Table 9.1. Characteristics of Apple Rootstocks and Interstem Combinations, cont'd.
Prepared by Dr. Paul Domoto, Dept. of Horticulture, Iowa State University Extension(2/96)

RootstockSize¹FruitingHardinessCrown Rot

Fire

Blight

Remarks

Anchorage

M.9, M.9-T337
& other M.9
strains

Cornell-Geneva
16

Mark

Bud.9
(B.9)

Geneva 65

P.2

M.27,
EMLA 27

40-45%

40-45%

35-40%

35-40%

35-40%

35-40%

25-30%

Very early bearing,
very productive

Very early bearing,
very productive

Very early bearing,
very productive

Very early bearing,
very productive

Very early bearing,
very productive

Very early bearing,
very productive

Very early bearing,
very productive

Needs support

Very good, support
needed for crop

Roots are brittle,
needs support;
Drought susceptible

Needs support

Well anchored,
support needed for
crop

Needs support

Needs support

Slightly hardier than
M.7a.

Needs testing

Hardy early, but
susc. in late winter

Hardier than M.9

Needs testing

Needs further
testing

As hardy as M.7a

Resistant on
most soils

Tolerant

Resistant on
most soils

Very resistant

Resistant

Resistant

Resistant on
most soils

Very
susceptible

Very
resistant

Susceptible

Susceptible

Very
resistant

Moderately
susceptible

Susceptible

Suckers heavily; prone to burrknots

Very little suckering; no burrknots²
susceptible to common latent viruses
released soon, available 1998?

Prone to swelling, suckering; burrknots
ringspot virus³.

Promising new rootstock. Some suckering; very
few burrknots². Drought susceptible.
Susceptible to tomato ringspot virus

Promising new rootstock. Some suckering;
nearly no burrknots². Susceptible to apple stem
grooving virus⁴. Available 1999?

Very little suckering; few burrknots
Susceptible to tomato ringspot virus

Too dwarfing for standard orchards. Almost not
suckering, or burrknots². Susceptible to tomato
ringspot virus³.

1_{Size control as a percentage of the size of a cultivar on a seedling rootstock. Remember that the vigor of the scion cultivar also influences the ultimate size of the tree on any rootstock.}

2_{Burrknots are above ground root primordia that form under shaded conditions (either from a trunk wrap or excessive suckering). They are very sensitive to winter injury, and a potential point of entry for fire blight}
bacteria.

3_{Tomato ringspot virus is a nematode-transmitted virus that can induce Apple Union Necrosis and Decline disease when a sensitive cultivar is propagated on a sensitive rootstock. It has not yet been found in Iowa, but}
as a precaution, purchase virus-free trees. If the disease is ever found in your orchard, avoid combinations of a sensitive cultivar propagated on a sensitive rootstock. Cultivars sensitive to tomato ringspot virus
include: Red Delicious, McIntosh, Paulared, Spartan, Tydeman's Red, and Stayman.

4_{Virus problems can be greatly reduced by selecting virus-free cultivars.}

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