Precocity of flowering is greatly influenced by choice of rootstock or interstock. Irrespective of the vigour of tree desired, the apple grower should always choose the rootstock, or rootstock/interstock combination, which is likely to induce precocious cropping.
- Trees grafted onto most of the dwarfing rootstocks currently available begin flowering more quickly following planting than trees raised on most of the more invigorating rootstocks.
- However, the semi-vigorous rootstocks MM.106, and M.116 (AR 86-1-25) and the vigorous rootstock M.25 are exceptions to this rule.
- All three of these rootstocks induce much better precocity in scions than most other rootstocks in the same vigour categories.
Dwarfing apple rootstocks that induce good floral precocity
| Super dwarfing | Dwarfing | Semi-dwarfing | Semi-vigorous | Vigorous |
|---|---|---|---|---|
| M.27 | M.8 | M26 | MM.106 | M.25 |
| M.20 | M.9* | Mark | M.116 | |
| J-TE-G | Ottawa 3 | P.14 | ||
| P.22 | P.2 | Bud 9 | ||
| P.16 | J-TE-E |
- Increasing the height above ground level of budding apple scions onto dwarfing rootstocks increases the dwarfing effect on the scion and may also increase precocity of flowering.
- Using a dwarfing rootstock as an interstock, between the scion and a more invigorating rootstock, dwarfs trees more than if trees were raised directly on the invigorating rootstock.
- These interstocks also improve precocity of flowering.
- Increasing the length of interstock used, up to 25 or 30cm, also increases the effects on scion dwarfing and precocity.
Dutch research has shown that use of other scion varieties as interstems (between the rootstock and the main scion variety) can also improve precocity of flowering.
- Interstems, of the varieties Golden Delicious or Zoet Aagt, have both induced such benefits in scions.
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| Rootstocks bred at NIAB East Malling |