First time trying persimonn grafting last year. Epic fail.
I am amazed at the growth. You can see the failed graft on right and the new growth that started on left.
My question is can I cut it off below the Y (fork) and try again?
View attachment 33875
Here is what I would do and why, but I'm making some assumptions so let me know if they are wrong:
1) Below the V is 3" - 4" diameter or more.
2) You tried to graft one side of the V and left the other original.
3) You use a bark graft since you mentioned having the sap running.
So, here are my thoughts as to why the graft failed and how to proceed:
A persimmon wants to push natural growth before pushing a graft. Leaving one side of the V natural gave the tree a place to put the energy. It is a bit hard to tell from the picture, but it looks to me like a single water sprout formed immediately below the graft and replaced the right side of the V by growing around the graft and the damaged area of the graft died. Bark grafting too early before the sap is running could be another cause for failure.
If my assumptions are correct, I would cut off the right side of the V just below the bottom of the new growth now and seal it with laytex paint or a grafting sealant. Wait until you have leaves at least the size of squirrel ears (bigger won't hurt), then bark graft again. I would cut the lateral branch growing to the left of the V off and cut the left side of the V at about the same height as you did the right last year. The reason I would not cut below the V is the size of the wound is pretty large. I've found more failures when bark grafting trees over 3" than in the 1"-3" class. I think this is largely due to the size of the wound when cutting the tree down. A scion my even take and grow, but disease or insect damage to that wound seems to happen over time. I have not seen this with smaller wounds. That is not to say that I have not seen some success in grafting trees over 3". I would also bark graft at least 2 scions. Just put them on opposite sides of the trunk. I like to wrap my scions in parafilm-M. It thins as it stretches. It helps keeping the scion from drying out while it is waiting to take. Buds can easily push through the parafilm. I like to cut the top of the scion off at an angle above a good bud (like in pruning) placed to the outside of the tree. I don't leave terminal buds on the scion and I don't want more than a couple buds on the scion. As Native says, pencil size is a good diameter to target, but I've had success with scions a bit smaller and a bit larger as well. Last year's growth makes good scions.
With many grafting techniques, cambium alignment is key but bark grafting is different. With bark grafting good pressure is important to keep the bark peel held tightly against the back of the scion. I also like to make a slight angled cut on the back side of the scion (away from the tree) in addition to the normal angled cut on the front. The one on the back is small near the bottom. The reason is simply to expose a little bit of scion cambium to the inside of the bark peel. Electrical tape stretches a bit and works well for bark grafting persimmons. Make sure you don't touch the inside of the bark peel or the inserted portion of the scion with your hands prior to insertion. Below the graft, tape a bamboo stick or fiberglass rod as a stake to the trunk and point it upward, the way you want the scion to grow. It should be a couple feet taller than the scion. Birds will land on it instead of the scion. Movement of the scion once grafted can be a problem.
The next step is more important than most folks think. Each week after grafting, go check the tree. Remove any water sprouts coming from the trunk below the graft. The tree will favor these over the graft if they are not removed every week or two. By removing them it focuses the energy into the scion. As the scion grows , very loosely tie it to the stake. They grow so fast they can't support themselves when green. You want the scion to move some in the wind but grow upright in general. Once it hardens off the first winter you can remove the stake. At that time you should select your best one if both scions took. It is ok to let them both grow during that first year as there is more energy from the established root system than they can use, but remove one of them. If you leave them both you are creating a bad crotch angle that will eventually become a problem.
Hope this helps,
Jack