Early this spring, I decided to top work a fairly large tree with the idea of creating a tree just to grow Pawnee scionwood. This particular tree had two main stems, each about 2.5 inches in diameter. I used my chainsaw to cut the top out of the tree and then placed two bark grafts on each of the cut stems (photo at right). In normal circumstances, I top work a tree by placing just one graft on the central leader. However, because my goal was to produce scionwood, I choose to make multiple grafts to increase the number of new shoots produced.
Three weeks after grafting, the buds on the scions started to show signs of life. To my surprise, bud break varied widely among the 4 scions. Now this was interesting. I had grafted 4 Pawnee scions onto the same tree using the exactly same grafting method but I achieved different results.
The photo at left shows a pair of bark grafts growing from one of the main stems. Note that the graft on the left is more advanced than its companion on the right. Why the difference? I have no easy explanation.
Moving over to the other set of grafts (photo at right) you will note that one graft is starting to form new shoots while the other has only swollen buds. Again, why?
For the time being, I'm going to just sit back and watch these 4 grafts as the season progresses. When I unwrap the grafts later this summer, I might spot an explanation for these differences in performance. However, sometimes the mystery of grafting success (or failure) forever goes unsolved.
