Greg; I hope I've got this right..? You're planning on removing the upper portion of a single-variety Gravenstein tree at a trunk diameter of 3.5 to 4 inches; then you'll place back on some of the same Gravenstein wood?
If the top portion of your Grav. is too vigorous, or dominant, can you live without those lower branches..? Either one or the other will become dominant; if you remove that center section, wouldn't you rather have the energy go into beefing up those lower limbs? If you successfully placed 'more Gravenstein' above them, would you not fear it over-growing again?
My trees are all "open vase" pruned, if you're going for a "central leader," you may have it ... just prune that central section to allow enough sunlight to reach the lower limbs, but leaving a "top," with associated fruiting potential.
If you insist on making this graft, that's definitely pushing the limits size wise... I'd defiantly do a 4-way cleft graft -- with some â€œInverted Lâ€ bark-grafts a few weeks later, and lower. But there's still going to be a lot of surface area to heal over, and it never seems to heal tight enough to avoid rot down the center... Wish you could have made it to our classes; a description was given of this same 4-way graft - where the eventual (4) shoots are twisted tightly together where theyâ€™ll naturaly graft
, forming a 'single limb.' There's a little more to it than that, but it sounded like fun
As the class seemed to debate the ultimate size of cleft grafting stock, I suggested that larger stock could be cut out, and if left alone, would send up beautiful candidates for whip & tongue grafting next spring... Letting nature do it for you! And, if you only want to retrain your 'leader' you'd have all the shoots you'd need to play with. Heck, graft something different onto each one!
That said ... I hadnâ€™t forgotten your request regarding the "Old Gravenstein" apple tree I secured wood from:
I'd be interested but I can't get to the scion exchange. Gravenstein's are great apples
Can you believe I forgot to bring any of that wood to those classes
? Though nobody asked... but I do plan to have it at the Scion Exchange
(or I'll go home after it!). Anyway, I was going to suggest you send a private message to our Web Master, Steven, and give me your e-mail / mailing address so I might send you some of this wood..? But maybe now you won't need it?
: if you insist in removing that central trunk, make a level cut 8 inches above the highest of those lateral limbs. I wouldnâ€™t even seal the cut â€“ just let it send up shoots from the latent buds inside its bark. As each gets 6 to 8 inches high, pinch out the tips
on all but
those youâ€™d like to train or graft to. Leave the rest alone! Next year, about this time, you can decide what, if anything youâ€™d like different on that tree? Or, twist them all into a tight bundle, tie, and aim the tops into new branch positions â€“ Art!