Yes, that's correct, my original frankentree has about 140 varieties on it. The virus has not proved to be much of a problem, just affects the leaves of some varieties and none severely so far. I also have multiple apple trees with many different varieties on them and am always adding and removing. I have thought about doing some
art with grafting, like bark textures for instance. There can be issues for sure. One is suckering which can be exacerbated by interstems for instance. There can also be issues with vigor. Vigorous varieties like Katherine Etter (awesome apple) tend to overgrow, while weak some very weak ones will get crowded out. An issue with the tree of thing pictured on this
thread would be getting varieties that all flower concurrently. In general though, I've had very few problems with multigrafted trees and lots of benefits. I'm so stoked about the idea that I did a follow up article encouraging people to dive in and go for it and would pretty much like to start a movement. The benefits are many and I think most small scale homeowners and homesteaders, would be better served by either multiple restricted form trees, or larger multigrafted trees. Pollination is better, you get more variety, longer season and it's just neat. I don't know much about nursery trees that are multigrafted, presumably by budding, but I've had great success with frameworking trees once they are established a little. Once a person knows how to graft, a lot of things can be fixed if they don't work out. Most of my experience is with apples, but I have a frankenplum and a frankenpeach that I'm slowly working on.
Grafting as art. There are so many things I would like to try to do in this realm. I think people are way too conservative in grafting. We are afraid the grafts won't take, so we follow whatever we are told or what has worked before. I've done a heart shaped tree in which the sap flow had to reverse at the top of the heart before going into the scion. It's doing very well in it's probably 4th year? I also did one tree where I stacked 6 consecutive grafts one on top of the other, staked it firmly and bound it to a bamboo to keep it stable. Every graft took. Each stick was a different variety, my attempt to make a tree that was a different variety for each scaffold branch, grafted in one year. But, some failed to thrive, while others grew out vigorously. I concluded that the varieties would probably have to selected carefully for equal vigor and never grew that tree out to see what would happen. I mostly wanted to see if I could get that many grafts to take. I've also made very long grafts, at least 3 feet long. Last year, I grafted about I think it was 70ish seedling apples onto dwarfing stock as part of my red fleshed apple breeding
project. I left all of the scions full length, some up to 2 feet long, with 100% take. I'm not bragging (okay, not much:) my point is that I think we can really push the boundaries more than we might think, and we
should start testing the limits
For long scions, paint the entire scion with a sealant. I usually use Doc Farwell's grafting wax.
Stabilize grafts, tight wrappings and support as needed. If long or prone to movement for any reason, binding to a form or stake can really help. Think of it like splinting a broken bone.
Be able to sharpen a knife and keep it sharp
Flat, well fitting cuts wherever possible, with maximal cambium contact.
Disbud at least some of the buds you don't need to direct
energy where you want it, but leave enough for the tree to photosynthesize adequately.
With those ideas, I think we can go far in terms of grafting forms. As far as a tree like that picture, that would be really easy, except for varietal selection. I would grow basically a crap ton of plums in a row and watch them closely for years before deciding which to use for matched vigor and blooming dates. Length of bloom time and density would probably also be important. A big investment, but seriously cool! It would probably require maintenance, but so what.
And a frankentree in every garage! https://turkeysong.wordpress.com/2014/01/29/and-a-frankentree-in-every-garage/
The path to knowledge is paved with blasphemies