Thanks for everyone's recommendations both public and
private. I ended up ordering 10 (minimum order quantity)
Mariana GF 8-1 (supposedly a very vigorous rootstock but
highly compatible with Apricot and Plum) from Cummins
Nursery.
Thanks,
--
Chris Mauchline
SE PA, zone 6
40° 5' N 75° 51'W
~650 ft elevation
<Maybe try Cummins Nursery?
18 Glass Factory Bay Rd.
Geneva NY 14456
315-789-7083
www.cumminsnursery.com
I don't know what they have in stock, this time of year; and the website
doesn't list either of those two varieties; but they might have
something you could use.