Two independent trials were established during the years of 2009 and 2010 with M.26 apple rootstocks and Prunus mahaleb L. seedlings in three different locations to evaluate the effect of seven organic fertilizers and amendments on the growth of rootstocks in an organic nursery in the first year of an operation. The products tested were a microbial consortium, two kinds of vermicomposts extracts, two kind of seaweeds extracts, a stillage from yeast production and a solution of titanium. Plants receiving these products were compared to untreated and minerally or organically (manure) fertilized during vegetative season. Plant growth was evaluated by measuring the increase of the root neck diameter and the height of the tallest upward growing shoot. The application of the different organic fertilizers and amendments induced significantly higher growth of both kinds of rootstocks in all locations and for each year in comparison to control and, in the majority of the cases, to the chemical and manure fertilization. However, some products (BF Quality, Micosat, Humus UP, Tytanit and Vinassa) showed a more consistent effect on the growth of tested rootstocks under different soil and climatic conditions. It can be concluded that fertilization of apple and sour cherry rootstock with organic fertilizers and amendments of different origin and composition is effective in producing of high quality plants.
