The majority of commercial pear trees are grown on rootstocks. Pear rootstocks impart characteristics such as vigor, precocity, disease resistance, and cold hardiness. The most commonly used rootstock worldwide is some selection of a Bartlett seedling, making it the “standard” rootstock. In rootstock trials, rootstock test scores are often expressed as a comparison to Bartlett characteristics. For example, the test rootstock may impart dwarf characteristics as 70% height compared to a Bartlett seedling tree. In North America, the most common Bartlett-type rootstock is OHxF. OH stands for “Old Home”, a name given to a seedling selection discovered in Illinois by Prof. F.E. Reimer of OSU. It was found to be resistant to fireblight, but was self-infertile. The “F” stands for Farmingdale, the town in Illinois that Reimer discovered the second Bartlett selection. Like OH, it had fireblight resistance, although not quite as good, but it was self-fertile. Old Home and Farmingdale were crossed by L. Brooks of Oregon and the resulting offspring were fireblight resistant, self-fertile, vigorous and had good cold hardiness, making it desirable as a rootstock and receiving a patent in 1960.
The graphic above illustrates the overall influence on tree size* by various rootstock combinations compared to a Pyrus pear seedling. Key to abbreviations and names: BM = P. communis series from Australia; Brossier = P. nivalis series from Angers, France; Fox = P. communis series from the University of Bologna in Italy; Horner = OHxF clonal series from D. Horner (Oregon nurseryman) and selections by OSU-MCAREC; OHxF = ‘Old Home x Farmingdale’ series; Pi-BU = Pyrus series from Germany; Pyro and Pyrodwarf = P. communis selections from Germany; QR = P. communis selections; ‘Adams’, ‘BA29’, ‘EMC’, ‘EMH’, ‘Sydo’ = Quince dwarfing rootstocks (require interstem for most pear cultivars).
Selections shown in gray text indicate antiquated selections no longer in commercial production.
Selections shown in purple text indicate possible susceptibility to pear decline.
*This general classification of tree size may vary for different cultivars due to cultivar/rootstock interactions.
This graphic was adapted from the article by Elkins, Bell, Einhorn, 2012, J. Amer. Pomol. Soc. 66(3):153-163.
Pear varieties growing on OHxF or any Bartlett seedling rootstock tend to be large, non-porous trees. In order to get trees that are more suited to high-density plantings, rootstocks with dwarfing traits and precocity need to be used. In many parts of the world Quince selections are used as rootstocks. This combination will result in dwarfed growth and precocity. However, Quince is not compatible as a rootstock for many varieties of pear such as Bartlett, Bosc, Forelle, Packham, Triumph, Winter Nellis and Eldorado. For these varieties, the use of an interstock (intermediate graft section) must be used. Another problem with using Quince is that most varieties are not winter hardy making it a poor choice for the Pacfic Northwest. However, there are ongoing trials at OSU testing potential Quince selections exhibiting good winter hardiness (Einhorn’s work).
Descriptions of some of the more commonly available pear rootstock.
Bartlett Seedling (Domestic French)
Hardy seedling rootstock Van Well Nursery uses for pear and Asian pear varieties. Source: VanWell Nursery
Old Home x Farmingdale
‘Old Home’ by ‘Farmingdale’ (OHxF) rootstocks, are a trademark of Carlton Plants. The OHxF series of rootstocks originated from crosses made more than 75 years ago by Reimer at Oregon State University. Reimer was looking primarily for rootstocks resistant to fireblight. Both parents are highly resistant. The work was further developed by Lyle Brooks of Daybreak Nursery and Dr. Mel Westwood at Oregon State University. This superior series of rootstocks are well-anchored and compatible with most varieties. Also, they are winter hardy, precocious and quite productive. Source: Cummins Nursery.
A semi-vigorous pear rootstock, about 2/3 standard size. Resistant to fire blight, crown rot, woolly pear aphids, and pear decline. Precocious, well-anchored. Patented with a 50¢ royalty fee. OFxF40 is not very precocious and is not recommended to use with Bosc, which would result in fewer and small fruit. (T. Auvil, WTFRC
) Source: Cummins Nursery.
OHxF 87™ (Brooks Selection, USPP#6392)
OHxF 87™ makes a tree slightly smaller than Bartlett on seedling root. It is considered a semi-dwarf tree. OHxF 87™ is one of the best producing rootstocks of the OHxF series and was selected for this reason. The OHxF selections are compatible with most pear varieties and are known for their tolerance to blight and decline. Research from Oregon shows OHxF 87™ is an excellent producer. OHxF 87 should be planted 6-8′ between trees within a row. It gives early vigor and is more precocious that OHxF 97. It is also best when paired with a vigorous variety such as Anjou. It is not good for interplanting with less vigorous trees due to competition for light. As a patented selection, OHxF 87™ is available only through selected outlets. Van Well offers this rootstock through a licensing agreement with Carlton Plants, Inc. Source: VanWell Nursery with additional comments by T. Auvil, WFTRC
A clonal rootstock of ‘Old Home’ x ‘Farmingdale’, this rootstock is resistant to pear decline and fireblight. It is a superior rootstock for vigorous pear trees. Hardy and resilient to cold. It provides good anchoring and yield efficiency. It is bet planted 8-12′ between trees within a row. OHXF 97 is less precocious than OHxF 87. Source: VanWell Nursery with additional comments by T. Auvil, WFTRC
A semi-dwarfing pear rootstock. It is 1/2 to 2/3 standard size. Its resistance to fireblight, collar rot, woolly pear aphids and pear decline make this a very healthy stock. it is not very precocious and gives few fruit and with reduced size (T. Auvil, WTFRC). Source: Cummins Nursery
PyroDwarf produces a tree 61% – 70% of the size of a seedling pear tree. It is an alternative to seedling rootstocks, as it produces large attractive trees which start bearing usually after 3-4 years. Being of Pyrus
origin, there are no graft incompatibility issues with this rootstock. PyroDwarf is able to tolerate chalk / alkaline soils better than quince-derived rootstocks. PyroDwarf was developed from a cross between ‘Old Home’ (fireblight resistance) and ‘Louise Bonne dAvranches’ (ability to strike hardwood cuttings) pear varieties made by Helmut Jacob, at the Research Institute and College, Geisenheim, Germany, but has only inherited some of the ‘Old Homes’ fireblight resistance. However, it has been reported that this variety produces severe suckering with spiny shoots, as well as causing reduced fruit number (T. Auvil, WTFRC). Source: orangepippinstrees.com.