I picked up another load of juice this morning and asked the guy who runs the press about their policy on using windfalls. He said that they dont use *any* apples that have fallen on the ground, not even if they have just been on the ground for a short while. He said that he not only *wouldnt* use ground apples, because of risk of contamination, but that every year he has to certify to the health department that he *doesnt* use already fallen apples - for the same reason
Showalters orchard has great juice. Its the only juice, other than stuff I've pressed myself, that I've been able to ferment to dryness using just the natural yeast, without getting weird flavors. If they dont use apples that have touched the ground, I would advise you to do the same.
Perhaps the practice of adding k-meta before the yeast practice got started because of sloppy orchard practices - like using ground apples. But these guys run a really tight operation and I have never had a problem skipping the k-meta when I use their juice.