Del,
Thanks for your rundown on the first and last plants to begin growth
this year. I always like to compare notes.
As for Jap/Am plums grafted on P. americana, I have some 4 year old
grafts at about 3 feet that haven't shown any problems yet. Probably
too early to tell. It might depend on the what varieties, what
variety was your source referring to?
Kevin B.