Advice for an old crabapple air layer?

[amanwithaplan_t]

I'm new to bonsai, just removed an air layer from a crabapple and wondering if this is likely to backbud on the old wood? Some pretty thick craggy old bark, unfortunately it's position on the tree was far, far away from any new growth or younger branches. Any advice or suggestions on how to encourage it? I've watched videos about placing newly collected old Hawthorn trees in dark plastic bags to get them a leg up in the early spring, for example.

It took two full seasons to get enough roots to be removed from the parent tree, just for scale, the branch cross section where I cut is about 4 inches in diameter.

Just to hedge my bets I top-grafted 3 scions to it but have no idea whether grafts will even take on an air layer.

Any and all advice appreciated!

 

[Shibui]

Assuming your technique is good, your grafts have every chance to be successful. We can graft onto stumps of trees with no leaves and your apple is really just a stump with no leaves yet.

Apples are very good at new shoots on bare wood. I'd be 99% sure of buds on this. Some apples are prone to suckers from the roots so I hope yours doesn't put all its effort at regrowth into suckers and not the old trunk.
As far as I'm aware, bagging, etc is to help trees cope while they have very few roots immediately after collection. Bagging does not promote buds, it just keeps them alive while the new roots get started. I assuming you already have roots and, typically, layers have plenty of new feeder roots where collected trees have thick roots but few or no feeder roots.
I don't think bagging will help and can actually promote fungal problems.
The only thing I can suggest is watch soil moisture. Without leaves your tree can't draw up much water so the soil usually stays wetter than other trees. It will probably require less water until new shoots develop.

 

[amanwithaplan_t]

Thank you for your response! I agree that the plastic bag method is not a good plan for this for the reasons you mentioned. Nice to hear that apples backbud easily from old wood. My grafting technique is not exactly tried tested and true, but I did seal everything and get nice clean sterile cuts so fingers crossed. I'll watch the soil moisture as you advised, I suppose this would have been more ideal in a more aerated blend like pumice/akadama? I'll watch for suckers and try to pinch them off if they start at the callus area.