fab,
I'm gonna be grafting scions of a southern live oak - Q.virginiana(maybe fusiformis) that has a 40+ yr history of survival here in KY - onto Q.macrocarpa understock in the next couple of weeks. Evergreen onto deciduous. I anticipate success.

I routinely stick interstems of OHxF 513 between seedling callery and various Euro & Asian pear varieties.

lucky,
Sounds pretty neat! So how did you know to try some of these pairings... is it all just trial and error or is there some literature out there worth reading first?

thanks

fn,
Some of both...
OHxF 513 is noted to be graft compatible with both Euro & Asian pears, without the dreaded 'pear decline' that occurs with some Asian on some P.communis rootstocks. Have a number of pears grafted on 513 - and lots of suckers. I figured an 8-10 inch interstem *might* work to inhibit size somewhat - below the 'standard' size trees a pure callery pear understock would likely produce - OHxF 513 is a 'semi-dwarfing' clonal rootstock selection.
I have a few varieties on callery without the interstem - too soon to tell what longterm comparisons will show, with regard to ultimate size and fruiting capacity.

Most members of the white oak group are fairly consistently graft-compatible. Q.macrocarpa seedlings are what I have most readily available, so I use it almost exclusively as an understock for members of the white oak group (Q.virginiana/fusiformis are in this group).