Did Saruman kill Radagast?

[Valandil]

Crazy, after all this to-do, but I'm having second thoughts.

It might not have been so imperative for Saruman to kill Radagast after all. After all - with Gandalf's escape, his cover was blown. Saruman would now be known for who he was.

Maybe he WOULD make an attempt to lure him back to Isengard (and this DOES make sense as the best way for Saruman to go about taking him out - neither going to Rhosgobel himself or sending an agent (crossing the Anduin into that territory could have placed him at risk) or trying to get Sauron to do the job. And if he made some sort of attempt to lure him back - Radagast might well have left Rhosgobel. Then again - if he was successful in the attempt - Radagast may have gone to Isengard anyway.

What else accounts for Radagast's absence though? Did he, upon learning of Saruman's betrayal (possibly soon - from Gwaihir), spread the word to the creatures he cared so much about, especially any who might be likely to suffer in the days to come?

It IS curious that he doesn't seem to have much connection with the Ents. Or else, maybe he does, but Treebeard sees no reason to mention him in the same breath as Saruman and Gandalf. He WAS a different kind of Wizard. Might he seem to Treebeard as not even a Wizard at all? And Treebeard was not one to spill all his thoughts when speaking anyway.