Apple Rootstocks

Intro Start-up Varieties Floor Management

Rootstocks- various dwarfing rootstocks are used for commercial apple trees. Dwarf rootstocks cause trees to be more compact, manageable and bear fruit at a younger age. Decisions on tree spacing and trellising are based largely on the degree of dwarfing caused by the rootstock. Primarily as a means of combating a soil-borne insect pest, wooly apple aphid, a series of rootstocks have been developed that impart varying degrees of dwarfing to apple trees. The advantages of dwarfing stocks are that they are much more space efficient, dwarfing stocks tend to come into production much earlier than standard size trees, and that fruit can be easily harvested.

Rootstock/Variety Size Remarks

EM 7 50% Virus-free stock adapted to heavy soils. Trees are moderately well anchored. May be short-lived in the South. Suckers considerably.

EM 9 30% to 40% Adapted to heavy soils and typically the varieties propagated on this stock bear early and bear high-quality fruit. Roots, however, are brittle and the trees must be staked. Some resistance to collar rot; also used as an interstem. Fire blight may take it out, even as an interstem in some areas.

EM 26 40 % Produces good quality fruit on trees that are better anchored than on EM 9; however it is more susceptible to collar rot and trees still need support on most sites.

MM 106 60 % Well anchored, no staking required, but susceptible to collar rot. Resistant to Wooly Apple Aphid. Often recommended with a dwarfing interstem.

MM 111 75 % Better adapted to heavy soils and resistant to collar rot. Also used with an interstem and for spur-type varieties. One of the most promising rootstocks for the southern growers. Resistant to the Wooly Apple Aphid.

* Inserted from Growing Fruits and Nuts In the South by William D. Adams and Thomas R. Leroy

Extremely dwarfing stocks such as EM 26 and M9 require a support structure such as a trellis because of shallow rooting characteristics. In areas where space is limited, the expense of a small trellis may be justified when including apples in a home planting.

For the most part, MM106, an intermediate dwarfing stock should be avoided because of susceptibility to an additional soil-borne fungal pathogen, Phytopthora cinnimoni , or Collar Rot.

Rootstocks that are somewhat dwarfing such as M7 or MM111 are more efficient and precocious than standard seedling stock and do not need a support system. For these reasons, these two stocks are common among both commercial and home plantings.

Trellising- Numerous younger Hill Country apple orchards are trellised, but trellising is an option, not a necessity. Trellis support is needed for severely dwarfing rootstocks like M 9 because of shallow, brittle, poorly anchored root systems. Trees on less dwarfing rootstocks such as MM 111, M 7 and MM 106 are best grown freestanding.

http://aggie-horticulture.tamu.edu/hillcountry/