This quest is no longer available within the game.
A Cenarion beacon will allow a well-trained skinner to spot patches of tainted skin from bounty gathered in Felwood. I convert these seemingly useless patches into a thick paste that serves as a quickening agent for Cenarion plant salve. When you skin your kills here in Felwood, be sure to have a beacon on you!
When you collect tainted patches, bring them to me and I will give you some Cenarion plant salves that I have already made.