[Olm]

No, I have no crones there, only mothers. The old ladies did not join battle yet. And a couple of those mothers are diseased, as well as Lord wardens Castelans and Bards. Normal troops are affected too (only the Knights of Avalon seem to be Immune (or its unlikely on them due to the recuperation) I suspected a Bone Venom Charm, but even with heaviest patrolling I could find none.
Probably some disease spreading Site.

About aging: I don't see that much problem with it. I have growth 3, and I just live with it. Until now not one crone has died (but I recruited them late, I have to say) I have two or three now, that are diseased.
One way to work against age is buff their Nature. For a N4 Crone one
Thistle Mace is usually enough to make them young. For N3 I'd need Treelord Staff or Moonvine Bracelet+Thistle Mace. But thats a bit to costly for my liking. (Though viable for very rare and useful combinations like A4, E2 or W2)