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POTENTIAL APPLE ROOTSTOCKS FOR VERMONT
(The information presented here has been gathered from various sources, our UVM NC-140 Rootstock Evaluation plot, and grower comments)
M. Elena Garcia
Tree Fruit Specialist
Seedling (adapted to various soil conditions)
Strong Points:
Well anchored
Hardy
Tolerant to fireblight
Very few burrknots
Large, vigorous tree
Weak Points:
Yield variable
Variable resistance to crown rot
Suckering may be a problem
MM.111 (best on well to moderate drained soils)
Strong Points:
80 to 85 % of seedling size
More tolerant of drought than other rootstocks
Resistant to WAA
Good anchorage
Moderately resistant to collar rot
Hardy
Spreading and rugged root system - can tolerate wider range of soil conditions
Weak Points:
Large trees perhaps only 10 to 15% smaller than seedling trees
Later fruiting than MM.106
Excessive burrknot development
Doe not tolerate wet soils
Tree form is more upright
MM.106 (best on well drained deep soils)
Strong Points:
Induces early bearing - more so than other semi dwarfing stocks.
Cultivars usually productive on this rootstock
Above average tolerance to drought and low temperatures
Good anchorage and favors good framework and central leader development
Sucker free
Resistant to WAA
Hardy very spreading - penetrating root system
Weak Points:
Susceptible to collar rot and tomato ring spot virus
Sensitive to "wet foot"
Resumes growth in the early spring and hardens off in late fall
Excessive vigor particularly on standard type Delicious that do not bear early
Dwarfing 70 to 85% of seedling tree development - too large
M.7 (best on well to moderate deep drained soils)
Strong Points:
Some dwarfing - 55 to 75% of seedling tree size
Commercially acceptable -was considered the standard planting stock
Early bearing
Above average resistance to collar rot
Above average tolerance to droughty soils
Major tap root with several branch spreading roots
Hardy, but not as hardy as M.26
Weak Points:
Severe suckering
Anchorage only fair - not recommended for Delicious and shallow soil plantings
Susceptible to WAA
G.30 (well adapted to most soils)
Strong Points:
60 to 65 % of seedling size
Early bearing and more productive than M.7a
Well anchored
Much less prone to suckering than M.7a
Resistant to fireblight
Weak Points:
More testing needed
May be more difficult to obtain. (Available in 1998)
Susceptible to common latent viruses
Brittle graft union with some newer cultivars
M.26 (best on well drained, loamy soils)
Strong Points:
55 to 65 % of seedling tree size
Easy to prune, maintain and harvest
Early bearing in some orchards
Very productive if properly spaced and trees vigorous
Hardiest of M or MM series rootstock
Little suckering
Spreading root system
Weak Points:
Susceptible to fire blight, WAA, collar rot and tomato ring spot virus
Suckers and excessive burrknots
Trees require support in many orchards
Variability in tree vigor
Some cultivars and spur-types on certain soils have displayed weak growth and crop performance, i.e., Cortland, Macspur and Spur Delicious - must plant on only the best well drained soils
Very sensitive to "wet feet"
Possibility of incompatibility at graft union with some cultivars, i.e.,Macoun
Somewhat slow to harden-off
M.9 (best on well drained, loamy soils)
Strong Points:
40 to 45 % of seedling tree size
Early bearing and capable of good yields
Resistant to collar rot
Valuable as interstock on interstem trees
Easy to prune, maintain and harvest
Well suited for trellising or training to a post
Small - confining root system
Weak Points:
Trees need support because of brittle root system
Bark attractive to mice
Suckers
Susceptible to fire blight and wooly apple aphids (WAA)
Bud. 9 (does not tolerate wet soils)
Strong Points:
Promising new rootstock
35 to 40 % size of seedling
Very resistant to collar rot
Hardier than M.9
Weak Points:
Needs support
Moderately susceptible to fireblight and tomato ringspot virus
Drought susceptible
P.2 (best in well drained soils)
Strong Points:
35 to 40 % size of seedling
Very early bearing
Resistant to crown rot
Very little suckering
Weak Points:
Needs support
Moderately susceptible to fireblight
Susceptible to tomato ringspot virus
M.27 (best on well drained, loamy soils)
Strong Points:
25 to 30 % of seedling size, or even smaller
Very dwarfing (4 to 5 feet ) and somewhat hardy
Very early bearing
Resistant to collar rot
Useful as interstock on interstem trees
Easy to prune, maintain and harvest
Smaller - confining root system
Weak Points:
Poor anchorage because of brittle root system - tree needs support
Susceptible to fire blight
Only suitable for vigorous growing cultivars
Easy to 'runt-out'
Ottawa 3 (well drained soils)
Strong Points:
50 to 55 % of seedling tree size
Early bearing
Very productive
As hardy as M.26
Resistant in most soils to crown rot
Very few burrknots
Weak points:
May need support
Roots poorly; may be a factor in orchard establishment
Moderately susceptible to tomato ringspot virus and common latent viruses
EMLA, 9, 26, 7 etc. (Virus - free)
Strong Points:
Cultivars on virus-free rootstock are more vigorous than those on virus-infected rootstock
Virus-free M.9's probably will produce larger yields than virus-infected trees
Yield efficiency (pounds of fruit/unit of space occupied) may be higher
Fruit quality may be better because they have stronger growth, may require less "tender loving care"
Interstems (Best on well drained, loamy soils)
M.27M.9/MM 106 (adapted to most soils)
Strong points:
50 to 60 seedling size
Early bearing
Productive
Moderate hardiness
Easy to prune, maintain and harvest
Spreading root system
Weak Points:
More expensive than single worked tree
Usually only available by contracting 2 years in advance of planting
Lack of data on long-term performance
On some cultivars and spur-type, it may be difficult to develop a strong central leader
Suckers from rootstock and interstem piece (especially when stem piece is planted above soil line)
The interstem piece is generally M.9
Burrknots* on the M.9 stempiece are common
Tendency to cause inconsistent tree development and crop performance
Posting usually required when interstem portion planted above soil line
Stem piece can often become distorted in form
M.27, M.9/MM.111 (good in most soils)
Strong points:
50 to 60 % of seedling tree size
Early bearing
Very productive
Moderately hardiness
Weak points:
Similar to the previous combination
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