I think I'm done bud grafting columnar trees so I'll stop and take stock of my progress at the end of my 2nd season of grafting.
Two years ago, I bought 7 grafted trees to establish in my backyard and got some scionwood for bench graft. My bench grafts yielded 2 trees and I got 1 more by field grafting what I snipped off the grafted trees. I planted a bunch of P18 and some B118 to bud that summer using what wood I could get off the 7 grafted trees. With the short growing season, some of that budwood might have been immature and I may have removed my pvc tape too early from some. Others I pruned off too close to the bud after growing started and killed the whole tree. I'm not sure how many I budded last year but but I got 9 trees and none in what will be my first shot plot. I collected some scionwood last winter and bench grafted about 18 and only got 5 takes. I know part of my problem using 1/2" caliper rootstock that better matches the thick columnar scions but produced a big cleft wound to heal. I also bought 3 more grafted columnar trees of varieties I did not have.
After all that work and grafting, I have 16 columnar trees that I grafted and 10 that I purchased. While I have learned a lot, I am a little disappointed that I am not farther along. I kind of feel like I lost a year.
On the good side, I now have lots of budwood and scionwood to continue propagating. I have now budded 49 trees in the last couple weeks and I might bud a few good bench grafts in the nursery that I don't need. I am hopeful using buddy tape will increase my success rate and I won't prune the rootstock off so late next year. I can dig up and move my good grafts next spring and set up another shotplot. I have over 25 seedlings I am growing in my backyard to see if they will be columnar. The columnar trees I bought have 7 or 8 apples that I will collect seeds from and start next year...need to decide where those get planted for evaluation.
And I just found out that a scab resistant columnar crab Rosalie will be available next year for sale that should be a great apple for my shotplot. It has 2" apples, ripens in mid October and is said to hang well into November. I will have to find couple even though I think they will be pretty expensive, probably sold as $75 potted ornamental flowering crabs.
I am reconsidering some of my other ideas that are likely to be more of a distraction. For comparison, I wanted to try doing shotplots with dwarf rootstock (G.11 and G41) and interstem trees. I have enough good dwarf trees now to do one but I'll have to decide where and get the site prepped. For the interstems, I got scions from GRIN and elsewhere and bench grafted onto MM111 and B118. For interstems, I used super dwarf (M27, G65, P22 and B146) and dwarf (G11, G41, P2, Ottowa 3). I decided not continue with the larger dwarf interstems and I budded those to columnar trees. None of the super dwarf are far enough along to bud to the interstem or collect budwood. I guess I'll let them stay in my nursery for now and decide later whether and how to proceed. It would be quite a few years to get an interstem shot plot to evaluate. I'd have to do the interstem bud in 2017, bud a deer apple variety onto the interstem in 2018, move to a shotplot in 2019, probably get apples by 2021. Maybe I'll just move them to the farm next spring, cage them, and see what they do.