The great thing about Malus domestica rootstock is someone’s failed graft can become someone else’s prized rootstock seedling. This tree looks like a failed graft left in row some 100 years ago. These apples are the first full russet we have found. Thinking that Colorado Russet will be a fine name but we will DNA test first to be sure it does not match to an already named cultivar.
Choose rootstock type depending on availability:
Malus domestica Standard sized seedling rootstock. This is what trees were historically grafted on. These will be large trees that will grow for a century or more due to their cold hardiness and drought tolerance. Plant 25 feet or more apart.
M111 Semi Dwarf rootstock. 3/4 size of standard. A good compromise if you want a slightly smaller tree. Plant 15 feet or more apart.
M7 Semi Dwarf, Smaller than M111. Probably not as long lived, but produces sooner. Longer lived than M26. Plant 12 feet or more apart.
M26 Dwarf, Short lived (a few decades), fast producing, needs staked, not drought tolerant or as cold hardy, plant as close to 1-2 feet apart.