Root grafting coast live oak

Hi All,
wondering if anyone has any experience root grafting on coast live oak. If so here are some questions:

  1. Is there a specific oak species/varietal that would be better for root grafts?
  2. What are some things that I should look for to tell me the tree is ready to receive root grafts?
  3. Would I be better off air layering the burl off of the existing root structure?
    I’ll post a pic shortly

These are pics from earlier this year when it was collected. My intention is to perform this work sometime in 2019.
You can see two knobs sticking off the side where two large roots were cut at the time of collection. I cut the bark and cambium back and packed the area with moss thinking that if I’m lucky some new roots will form at these locations. That was in April of this year. The tree has responded well and has been putting out several new shoots.

Hi @ryan.marin,
I have no experience with coast live oak, but with it being deciduous, I would favour an air layer next spring. It will give you a good nebari without the weakness of a graft. Love the character of that trunk.

If I air layer will I need a branch below the air layer?

Hi @ryan.marin,
If you were air laying a conifer, then yes, but you should be good with deciduous.
I would wait until it’s energy positive, then ring bark it where you want the new base to be then earth it up. If the new roots have gaps, then think about root grafting between them. You could try taking cuttings for root grafts?

Well, this is a broadleaf evergreen (quercus agrifolia).