Originally Posted by
Diggie's Friend
There is a reason why not all acorns develop toxic mold. Since both red and black acorns do not germinate quickly, but remain in the soil uncompromised for months if not cracked or accessed by nut weevils, that drill into the capsule shell of the acorn while it is still soft to deposit their eggs in it, the larva will drill their way out that opens up the acorn to fungus. For this reason, sealed red and black acorns remain in tact without fungus though the winter; so if they are not consumed after a few months they will they eventually dry up..
White acorns, on the other hand, are most often consumed on the spot by tree squirrels, rather than buried; for these acorns germinate quickly. Save that a squirrel bites off the embryo end of the nut capsule, which moreover prevents the kernel from germinating, this will extend the viability of white acorns shorterm.
(For reference: see North American Tree Squirrels by Michael Steele and John Koprowski)