What is the difference between dwarf, semi-dwarf, and full/standard-size rootstock?
The primary difference between the different rootstocks is size. Generally, dwarf trees will reach up to 50% of the height of a full-size tree and semi-dwarf trees will reach up to 75% of that height. In regards to apples, for example, dwarf trees generally reach 8-10ft, semi-dwarf trees 12-15ft, and full-size trees 15-20ft.
We graft fruit trees to control vigor, size, and disease resistance. The variety grafted on top will work with the variety of rootstock below to create a unique size based on the vigor of the combination of the top and bottom, but we can roughly quantify the sizes by three main types: dwarf (small), semi-dwarf (medium), and full size (large).
Each type has pros and cons, and within each type of rootstock there are variations which are briefly described below. For general purpose orchards, we recommend sticking with semi-dwarf trees if you have the space.
A brief overview of the rootstocks we grow with:
M9: dwarf, hardy to zone 4, popular rootstock in large scale orchards but v. susceptible to fireblight. Requires permanent staking, suitable for espalier.
B9: dwarf, v. cold hardy, resistant to fireblight and collar rot, precocious, minimal suckering, good graft compatibility. Suitable for espalier. Requires permanent staking.
Ottawa 3: dwarf, v. cold hardy, vigorous, resistant to collar rot, susceptible to fireblight. Suitable for espalier. Requires permanent staking.
Emla 26: large dwarf/small semi-dwarf. Very precocious, suitable for espalier, popular in Southern ON, but not particularly cold hardy. Resistant to collar rot, but susceptible to fireblight. Doesn’t require permanent staking on sheltered sites.
Emla 106: semi-dwarf, nice balance of vigor and production, some susceptibility to moisture/collar rot, generally well suited to most soil types, well-anchored, hardy to zone 4. Our go-to rootstock.
Emla 7: small semi-dwarf, poor anchoring, well adapted to different soil, fireblight resistant.
Emla 111: large semi-dwarf, well anchored, adaptable to different soils.
B118: large semi-dwarf, v. cold hardy and vigorous, moderate resistance to crown rot and fireblight, poor graft compatibility.
Antonovka: full size, v. vigorous, the standard seedling rootstock, used in Russia for over 500 years. Due to its uncanny ability to stay very close to true when propagated by seed it produces a strong, deep root system (creating a drought tolerant, hardy tree).