Rufus knows Orga is out there, and Orga knows Rufus is coming. It's simply a matter of who's pride comes crumbling first in the middle of open waters where no witnesses can tell the tale except for them.
When Rufus first hears about the rot, it sends a panic into him. He has a good guess as to why the forest is dying, and he realizes he's been neglectful. So, with picnic basket in hand, he does the one thing he can do.
He heads toward the rot.