Pear Rootstocks
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To ensure abundant cropping, it is crucial to have a well-developed and strong root system insuring good annual growth, distribution and absorption of the nutrients present in the water solution within the soil. Long ago, growers and researchers have noticed that there is a relationship between the overall tree performance and the rootstock it was grafted on. What started as casual observation, received validation through the research. Rootstocks influence tree’s ability to survive cold temperatures (winter hardiness), tree size, mineral absorption, tolerance to different soil conditions, anchoring, yield capacity, flowering, fruit size, mineral composition of the fruit and fruit quality.
Commonly, rootstocks for pears are pear seedlings. Typically, those trees show good cold hardiness, and productivity. Europeans use quince (Cydonia oblonga) as a rootstock to control size and to overcome shortcomings of a heavy, wet soils. In the U.S. quince as a rootstock is not part of recommendation because it is sensitive to cold.
Bartlett Seedling (Pyrus communis)
Bartlett seedlings is an industry standard.
Produces very vigorous, large trees (100%).
Trees are very productive.
Winter hardy.
Their negative trait is greater variability in tree size due to natural genetic variability of Bartlett seedlings. To provide more of a uniform growth size, selections from Old Home x Farmingdale breeding combinations are replacing the pear seedlings as rootstocks.
OH x F 97
- This is a hybrid between Old Home and Farmingdale pears.
- Produces vigorous, large trees similar in size to the ones on Bartlett seedlings.
- Provides greater uniformity in tree size than Bartlett seedlings.
- Winter hardy.
- Good productivity.
- Good root system insuring good anchoring.
- Resistant to fire blight (Erwinia amylovora).
- Good for Asian pears.
OH x F 87
- Produces slightly smaller trees, about 85-90% of standard.
- It is the most precocious of all Old Home x Farmingdale selections. Fruiting spurs develop early.
- Winter hardy.
- It has a good root system that anchors well.
- Does not sucker.
- Resistant to fire blight (Erwinia amylovora).
OH x F 333
- Produces trees that are only 50-70% of standard.
- It is suitable for semi-dwarf to dwarf plantings. It replaces quince since it is much more winter hardy.
- It is productive.
- It has good tolerance to diverse types of soils.
- It has good anchorage.
- It is resistant to fire blight (Erwinia amylovora), collar rot (Phytopthora spp.) and woolly aphids (Eriosoma lanigerum).
Pyrodwarf
Pyrodwarf, Pyro series come from a German breeding program. It is a cross between Old Home (fire blight resistance) and Bonne Louise d’Avranches (propagated by hardwood cuttings).
- Trees are 40-50% of standard and similar in size to trees on Provence Quince BA-29C.
- Very precocious, starts bearing in the second to third year after planting.
- High productivity and good uniform size fruit.
- Winter hardy.
- Highly tolerant to fire blight (Erwinia amylovora).
- Adopted to wide range of soils.
- Does not sucker.
Pyro 222
- Moderately vigorous trees. It reaches 70-80% of standard.
- It is suitable for semi-dwarf density plantings.
- Trees are precocious and productive.
- Tolerates wide range of soils.
Betulafolia (Pyrus betulafolia)
- This rootstock is strong, vigorous and standard-sized rootstock.
- Tolerates heavy, wet soils.
- It is less winter hardy than other pear rootstocks.
- Suitable for Asian pears.
- It has good tolerance to fire blight (Erwinia amylovora).
- Shows good tolerance to crown gall (Agrobacterium tumefaciens).
Quince (Cydonia oblonga)
- It is adoptive to various soils and tolerates heavier soils.
- It has moderately vigorous growth, about 55% of standard.
- It is precocious.
- Resistant to crown gall (Phytopthora spp.), pear decline and nematodes.
Figure 1. Pear rootstocks and their relative size compared to the Bartlett seedling (industry standard).
Author: Mira Bulatovic-Danilovich, WVU Extension Specialist – Consumer Horticulture