The leaves and berries can be cut from the plant safely, but when the mandrake root is dug up, it screams, potentially killing all who hear it (make saving throw against death).
Harvesting the RootThe proscribed method is to befriend a dog, which one should encourage to be loyal and obedient. A furrow is dug around the root of the mandrake plant, then the dog is tied to the plant's base above the ground. After which, the harvester should move to a safe distance (30 feet) and call the dog. At this point, if the dog succeeds in making a morale check, it will rush towards the master, pulling free the root and being forced to make the save against death itself. At that point, the mandrake root can be handled safely.
However, if the dog fails its check, it will fail to come, sensing the danger and remaining where it is. In this instance, the dog will remain where it is until it starves to death or is freed, whereupon thereafter it will prove useless for the harvester's purpose (it will never move away from a mandrake root to which it is tied).