbau und andere Formen nachhaltiger Landwirtschaft".In addition to reduce leaf litter by using a vacuum cleaner in spring, vinasse and yeast extract were used to speed up the decomposition of leaves. The vacuum cleaner was respectively used at the trial stations in early spring to remove leaf litter out of the orchards. Orchards were divided large-scaled into plots with and without additional use of vacuum cleaner. The application of the leaf vacuum was always connected to standard plant protection measures. The plant protection measures were applied similarly during growing season in both plots of the orchards. The same applies for the methods to reduce the inoculum by using products to speed up the decomposition of leaf litter. The aim of the project is to enable a reduced use of copper, by making lowamounts of copper working successfully against scab in conjunction with sanitary treatments.According to the soil conditions (tire tracks) and the used technique it was possible to reduce the amount of leaf litter by 39.0 to 94.3 %, when additional hand cleaning was used, the leaf litter could be removed completely. Concerning to the reductionof scab infestation on fruits, 11 of 14 trials in several years showed a positive effect. The clearest correlation between disposing the leaves and decreased scab infestation could be found in Lake Constance area.