APPLE ROOTSTOCKS
O.3

SIZE CLASS 4

Ottawa 3



Pedigree

'Robin' (hardy crab) X M.9

 

Precocity

Similar to M.26

Productivity

Very productive, similar to M.26

Scion Fruit Size

Comparable to M.26
Scion Fruit Quality Good, high coloring

Anchorage

Support usually recommended, but anchorage is better than M.9, similar to M.26

Fire blight

Susceptible

Crown & Root Rots

Reportedly resistant, further testing required

Woolly Apple Aphid

Susceptible

Powdery Mildew

Susceptible

Hardiness (Midwinter)

Originally released as a more cold tolerant competitor to M.26, later tests have been inconclusive. O.3 is probably among the most cold tolerant rootstock genotypes, but perhaps not in late winter/early spring.
Bud Break  
Leaf Fall  

Suckering

Light

Burrknots

Light

Stoolbed Performance

Very difficult

Virus hypersensitivities

Apple stem grooving virus, Tomato Ringspot Virus

Experience

O.3 has been planted in North America on a moderate scale.

Sources

Cummins, Meadow Lake

Strains

 

Observations, suspicions, history

O.3 is a promising cold hardy rootstock for growers interested in a rootstock generally considered intermediate between M.9 and M.26 in vigor. Lack of resistance to fire blight decreases the utility of this genotype. Because O.3 is difficult to propagate in the stoolbed there are few nurseries willing to supply it. Virus indexed scionwood is strongly recommeded whenever propagating O.3 nursery trees.

 

 

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Last modified September 21, 1999.