Blenheims are famous for canker around here, and I wouldn't plant nor graft any Blenheims. So you could have a reservoir of canker on the stock. But I am not sure if it would be the same in your case. Over here, the Blenheims rarely every bear crops.

All pluots that I have experimented on are vigorous on apricots, much more so with Apriums that they seem to take over the apricot that you gaft them to.

Japanese plums (aka Asian) will also be just right on Apricots (not too vigorous as pluots or apriums would be). Actually the Asian plums were called Japanese plums, and the Japanese plums did not really originate from Japan but from China. As credit to the Japanese, they were the ones who worked hard to improve most of the plums that originally came from China, so the world has known them to be Japanese plums. Now to prevent confusion between origins from China or Japan, we simply call them Asian plums.

The European plums, excepting for very few types, are usually poor growers or incompatible on my apricots.

I will be experimenting with Nanking Cherry if I can do a lot of prunus cultivar grafts on it. I love its small stature.

If you really want many species grafted successfully together on one tree, I would rely on using apriums as the stock or interstem. These interstems first grows upright after grafting and so easy to position and receive various grafts on a tree without them crossing over, minimizing competition and agressive pruning to keep the grafted cultivars balanced.

Joe,

As always, thanks for your thoughts.

The seedlings do not appear to have any disease problems. They are all too vigorous -- I've chopped most of them to the ground before, and they send up large new shoots with great rapidity. I have only been able to eliminate them by digging them up or "nuking" them with Roundup.

Most of them are coming up in an area that I have been trying to grow tomatoes in. The tomatoes have done extemely poorly in this spot for the last several years, however. Therefore, I am thinking of giving up on tomatoes (in this area), and trying to work with nature (i.e., the volunteer seedlings) rather than against it.

I was not thinking of doing multi-grafting with these plants (at least not yet). It just seemed like it might be a good idea to graft a few of them over to some good apricots and/or Asian plums (or plumcots).

I would graft Harcot over them. These are good tasting, and you surely have enough chills for these moderate chilling hours apricot. They can produce even when disease abound. Partially self fertile, but expect about 3 to 4 years to fruit if you graft over the seedlings. Then you can graft Flavorella, Apriums, most other apricots unto Harcot. I would graft many apriums as later, you can graft plums, pluots and the whole prunus over them.

I believe plums are generally compatible with Apricots. If the growth is really seedling growth coming from below the graft union, the variety of tree (Blenheim) is irrelevant. What you are grafting is whatever rootstock the tree was grafted onto. Many apricots are actually grafted onto peach rootstocks. If the suckers are coming up from around ground level and you want to put them to good use, cover them with potting soil and water the soil. The suckers will root and the following winter you can remove them and you will have numerous seedlings to graft to. I did it several years ago and now have several peach trees which I didn't have to pay for.

Joe,

Thanks for the additional suggestions!

Rgranel,

These are definitely actual seedlings from pits that have fallen to the ground, not suckers from the mother tree's rootstock. They are all quite well-rooted.

Here's a chart that I found that contains quite complete information.

Here is a link that might be useful: Link

Lonnie,

Personally, I would not use a seedling from the actual fruit as rootstock. There are reasons why trees are grafted on certain rootstocks. The quality of the fruit that you will get and the overall performance of the tree is uncertain. But if you have space and time, I guess you can experiment.

that would only be true for non-nucellar types of seeds. Many good cultivars came from chance seedlings, chance pollinations, having been observed by the very keen eyes of backyard gardeners.

hobbyists thrive on uncertainty and experimentations, for us these are one of the many exciting things in life. It is not our main bread and butter.

Commercial growers loathe uncertainty and would have miserable life if it looms over their heads. I would too, if my financial life is on the line.

Rgranel,

I'm aware of the benefits of clonally-propagated, standardized rootstocks.

It's just that in this case I have some very strongly-growing seedlings in spots right where I could use them -- and it just occurred to me, "Hey, why not give them a try."

Some of them have pushed growth so rapidly that I think that I could ascertain graft-performance pretty quickly. (As I said, long-term decline is my big concern.)

There are all kinds of clonal rootstocks for the common deciduous fruiting crops, but not for many minor subtropicals. I've used seedlings extensively for grafting things like loquats, capulin cherries, and white sapotes, because there are no standardized rootstocks for these species. So now when I see any strongly-growing seedling, my mind naturally turns to the idea of grafting.

(By the way, it would never occur to me to actually grow out those apricot seedlings themselves in the hopes of getting fruit -- I certainly don't have the space for that kind of experimentation!)