Influence of fire blight resistant rootstocks on vegetative and generative parameters with the apple cultivar 'Topaz' in replanting orchards under organic conditions

From 2011 to 2017, the rootstocks MM111, M7, CG41, CG13, CG11, CG16 and M9 T337 with interstem, were tested at the experimental station Haschhof in comparison to the commonly used M9 T337 (with standard grafting height) with the variety 'Topaz' under organic production and replanting conditions. Regarding specific fertility, only the medium-vigorous CG41 could compete with M9 T337 and M9 T337 with interstem and could be interesting in the future because of its robustness to replanting conditions, virus infestation, fire blight, phytophthora, woolly aphid and winter cold for fertile varieties under replanting conditions, if the problem of poorer reproducibility is solved.