Characteristics of Apple Rootstocks and Interstem Combinations

 

Prepared by Paul Domoto, Dept. of Horticulture, Iowa State University, and Jim Cummins, Cornell University (retired).                                                                            (11/98)

      

 

Rootstock

 

Size1

 

Fruiting

 

Anchorage

 

Hardiness

Soil

Adaptability

Crown Rot

Fire Blight

 

Remarks

P.18

+100%

Slow bearing, moderate productivity

Well anchored

Considered hardy, more testing needed

Widely adapted

Very resistant

Moderately resistant

Very little suckering; very few burrknots2. May be susceptible to late winter freezes.

Seedling

100%

Slow bearing, yield variable

Well anchored

Hardy

Widely adapted

Variable

Tolerant

65-85% size control with spur-type Red Delicious strains; some size control with other spur-type strains. Suckering may be a problem; very few burrknots2.

Antonovka 313

100%

Slow bearing, moderate productivity

Well anchored

Considered hardy, more testing needed

Widely adapted

Resistant

Moderately susceptible

Some suckering; few burrknots2. Maybe susceptible to late winter freezes.

M.4

80-85% 

Moderately early bearing, good productivity

Well anchored, but subject to leaning

Moderate

Widely adapted

Resistant

Tolerant 

Most productive vigorous rootstock in regional testing.  Moderate to heavy suckering; few burrknots2.

MM.111

80-85%

Moderately slow bearing, medium productivity.

Well anchored

Moderate

Adapted to most soils; drought tolerant, but does not tolerate wet feet.

Tolerant on well drained soils.

Tolerant

Tree form is more up-right.  Little suckering; prone to burrknots2.  Semi-dwarf with spur-type Delicious strains. Moderately susceptible to tomato ringspot virus3.

MM.106

70-75%

Early bearing, productive

Good on most soils

Very susc. early, hardy late winter

Best in loam and sandy loam soils. Avoid poorly drained soils.

Very susceptible

Moderately susceptible

Very little suckering; prone to burrknots2. Very susceptible to tomato ringspot virus3.

B.490

70-75%

Early bearing, moderate productivity

Well anchored

Considered hardy; more testing needed

Well adapted to most soils

Moderately resistant

Tolerant

May be a replacement for MM.106. May be susceptible to late winter freezes. Almost no suckering; few burrknots2.

Cornell-Geneva 210

60-65%

Early bearing, productive

Anchored questionanble

Needs testing

Needs testing

Resistant

Resistant

Suckering may be a problem. May be released soon.

M.7a,

EMLA 7

60-65%

Early bearing, moderate productivity.

Free-standing but leans with some cultivars.

Moderate; roots tender, snow cover for best protection

Well adapted on most soils except heavy clay.

Slightly susc. on poorly drained soils.

Tolerant

Suckers heavily; somewhat prone to burrknots2.  Most widely adapted clonally propagated rootstock.

Geneva 30

 

60-65%

Earlier bearing & more productive than M.7a

Weak graft union  with some cultivars, support recommended.

Testing required

Well adapted to most soils

Tolerant

Resistant

Promising new rootstock. Much less prone to suckering than M.7a; burrknots2 rare. Susceptible to common latent viruses4. Available.

 

Rootstock

 

Size1

 

Fruiting

 

Anchorage

 

Hardiness

Soil

Adaptability

Crown Rot

Fire Blight

 

Remarks

M.26,

EMLA 26

55-60%

Very early bearing, productive

May need support in early years

Hardiest M. or MM. series rootstock;  somewhat slow to harden-off

Well drained soils

Moderately susceptible on poorly drained soils

Very

susceptible

Very little suckering; very prone to burrknots2. Susceptible to tomato ring-spot virus3. Compatibility problems have been identified with some cultivars.

Geneva 11

55-60%

Very early bearing, very productive

May need support in early years.

Testing required

Well adapted on most soils

Moderately resistant

Moderately resistant

Promising new rootstock. Little suckering; very few burrknots2.  Available 2001?

Ottawa 3

(O.3)

50-55%

Early bearing, very productive

May need support

As hardy as M.26

Well drained soils

Resistant on most soils

Susceptible

Roots poorly; may be a factor in orchard establishment. Moderate suckering; very few burrknots2. Moderately susceptible to tomato ringspot virus3 and common latent viruses4.

