Quince rootstocks are used to produce dwarfing or semi-dwarfing pear trees. This is not ideal as the use of a different closely related species always introduces a certain amount of incompatibility. The extent of incompatibility varies with variety. In the case of varieties which are very incompatible double grafting which involves inserting a section of a compatible pear between the scion and rootstock needs to be used. Quince rootstocks also suffer from an inability to tolerate chalky or alkali soils. Two of the original quince rootstocks selected at East Malling Research Station Malling Quince C (QC - dwarfing) and Malling Quince A (QA – semi-dwarfing) are still the most widely used rootstocks for pear trees. Variations on these such as BA29, Quince EMH and Quince Eline have been developed and are also used to some extent.
There has been very limited success to date in producing a dwarfing or even semi-dwarfing pear rootstock. The problem has mainly been that the pear rootstocks which have been developed have proved difficult to propagate commercially. Seedling pear produces very vigorous trees. Random or selected seedlings such as Pyrus Kirchesaller are used for large standard trees. The only clonal pear rootstock currently available is Pyrodwarf which despite its name is a semi-vigorous to vigorous rootstock. Pyrodwarf has to be produced by tissue culture. It is particularly useful for varieties of pear which have poor compatibility with quince rootstocks. Pear rootstocks are also useful for growing pear trees on chalky or alkali soils on which quince rootstocks do not thrive.
Quince rootstocks are also used for quince and medlar trees. We have not found pear rootstocks to be particularly successful for quince trees. We also use quince and also pear rootstocks for medlar trees. Hawthorn (Crataegus) rootstocks are commonly used for medlar but we no longer use them because they tend to sucker heavily. Subject to availability we also use seedling medlar (Mespilus) for medlars in order to achieve the best possible compatibility.
We currently use Quince C (dwarfing), Quince A (semi-dwarfing), Pyrodwarf (semi-vigorous), Pyrus seedling pear (very vigorous) for pear trees.