As I recall, it's too cold tender for Z5 and extremely vigorous.

Thanks H-man. I recall the commercial ornamental cultivars but have no rootstock application experience.

I have all my pears on this stock both euro and asian. But have never used any of OF series They all do fine and the stock is extremely fire blight resistant which is why I use it. but not very cold hardy only to about 0 to -10.

Now that "Cleveland" ornamental pears are replacing "Bradford" there is cross-pollination and abundant fruiting (and pestiferous forset invasion) of these callery pears. I have collected seeds and will try seedlings in a year or so as rootstock.

Interesting, GB.

The seedlings in some areas around me are becoming an invasive pest. I dug some last year and grafted several European and Asian to them. They took and grew well, but on how they would compare to other rootstocks I don't know yet.

I use callery seedlings, with an 8-10 inch interstem of OHxF 513 - compatible, long-term, with both Euro and Asian pears, fireblight-resistant, and will provide a moderate degree of dwarfing(makes a semi-dwarf tree, maybe 65-75% of standard).

Is there an inherent advantage over simply using OHxF 513 rootstock?

I have plenty of callery seedlings, free for the digging and grafting, courtesy of the birds and all the various callery pears in residential plantings. Have some pears on 513 that are constantly suckering from the rootstock.
Initially did the interstem deal just for grins - but Dr. Natelson indicated that 513 does work well as an interstem to reduce size somewhat - and it is reliably compatible with Euro and Asian pears.
So...it was cheaper to do than purchasing more 513 from a nursery - I've tried rooting cuttings of it with no success(but I didn't put much effort into it, either), and could, I guess start a stooling mound - but I haven't.

I put the interstem and fruiting scion together, then grafted the combo unit onto understock - both unions callused rapidly and the fruiting scion grew just as well as any grafted directly onto the callery understock.

Thanks.

I may start to do the exact same. I might leave a small 513 clipped annually as if for stooling but really just growing interstem pieces. I have one left over that can easily be put to that purpose and it's in a small put so it won't be too vigorous.

I still need to airlayer the OHxF 51 I obtained from USDA to try it as rootstock too.