North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

Steven, to make a list about shade tolerance of prunus one needs to define
what shade tolerance means.  What's important will vary in different sites-
especially from region to region but also micro-climate to micro-climate.

I assume your list is based on levels of shade in which a tree can still
produce satisfactory yields of sweet fruit.  Where I live, black knot can
be such a destructive pest that it trumps all other issues.    For example,
I had a Methely plum on my property that only got about 5 hours of direct
sun in mid-summer- probably 2/3rds shade.  For about 4 years it was an
excellent producer of good fruit but the black knot got worse and worse no
matter my diligence.  I finally cut it down as it was a real Typhoid Mary
to the plum trees in my nursery and cutting out the BK was taking too much
time anyway.

Near the same spot I had an Elephant Heart that actually bore much larger
crops and without the rampant pitch pockets than the tree I have now in
full sun.  (I suspect that the one in full sun is excessively vegetative
because of access to laundry water).

Cherries perform terribly here in sites with eastern shade because you need
to get the dew off first thing in the morning or they tend to crack, even
without rain.   Otherwise it would do well.

I feel most cherries and plums can produce fruit with good sugar in similar
levels of shade but peaches need more light.  This would coincide with the
relative brix levels to begin with.  High brix prunus can take shade and
still be sweet enough- low brix needs more sun.  All prunus seem capable of
producing decent crop loads in shady areas IME.

A second consideration is the exposure level at time of ripening.  Sites
often will get much more sun in July than September so early ripening fruit
may have an advantage.