My solution is to make a leaves_with_apple node that decays like leaves and drops a normal, non-decaying edible apple when dug. The problem with making unpicked apples nodes is that the apple texture can be shown up to 3 times for one node, depending on your angle. Several different possibilities:
Apple texture over leaves texture:

Leaves texture over apple texture:

Or, just make the leaves_with_apple look like a normal plantlike apple.
