Here's an update on the Dolgo seedling rootstock I purchased from Blue Hill this year.
I bench grafted 70 of them in mid-March, by cleft grafting them. By around mid-April, some of the rootstock had new growth a couple inches long, and since they weren't getting any light and the leaves were very yellow, I moved them all outside. We had a couple of 27 degree nights after that, but it did not seem to phase the growth on the rootstock.
Out of the 70 I grafted, there is just one where the rootstock and scion never woke up. One other rootstock has something wrong with it. The leaves on that rootstock and scion are reminiscent of what a glyphosate damaged tree's leaves look like. I'm not saying it is glyphosate damage, that's just what it looks like. It could be genetics. The scions on two others died after initially displaying swelling buds, but the rootstock is doing well, so I can bud them in August. Overall, 94% of my grafts are looking good right now.
None of the rootstock have red leaves.