I just ate a Gerardi Mulberry that was quite possibly the tastiest mulberry I’ve ever eaten. I am wondering now if it can be air layered. The mother tree is grafted so I know it is possible to do that. But grafting season is possibly over and air layering is easy to do now.
Air layering should work . You could also bud graft this time of year .
Bud grafting is an excellent idea and I have the right rootstock for it too!