Repotting Apple Seedlings. 6.21.2021

I noticed that the Calypso x Golden Sentinel apple seedlings, that I started during the winter, seem to have started a growth spurt. I transplanted them into larger containers. I've never grown apple seeds, so this is new to me. The stems seem stout, with narrow internodes, so maybe they are columnar like Golden Sentinel. I don't know for certain. One had mildew during wet season and they look a bit fuzzy now? So I sprayed them with "Safer" sulfur spray.