I have (apparently) successfully grafted several Biscamp, Perdue, and Southern Bartlett onto both P. calleryana (Bradford Pear - walmart $10) and P. betulafolia (Burnt Ridge $2.50) rootstock.

Both rootstock have good fireblight resistant, but since the grafts are so low to the ground, and since fireblight infections, I've read, arise in the fresh growing tips, I'm not sure that's really relevant.

The Bradfords are going to get a jump start, since they came as 7ft tall trees with one inch trunks, and the betulafolia were 1yr seedlings.  On the Bradfords, I cut the old scion (Cleveland Select) off entirely, and grafted to what is, I presume, a generic Bradford seedling that had been previously used as rootstock.

I am in South LA, with heavy clay soil, and will be planting up against a new wall with a 2ft deep/wide foundation, so likely somewhat alkaline.  Texas A&M recommends betufolia for heavier, less acidic soil, but the Bradfords grow around here pretty vigorously.  I have one in my yard that is nearly as big around as a fifty gallon drum!  (I'll be grafting onto it for fun next year)

I intend to espalier them along an 8ft wall with 12-13ft wide runs between pillars, so one tree will be planted in the middle of each run/span.  I hope for a formal pattern with 5-6 pairs of horizontal cordons on each side, about 6 feet long each.  Many of the cordons will be grafted scions from yet other good Southern varieties.

I have lived long enough now to take the long view, and earlier fruiting is only a secondary concern.  I really wonder about 5-10yrs from now, working to keep the trees confined to the space allotted. 

I've also read conflicting reports on whether betufolia is best reserved for Asian (vs. European, what I have) pears

Does anyone have any thoughts on which rootstock should go in the ground?

Thanks

The wild thorny pears that are becoming quite invasive are the same as Bradford rootstock. While on a fruit tree tour with Dr. Powell at Petals From the Past, I asked if I could graft to the wild pears.  He pointed to their large asian pears and said that is what we use (Calleryana).   Height and width should be a manner of how the tree is trained and pruned or even more aggressive measures like girdling.  As an aside, he said he would never even consider trying to control a standard size apple tree as an espalier.  

thanks bama.  (Geaux Tigers!!)

I think both of these rootstock are destined to be vigorous growers, and though aggressive pruning and training may tame them, it is likely to be a full-time job!

A reply on a local forum suggested "Old home x Farmingdale 333" rootstock, another fireblight resistant rootstock, but with 50-75% dwarfing.  I am going to order some and have at it. 

The others will be gifted away.

This is not neccessarily the final word, so any additional insight I welcome.