Updated, Monday, March 17, 2014
The vast majority of fruit trees we grow consist of two trees-in-one – a fruit variety such as Gravenstein apple or Bing cherry, grafted on to a rootstock variety. The part of the tree above the graft union is known as the scion and the part below the graft union is known as the rootstock. Rootstocks determine several qualities of the fruit tree which sits above it, the most important of which is size. A super-dwarfing apple rootstock will produce an apple tree about 6′ high, for example, whereas a ‘standard sized’ rootstock can produce an apple tree 25′ high.
Generally, rootstock is the primary factor determining tree height, though other factors play a role – the vigor of the variety grafted on the rootstock, soil fertility, climate and irrigation practices. Pruning also has a great impact on size. When the tree has reached the height that you want, the easiest, most effective way to keep trees at that height is through summer pruning. Here’s how to guesstimate spacing between your fruit trees.
Here are the mainstay rootstockvarieties we will have available at the 2014 propagation fair, with a smaller selection of other rootstock varieties available to meet specific requirements.
Super-Dwarfing Apple Rootstock
Mature height about 5-6ft. An excellent rootstock for the enthusiast who wants to plant a lot of apple varieties in a small space – performs very well provided attention is paid to soil and watering. Begins fruiting within 2-3 years. Plant 4′ apart. Ideal for small spaces, container planting, hedging. Young trees need staking.
Dwarfing Apple Rootstock
M-9 (NAKB 9 337)
Mature height 9-12 ft. M9 is probably the most widely-planted of all rootstocks, and the mainstay of commercial apple production. M-9 dwarfs apple trees to 40 to 45% of seedling size, is very precocious and increases fruit size. Apple trees on M9 are very productive and come into bearing within 2-3 years of planting. The tree reaches full size after about 5 years. M9 is an excellent choice for the smaller garden or community orchard, especially those with heavy soils where drainage is adequate.
Mature height 9-12 ft. An excellent alternative to M9, with very similar characteristics. Bud-9 is extremely winter hardy and more tolerant to fire blight than M-9. Though fire blight is not yet a major concern for us locally, fruit geeks are witnessing it beginning to creep in. We anticipate the drift of climate change will worsen the problem. Use Bud-9 with varieties highly susceptible to fire-blight.
Mature height 10-13 ft. The advantage of this rootstock is an early, heavy production of quality fruit. Generally it is free standing (does not require staking) but with heavy fruit set can lean in very windy areas. Good in areas with frequent spring freezes, due to its delay in spring bud development. It has little tolerance of heavy, excessively acid, or unusually wet or dry soils.
Semi-dwarfing Apple rootstock
Mature height 12-16ft. One of the most desirable rootstocks when factors such as production efficiency, longevity, ease of propagation, hardiness, compatibility and disease resistance are considered. It has exceptional winter hardiness and good anchorage, but may require staking while young if in an open, windy area. It does well in most soils, especially deep, fertile soil versus light sandy or heavy clay. Good for high lead arsenic residue soils and old orchard sites with replant problems.
Semi-standard Apple Rootstock
Mature Height 18-22ft. with recommended 16-26ft. spacing. Excellent anchorage, with no staking required. Very drought tolerant and adapts to sandy and clay loam. Best Semi-Dwarf for heavy or poorly drained soils. Produces an early and prolific fruit crop.
Semi-Dwarfing Pear Rootstocks
Mature height 12-18 ft. In very recent years, Old Home Farmingdale 87 has emerged as the favored semi-dwarfing rootstock of choice among knowledgeable pear growers. The OHxF selections are compatible with most pear varieties and are known for their tolerance to blight and decline, and produce precocious (early-to-bear), well-anchored, very productive trees. Not vigorous enough for Asian Pears.
Mature height 15-20 ft. Resistant to fire blight, collar rot, woolly pear aphids and pear decline. Precocious, well-anchored, very productive trees. Does not sucker. Does well on a variety of soils.
Mature height 20-28 ft for European pears, 15-20 ft Asian pears. Produces European pear trees 95%-1005 of standard, but more precocious and productive than grown on seedlings. Produces precocious, well-anchored, very productive trees.Appears to be especially valuable for Asian pears.
Mature height of 15 – 18 ft. Asian pears require a more vigorous rootstock than European pears. For Asian pears only, we use Pyrus betulaefolia or ‘Betch’ which is very vigorous, tolerates wet soil, dry soil, and alkaline soil, and resists pear decline. ‘Betch’ is widely used as an Asian pear rootstock because it is long-lived, versatile, vigorous, and it tends to produce abundant crops and large fruits.
Dwarfing and Semi-dwarfing Stone Fruit Rootstocks
(Plum, Prune, Apricot, Peach, Nectarine, Almond)
Slightly dwarfing. 10-14 ft. A new dwarfing rootstock for plum trees, developed in Russia and released in 2004. The main disadvantage of Krymsk 1 is that there is relatively little experience of its performance outside of research stations, though it offers the potential to produce a smaller plum tree than what has hitherto been available.
St. Julian ‘A”
Slightly dwarfing. Plums, peaches and nectarines from 12-15ft. St. Julian is compatible with all varieties of Prunus trees. Drought tolerant, it will tolerate a wide variety of soils. Very productive and well-anchored it has a highly-regarded, popular, well-proven history in Oregon.
Standard Cherry Rootstock
Mazzard is especially suited for sweet cherry and tart cherry planted in wet and heavy soil types. Especially well anchored. Mazzard, the most popular cherry rootstock grown in America, is widely used through the PNW. 20-25′.
Semi-dwarfing Persimmon rootstock
Persimmon rootstock with a mature height of 12-15 ft. Experience strongly suggests that grafting onto Dyospyros without settling the plant into ground for a year prove almost universally unsuccessful, whereas grafting to rootstock that has been a year in the ground proves largely successful. Pick up Dyospyros now for grafting next spring.