That’s a great point—thanks for bringing it up! So far, I’ve been using Daiougoumi as an isolated mother plant. This cultivar is not self-fertile.
In my collection, the cultivars I can confidently confirm as self-fertile are Sweet Scarlet, Gutsulska, and Cheriffic. We can definitely build a more complete list—please feel free to add any cultivars you know for certain are self-fertile.
I got an email reply from Sylvatica Forest Farm regarding their Select Goumi scion wood.
“I did follow up on this but it lead to a dead end! All I know is they are super heavy producers of light red, jello/rhubarb textured berries about large olive sized. If you want, I can send you photos when they fruit in a month of so!”