Abstract
In spring 2017, an apple trial was planted in the experimental site 082 of the Haschhof trial station. The varieties Ilzer Rosen, Gravensteiner, Steirischer Maschanzker, Roter Berlepsch, Goldparmäne, Roter Boskoop, Cox Orange, Winterbanane, Kronprinz Rudolf, Rubinette, Braeburn and Elstar were grafted onto the rootstocks MM111, M7, B9 and CG11. A multi-leader system was trained on MM111 and M7, and a longitudinal spindle fruit wall was trained on B9 and CG11. After five years of organic production, Braeburn and Winterbanane achieved the significantly highest yields. Cox Orange and Roter Berlepsch performed worst. Surprisingly, the varieties on the vigorous rootstocks MM111 and M7 as a multi-leader system achieved similarly high yields per square metre of a tree as on the dwarfing rootstocks B9 and CG11. Although the varieties on the rootstocks B9 and CG11 fruited significantly more in 2019, they also fell into alternate bearing. Alternate bearing significantly influenced the proportion of class 1 fruit. For the further development of the trial, especially on these dwarfing rootstocks, it will therefore be crucial to prevent the alternate bearing through efficient mechanical thinning.