Wirkung biologisch-dynamischer Präparate in RebbergenState of the Art: The majority of vine bio-dynamic growers report positive experiences in terms of plant production but also wine quality. However, quantitative and scientifically proved data are not available. However there is a high interest of the wine growers for appoved data on the efficiency of the bio-dynamic preparations. As in other countries bio-dynamic viticulture is rapidly growing in Switzerland. However, there is very little scientific evidence for the efficiency of the preparations. Thus, science-based recommendations for its use or optimisation cannot be given. Project aims including target group: To show the quantitative effects of bio-dynamic preparations on parameters of plant growth, disease tolerance, soil properties and finally also on vine quality. An additional goal of the project is the management improvement of the bio-dynamic growers participating in the trials. The results may show possibilities to optimize the standard and the specific bio-dynamic management measures of the growers. Methodology: In 2003 the project team that includes 4 bio-dynamic growers installed an On-Farm trial on 4 different sites of bio-dynamic vine farms. At each site 4 different treatment blocks are separated: a) with preparation 500 and with prep. 501; b) with 500 alone; c) with 501 alone; d) no preparations. Several times of the year plant growth and health is assessed. Vine quality is assessed by separated microvinifcation per treatment and site. The management of the 4 vineyards is harmonized. Results, conclusion, state of the art: First results do not show differences in disease incidence. There was a tendency found for more chlorophyll in leaves where prep. 501 is applied. At two sites there was a tendency for improvement of the quality of soil aggregates where 500 is applied.ViticultureProject description