Friday, April 8, 2011

Rootstocks for Apple Trees

Dwarfing can be achieved by pruning rootstocks, 
or by limiting a needed resource. This tree is 
dwarfed by a lack of summer water.

Attaching a favorite fruit tree to an unrelated root has been a standard practice in growing apple trees for centuries. Besides being the easiest way to grow that favorite apple, rootstocks can also affect the way the tree or the fruit develops.

The most noticeable effect of a rootstock is the size of the tree it forms. Placing the same apple variety on different roots can create a tree anywhere from a normal 30 foot tree to a tree seven or eight feet tall.

This tendency to be smaller anywhere in the natural world is called dwarfing. Of course it doesn't matter how much smaller it is, even if it is only two percent smaller, it will be called a dwarf. For this reason, most pomologists and horticulturalists will use a term like 'semi dwarf' for the dwarfs that are closer to full size.

Dwarf fruit trees have become the standard in the orchard business because they are easier to pick, prune, and spray. The homeowner has the added benefit of having a fruit tree that doesn't take up most of his yard. And he may be able to fit in a few varieties instead of just one.

The following is a list of some of the more common rootstocks that you are likely to find:

Apple Seedling  
    Highly variable, but most often produces a full sized tree. 
    Low suckering.
    More tolerant of differing soils and water conditions.

MM 111  
    Best named rootstock for most conditions. 
    70% to 90% standard tree height, maybe taller. 
    Well anchored with a good root. 
    Tolerant of wet and dry soils.
    Low suckering. 
    Resists wooly aphid and collar rot.
    Susceptible to burr knots.

MM 106
    65% to 75% of full sized tree.
    Well anchored.
    Bears early.
    No root suckers.
    Fruit matures late in the season.
    Trees grow late in the year making them prone to winter damage.
    Crown and root rot susceptible.

M 27
    20% to 30% standard hight.
    Early and heavy fruit bearing.
    Good for pots and planters.
    Few suckers.
    Likes well drained soil, but constant moisture.
    Smaller than normal fruit.
    Small root system needs staking when young, maybe longer.

M 26
    40% to 50% of normal tree size.
    Few suckers.
    Collar rot resistant.
    Cold hardy.
    Early bearing.
    Needs staking.
    Needs regular irrigation.
    Susceptible to crown rot and fireblight.
    ELMA 26 is the same rootstock, but virus free. Reliable dealers will have all virus free stock no matter what the name.

M 9
    20% to 30% standard size.
    Increases fruit size.
    Ripening accelerated by one week.
    Does well in clay soil and wet conditions.
    Not drought tolerant.
    Susceptible to fireblight and wooly aphid.
    Shallow root system.
    Brittle roots require extra support.

M 7
    55% to 65% normal size.
    Early and heavy bearing.
    Resists fireblight, powdery mildew, and some collar rot.
    Winter hardy.
    Adaptable to many soils.
    Likes rooting deeply.
    Abundant suckers.
    Will usually need staking.

    25% to 35% normal height.
    Phytophthora and root rot resistant.
    Good anchorage.
    Few suckers.
    Heavy bearing, thinning is a must.
    Needs fertile soil and constant moisture.

    20% to 30% standard size.
    Similar to M 9.
    More winter hardy than M 9.

Geneva 30 (G 30)

    40% to 50% standard height.
    Similar to M 7.
    Good anchorage.
    High production.
    Weak grafts with some varieties of apples.
    Needs support.

Look for more of the Geneva series, as well as the Vineland, as the Cornell and Vineland programs becomes more widely known.

Also remember, that good, well informed pruning can bring any tree down even further with a little work.

Have a great time choosing this years apple trees

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