Chullin 77: The Placenta, Medicinal Practices

We are introduced to a new Mishna that discusses whether or not a placenta is permitted to be eaten.  We learn that it may be eaten though it is not considered to be an ordinary food, and that it may be buried but not at an intersection nor hung on a tree.  This is to differentiate our practices from those of the Amorites.

From www.newSteinsaltz.com, we learn: 

     'The ways of the Amorite” refers to activities that are not truly     in the category of idol worship, but they are non-Jewish traditions that are forbidden based on the passage in Sefer Shemot (23:24, and see Rashi there) “…nor do after their doings.” Another source for this prohibition is Vayikra (18:3) “…neither shall you walk in their statutes.” In particular, these are understood as referring to practices of magic and witchcraft."'

Abaye and Rava agree that medicinal practices are permitted, but non-medicinal practices are forbidden as Amorite practices.  This means that the practice of painting a tree with red paint when its fruits fall off and then putting stones on the tree is permitted.  Why?  Because the stones limit the tree's strength and the paint draws people's attention so that they might pray for the tree.  Not what we might call medicinal, but certainly a practice toward helping trees - perhaps if the fruit or the tree were used medicinally, this would be a more logical practice.