Speak to Furgus Warpwood.
Just inside the eastern wing of Dire Maul one of the warpwood ancients, Furgus Warpwood, still lives uncorrupted. You must travel there and help him drive out the terrible creatures that have taken it as their own. Taking Dire Maul would be a major step in reclaiming Feralas for our people.
You can find Dire Maul to the southeast of here.