I have used a teaspoon of 80% Mancozeb in a gallon of water to soak
apple sseeds overnite. However, the biggest problem is damping off of
the seedlings when they are 3-4 inches tall. I prevent that very
successfully by adding a little Benlate 50% (one half teaspoon to a
gallon) to their water every time untill seedlings are 8-10 inches, make
sure the water is PH adjusted to 5.0 byadding a little vinegar. Make
new water each time, don't try to save. Also don't bother with ANY
seeds from a moldy core apple.