I was afraid that this would happen, but of the 72 apple seeds I planted, only two sprouted. The rest turned into big balls of mold in their trays. One of the seedlings wasn't able to break out of its seed completely, so that leaves only one healthy apple sprout. Well, it's a start. I'll collect more seeds this fall and try again. I think I'll also keep track of their sources, since I have no idea which seed produced this sprout.