How to determine species of rootstock
I have a few plum and peach trees purchased in Lowes and home depot 6 years ago. The Plums are "Santa Rosa" and "Burbank". The peaches are "Hale Haven" and "Elberta". They are semi-dwarf. Is there any way to determine what Rootstock they are grafted on? Specifically, I would like to know if the rootstocks are peach or plum. the specific variety is not important.