Supporter® 4 was bred at the Pillnitz Research Station near Dresden, Germany, in 1921 as a cross of M-9 and M-4. Little was known about it until after the fall of the Berlin Wall but it had been tested extensively in Eastern Europe.
Influence on Scion Habit
Tree vigor is somewhere between M-26 and M-7. Supporter® 4 has excellent fruit production with precocity somewhere between M-26 and M-9.
Supporter® 4 has low sensitivity to collar rot. It is sensitive to fire blight and rated between M-9 and M-26 in sensitivity.
Supporter® 4 roots very well in layer beds. It has a compact growth with little tendency for suckering.
Trees on Supporter® 4 are more uniform than those on M-26 with little burr knotting and overgrowth. This rootstock is ideal for low-vigor or replant sites and low-vigor varieties.