North American Fruit Explorers mailing list at ibiblio

["tanis cuff" <tanistanis@hotmail.com>]

Found a long list of pear research articles at

http://www.actahort.org/books/596/index.htm

Listed articles are in PDF form, and some are huge.

Pyrodwarf info may be at   .../books/596/596_52.htm
("New Pear Rootstocks from Geisenheim)

I found a few other titles by searching "Pyrodwarf" in the ISHS internal 
search-engine.

Another useful article might be at yahoo-search of
Pear Rootstock & Cultivar Research at the OSU Mid-Columbia Agricultural 
Research & Extension Center [might have to use 'and' instaed of '&']

I'm sorry I can't report on these, but I don't know when I'll have access to 
a computer which can handle them.  Good luck/ have fun.