Abstract
Within the Core Organic 2 Project Bio-Incrop, different preparations and products based on microorganisms were tested for their activity against apple replant disease. The trials were conducted in a greenhouse on potted plantlets on M9 rootstock, which is the most commonly used rootstock in organic apple cultivations. To prove the presence of apple replant disease, potted plantlets grown on not sterilized untreated soil were used. These plantlets were used as untreated control. The effect of the microbial-based preparations on shoot length, shoot dry weight, and leaf colour of plantlets was limited.