Myself, I tend to let mother nature have her way. Fungicides are tricky with seeds and seedlings, and in general more toxic to humans and animals than insecticides. You would also need to research which fungicide(s) would work on molds (assuming that is what you had). Just like all insecticides don't kill all insects, all fungicides don't work on all fungal organisms, either. Are molds oomycetes? If they are, you could try cinnamon as a moldicide.
