Wiktionary says of Erdapfel (which OP admittedly with '?' wasn't sure how to translate): > From Middle High German ertapfel, erdapfel, ertöpfel, erdöpfel, erta

Wiktionary says of Erdapfel (which OP admittedly with '?' wasn't sure how to translate): > From Middle High German ertapfel, erdapfel, ertöpfel, erdöpfel, ertaphel (“mandrake, cucumber, pumpkin, melon”), from Old High German erdapful, erdaphul (“pumpkin, squash, melon”)