North American Fruit Explorers mailing list at ibiblio

[Patsy King <pking888@gmail.com>]

I know nothing about pawpaws but wondered about graft incompatibility.  A
google search brought up this response to somebody whose trees die in the
fall:  (I put bold formatting on the pertinent part):
Several possibilities come to mind for the cause of your trees death.
Pawpaws require a well drained soil and we have had two wet seasons back to
back. Saturated soils make trees much more susceptible to Phytophthora root
rot. If the roots are dead this is probably the cause. This particular tree
may have been growing in an area where water pockets after a rain or in a
drainage area. *If the tree is a grafted one and the roots are alive (You
can cut through the bark with a knife and see green tissue), but the top of
the tree is dead the problem could be graft incompatibility with the
seedling rootstock. This can show up a number of years after planting.*
There is not much that can be done about this other than plant another
tree. Alternatively if you look very closely at the dead top of the tree
and see a multitude of pin head sized holes with what looks like a
toothpick sized extension from the hole of sawdust the problem is Ambrosia
beetle. This insect attacks trees that are growing less rapidly or are
stressed. A targeted spray program for this insect is needed if this is the
problem.

The URL of the info above is:
https://ask.extension.org/questions/293442

<https://ask.extension.org/questions/293442>
I found more fascinating info here, mentioning that pawpaws usually are not
grafted, and why.  But it does tell how the writer did the grafting when he
tried.
http://rarefruitclub.org.au/Level2/GraftingPawpaws.htm

Were your grafted trees all purchased ones?   I was not able yet to find
out in some quick googling, what rootstocks/scions to use in order to avoid
graft incompatibility.