North American Fruit Explorers mailing list at ibiblio

["Dr. Ethan Natelson" <natelson@pipeline.com>]

Dear Group,

     To add to the comments of Anton, Chris, Kevin and Fluffy, one of the
problems in commenting about OH x F pear rootstock is that most of the
trials on these crosses seem to have been "hogged" by the groups in the
Northwest.  This has led to promotion of certain crosses over others that
might work well elsewhere.  Anton pointed out that OH x F 51 has been ideal
for his area, and it is also is excellent for Houston (zone 9) producing a
40-50% sized tree with large fruit.  It has the bad rap of not fruiting
well, but this is likely a Northwest phenomenon.  The differences in the
performance of the OH x F crosses are most apparent in the South, presumably
because of the chill differences.  Here, in addition to 51, 40 is reasonable
but significantly larger than 51. 87 seems about the same size as 40 but is
more precocious, but also does not have the root anchor the first two have.
97 does not work well.  333 is dwarfed nicely, about the same size as 51,
but fruits poorly and has smaller fruits.  513 and 217 are bonzai trees.
Pyrodwarf, also an Old Home cross, but with higher chill than most, is even
less than a bonzi tree here, growing about 1-2 inches each year.  40 and
especially 513, seem to make good dwarfing interstems on calleryana.
Pyrodwarf, however, is not dwarfing in the interstem position.

     In colder climates, the differences in these rootstocks must be much
less apparent.  I recall Ed Fackler commenting that after 10 years, it was
difficult to tell these apart from each other.  Pyrodwarf might well be a
good performer in the very cold areas, going back to the original query.

                                    Regards, Ethan