Abstract
Conventional and integrated fruit growers, but not organic producers, have the possibility to use thinning agents (e.g. benzyl adenine), which allow crop regulation at a relatively late stage (10-16 mm fruit size). A few surveys have shown that by reducing net photosynthesis after blossom, June fruit drop increases. This could be an interesting new approach for organic apple orchards. Since 2003, different trials have been carried out at the Laimburg Research Station on the variety Golden Delicious rootstock M9 to devise a method for practical use by fruit growers. Unfortunately, there are still several constraints to the practical application of the shading method, not least because it does not sufficiently reduce alternate fruit bearing in the following year.