Sorry, I haven't looked at this site for a while. Good scion wood for whip-and-tounge grafting is obtained from the current years growth.
Usually between 3/8" and 1/2" in diameter. You collect the scion wood, (at least with deciduous plants), when the plant is dormant. With mayhaws, that would be during the winter...I'd collect the wood during early February.
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dstnflounder@embarqmail.com

Thanks...