North American Fruit Explorers mailing list at ibiblio

[Mauch1@aol.com]

You might want to check out the Penn State Tree Fruit 
Production Guide online (http://tfpg.cas.psu.edu/).  One
system (French Axe) that seems to be gaining popularity, 
is using M9 and growing them to be 10-14 ft. tall.  (M9 in
general, also Bud 9, P2, and G16).  For Spur or weak growing 
types, M26 or G30).

Also there can be a huge variation in size depending on 
cultivar - in the NE variety trial in PA on M9 Enterprise
grew 176% of standard (standard was G. Delicious on M9), and
HoneyCrisp grew 57% of standard.  These were the widest 
variations.  So if you can determine vigor of a variety
you might want to try to "match" it to the right rootstock.

Chris Mauchline 
SE PA, zone 6