EMLA 9,

Pajam  2

45-50%

Very early bearing, very productive

Needs support

Slightly hardier than M.7a

Well drained soils

Resistant on most soils

Very susceptible

Suckers heavily; prone to burrknots2.

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

40-45%

Very early bearing, very productive

Needs support

Slightly hardier than M.7a.

Well drained soils

Resistant on most soils

Very susceptible

Suckers heavily; prone to burrknots2.

Geneva 16

 

45-50%

Very early bearing, very productive

Very good, support needed for crop

Needs testing

Needs testing

Tolerant

Very resistant

Very little suckering; no burrknots2. Very sensitive to common latent viruses4.  Released 1997.

Mark

35-40%

Very early bearing, very productive

Roots are brittle, needs support

Hardy early, but susc. in late winter

Best on well drained soils; drought susceptible

Resistant on most soils

Susceptible                      

Very prone to abnormal swelling of rootstock at ground line that stunts the trees. Moderate suckering; prone to burrknots2. Moderately susceptible to tomato ringspot virus3.

Bud.9

(B.9)

35-40%

Very early bearing, very productive

Needs support

Hardier than M.9

Well drained soils; does to not tolerate wet soils

Very resistant

Susceptible

Promising new rootstock. Some suckering; very few burrknots2. Drought susceptible. Susceptible to tomato ringspot virus3.  ISU observations suggest it is very susceptible to voles.

Geneva 65

 

35-40%

Very early bearing, very productive. Fruit size reduced.

Well anchored, support needed for crop

Hardy

Needs testing

Resistant

Very resistant

Promising new rootstock. Some suckering; nearly no burrknots2. Susceptible to apple stem grooving virus4. Available 2001?

P.2

35-40%

Very early bearing, very productive

Needs support

Needs further testing

Well drained soils

Resistant

Moderately susceptible

Very little suckering; few burrknots2. Susceptible to tomato ringspot virus3.

 

 Rootstock

 

Size1

 

Fruiting

 

Anchorage

 

Hardiness

Soil

Adaptability

Crown Rot

Fire Blight

 

Remarks

M.27,

EMLA 27

25-30%

Very early bearing, very productive. Fruit size reduced.

Needs support

Slow to harden-off

Well drained soils

Resistant on most soils

Susceptible

Too dwarfing for standard orchards; has potential for vigorous cultivars in very high density plantings. Almost not suckering, or burrknots2. Susceptible to tomato ringspot virus3.

P.22

25-30%

Very early bearing, productive

Needs support

Needs further testing

Well drained soils

Resistant

Moderately susceptible

Too dwarfing for standard orchards; has potential as a rootstock for vigorous cultivars in a very high density plantings. Very little suckering; very few burrknots2.

Interstem

    /

Rootstock

 

 

 

 

 

 

 

 

M.27, M.9

   /

 MM.106

50-60%5

Early bearing, productive

Good in most soils; may need support on light soils or when the interstem-rootstock graft union is above ground.

Slightly hardier with interstem-rootstock graft union below ground

Well drained soils; better adapted with interstem-rootstock graft union below ground

More tolerant with interstem-rootstock graft union below ground

Susceptible as M.27 or M.9

Suckering is a problem; can be reduced by planting interstem-rootstock graft union below ground. Additional cost.

M.27, M.9

   /

 MM.111

50-60%5

Early bearing, productive

Good in most soils; may need support on light soils or when the interstem-rootstock graft union is above ground

Moderate

Widely adapted to most soils

Tolerant on most soils

Susceptible as M.27 or M.9

Suckering is a problem; can be reduced by planting interstem-rootstock graft union below ground. Additional cost.

 

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.

 

5        Used as interstems, M.27 and M.9 produce similar sized trees.  With the present propagation practice of using 6- to 8-inch interstem sections, relative tree size is more dependent upon planting depth: With the interstem-rootstock graft union above the ground, tree size is between M.9 and M.26; with the interstem-rootstock graft union below the ground, tree size is between M.26 and M.7a and depends upon how much of the interstem is exposed.